NAS-NS-3063.txt

 

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NUCLESR SUIERCE SERIES
Radinchemistry of the Elements

 

R\%

TAE RADIOCHEKISIRY OF URANIUH, REPTURIU ARD ?EUTO&IUH - AN UPDATIRG

NAS-NS--3063

 DE86 007600
by

. Richard A. Roberts
Hallinckrodt Medical Products R & D
- 8§75 HeDomnell Boulevard
St. Louis, MD 63134

Gregory R. Choppin
Department of Chemistry
Florida State University

Tallahessee, Florids

and

John F. Wiid
_ Nuclear Chemistry Division
Lavrence Livermore Reticnal Lsboratory
Livermore, California

Prepared for Committee on Ruclear snd Radiochemistry
_ Board on Chemical Sciences and Technoleogy
Commission on Physical Sciences, Mathematics, and Resources
National Academy of Sciences--Rationsl Research Council

Februazry 18856

 

Published by

TECHRICAL INFORKATION CENTER
OFFICE OF SCIENTIFIC AED TRCHNICAL IRFORHATION
USITED STATES DEPARTMERT OF ENERCY
Fanflufl

"

‘\__

The Committee on Nuclear agnd Radiochemistry is one cf a aumber
of committees workimg under the Board cn Chemfical Sciemces and
Technelogy of the Commizsion on Physicel Sciences, Kathematics,
and Resources of the Hationzl Acadery cf Sciencesz--Kational
Rezearch Council. Its mezbers are drawn from scademic,
industrisl, and government laboratoriecs &and represent the areas
of nuclear chezistry, radiocheeisctry, end nuclear medicine.

The Committee hes concerned itself with theszs areas of
nuclear sciance which involve the chemist, such ag the
collectionm and digtribution of radiochemical procedures,
speciglized techniques and instrumentetion, the pleacse of nuclear
and radiochezmistry in college 2nd unmiversity programs, the
training of nuclear and radiochemists, radiochemistry in
environzmentel science, and redionuclideszs in nuclear medicine. A
major interest of the Committee is the publicaticn of the
#uclear Science Series of moncgraphe on Radicchemistry znd on
Radiocherical Technigues. In 1982 & third ssries on Ruclear
Hedicine ves inftiasted. :

The Committee hes endeavored tc present monographs that wiil
be o0f maxieum use to the working scientisgt. Each monograph
presents pertinent information required for razdiochemical work
vith an Individual element or with a2 specielized technique or
with the use of radionuclides in nuclear gedicire.

Experts on the varicus subjectsz haee been recruited to write
the monographs. The U.S. Department of Energy sponsors the
printing of the series.

The present monograph is & comprehensive revision and update
of three previously published monographs in the series on the
Radiochemistry of the Elements, It is published 23 part of our
continuing effort to update, revise, snd expand the previously
- published monographs to keep them current and relevant.

Edvard S. Hacias, Chairmen
Committee on Buclear and Radiochemistry

iid
Preface

This monograph presents some procedures used in the
radiochemical isolation, purification and/or analysis of vranium,
neptunium, and plutonium. The original monographs were:

' The Radiochemistry of Uranium, J. E. Gindler, NAS-PS-3050
{1%862), 350 pp.., 18 procedures.

The Radiochemistry of Neptunium, G. A. Burney and |
R. M. Barbour, NAS-NS-3060 (1974}, 229 pp.., 25 prpcedures.

The Radiochemistry of Flutonium, G. B. Coleman, NAS-NS-3058 .
(1965), 184 pp., 25 procedures. |

in addition to the description cf the procedures, these
earlier monographs list the isotopes and their nuclear properties
for each element. They also discuss the chemistry of the
separation processes of these elements with primary emphasis an
precipitation, ion exchange and solvent extraction technigues. 1In
this update of the procedures, we have nct attempted to discuss
the developmentes in the chemistry of U, Np and Pu but have
restricted the monograph tc the newer procedures, most of which
have resulted from the increased emphasis in environmental concern
vhich requires analysis of extremely small amounts of the actinide
element in quite complex matrices. The final section of this
monograph describes several schemes for isolation of actinides by
oxidation state.

" The individual procedures fram the earlier monographs are
ligted by title to provide a more complete view of available
separation techniques. The new procedures in this monograph are
included for each element following the list from the earlier
publications. L
R. A. Roberts
G. R. Choppin
J. F. Wilad

iv
 

Discussion of Procedures........ ... ........ccvcununn. e, 6
Procedures: |
1. Seri-Quantitative Determination of Uranium

( OSPeCEToSCOPY ) . -t ittt ittt it tecn e ennredannrannnnasannnsa 14
2. Concentration of Uranium by Coprecipitation

with Iron-Potassiuz Ferrocyanophosphonates..... ........... 16
3. Extraction of Uranium with TOA and Spectro;

photometric Determinatiorn with Arsenezo III............... 17
4. Determination of Uranium (and Plutonium)

Isotopes ir Soil Samplies by a-Spectroscopy................1l9
S. Anion Exchange Separstion of U in HMalenic

and Ascorbic Acld Hedla........... .. ...t ienennnn. 21
6. Sepsration of Uranium from Heavy Mecals by

Chromatograephy Using an Arsonic Acid Resin....... Ceeeean 23
7 Chromatographic Separation and C-Spectrometric

Determination of Uranduwa...................... ........... 26
8. Determinetion of Uranium in Natural ¥Waters

After Anion-Exchange Separation............ ............... 26
9. Uranium Analysis by Liquid Scintillation Counting......... 28
'10. Determination of Tracs Uranfum in Biologlcal

Matarials by FKeutron Activation Analysis and

Solvant Extraction...... ... ittt ittt iieanasinaea ..-31
11. Determinztior of Trace Ursniu=z by Instrumental

Reutron Activetior Anslysie........... .ot 33
.

VI.

ViI.

BEow Neptunium Procedyres. ... . ... oo iiiinremctrennncnnanaanaas 34
Introduction..,........... thremasraaaae e raraaeaer e 34
- Procedures: :

1. Chfonatographié Separation of Neptunium Using

Quaternary Ammonium Nitrate Extractant.................... 35
2. A Spectrophotometric Method for the Defernlnation

of Neptunium in Process Solut;ons ......................... 36
Eg!_zlg;gniyn_z;gggflu;gg ....................................... 38
Introdu;tion;........1............;....31 ........... AU 28
Discussion-pf the Procedures....... :.....:?.T .................. 38
Procedures:

1. Ligquid-Liquid Extraction Separatioh and

Detereination of Plutonium......... ... ...ttt nannnnn 40
2, Deterzination of Plutonium in Sediments by
Solvent Extraction............. D 42

3. Radiochemical Determination of Pluteonium in
4. The Determination of Plutonium in Environmental -
Samples by Extraction with Tricdodecylamine................ 46

5. Solvent Extraction Method for Determination
of Plutonium In Soft Tissue............ ...t encennn. 48

6. Determination of Plutonium in Tissue by

8. Extrective Photometric Determination of
Plutonium(IV) with Aliquat-336 and Xylenol Orange......... 54

3. Sizulteneous Determinations of Plutonium Alpha- and
Bata-Activity in Liquid Efflucnts and Enviromnmental

Samples......... e tasasiiessasssssascecesatecsnsnsanesaanns 55

 
15.

16.

17.

ib'

Roberzs/Choppin/®ild
page 1

- 1. Summary of Previous Urenium Procedures
. J. E. Gindler _
NAS-NS-3050 (1%62)

   

_Determination'of Uranium -237-

Purification of Uranium -2490

Purification of Irradiated Uranium -236

Uranium and Plutonium Analysis |

Spectrophotoretric Extraction Methods\Specifxc for Uranium
Determinaticon of Uranium in Uranium Concengrates

Carrier Free Determination of Uranium —237 

Radioassay of Uranium and Plutonium in Vegetation, Soil, and
Viater

Separation of Uranium by Sclvent Extraction with TOPO
Radiochemical Cetermination of Urénium'—237

Séparation éf Urahium and Bismuth
Isolation.and'Meésuremenfi'of Uranium at the Hicrogr&m Level
The Determination ¢of Uranium by Solvent Extraction

Uranium Radiochemical Procedure ngsed at the U.S. Raciation

- Laboratory at Livermore

Use of Ion Exchange Resins for the Determination of Uranium
in Ores and Solutions

The Use of a Compound Column of Alumina and Celluloée for the

~ Determination of Uranium in Minerals and Ore< Containing

Arsenic and Molybdenum

Determination of Uranium -235 in Mixtures of Naturally
Occurring Uranium Isotopes by Radiocactivation

Determination of Microgram and Submicrogram Quantities of
Uranium by Neutron Activation Analysis
10.
11.
12.
13.
14.
1s.

16.

17.

18.

Roberts/Choppia/iild
page 2

11. s&mnatl_gf Previous Neptunium Procedures

G. A. Burney and R, M. Harbour
NAS-NS-3060 (1974)

Separation of Np by TTA Extraction

Separation of Np by TTA Extraction

Determination of 23Np in Samples Containing U, Pu, and
Fission Products . '

e
Betermina;ion of Np "

Determination of Small Amounts of Np in fu Metal

Determination of Np in Samples Containing Fission Products,
J, and Other Actinides !

;etermination of Np in Samples of U and Fission Products
2xtraction Chromatographic Separation of 2°np from Fissicn
snd Activation Products in the Determination of Micro- and
Sub-Microgram Quantltzes of U

Separation of U, Np, Pu, and Am by Reversed Phase Partition
Chromatography

An Analytical Method for 237Np Using Anion Bxchange
Separation of U, Np, and Pu Using Anion Exchange
Separation pf Zr, Np, and Nb Using Anion Bxchangé
Separation of Np and Pu by Anion Exchange

Separation of Np and Pu bj Cation Exchange

Separation and Radiochzmical Determination of U and

Transuraniua Elements Using Barium Sulfate

The Low-Level Radiochemical Determinations of z”Np 1n
Envirommental Samples : .

Radiochenical Procedure for the Separation of Trace Amounts
2€ 237Np from Reactor Effluent Water

Determination of Np in Urine
18.

20..

21.

Roberts/ Choppinl!!i 12
page 3

Sunazary of Previous Neptunium Procedures, continued

Determination of 237Np by Gamma Ray Spectrometry

,Spectrophotémetric Determinafion of Nfi

Microvolumetric Complexometric Method for Np with EDTA
Photometric Determination of Np as‘the Peroxide Complex
Separation of Np for Spectrographic @nalysis of Impurities
Photometric Detgrmination of Np as tflg‘xglenol Orange Complex

Analysis for Np by Controlled Potential Coulometry
2.
3.

4.

6.

7.
8.
9a.
Sb.
- 10.
11.

12.
13.
14.

15.

16.

17.
18.
18.

Roberts /Choppin/Wild
page 4

III. Sunnéry nf Previous Plutenium Procedures
G. H. Coleman '
NAS-NS-3058 (1965)

Determination of Pu in Solutions Containing Large Amounts of

Fe and Cr
Separation and Determination of Pu by TTA Extraction

Separation and Determination of Pu rn\U Fission Product
Mixtures

Plutonium

Pluteonium

Separation of Plutonium from Uranium and Fission Products in
Irradiated Reactor Targets

Determination of Pu

Uranium and Plutonium Analysxs

Separation of Plutonium fram Irradiated Uranium

Separation of Plutonium from Uranium Metal

Purification of Plutonium from Uranium and Fission Products

Uranium and Plutonium £f£rom Envzronmental Samples of Soil,
Vegetation, and Water

Plutonium from Environmental Water Samples
Plutonium from Environmental Water Samples

Separation of Plutonium in Uranium-Plutonium Fission Element
Alloys by TBP Extraction from Chloride Solutions

Separation of Pu before Spectrographic Analysxs of Impurities
Anion Exchange Method .

Separation of Plutonium Before Spectrographic Anlaysis of
Impurities. Extraction Chromatcgraphy Method Using TBP

Separation of Np and Pu bj Anion Exchange
Separation of Rp and Pu by Caticn Exchange Chromatography

Dgtermination of Plutonium in Urine
20.

21.
22.

. 23.
24.

25.

" Procedure)

Roberts/Choppin/Wild
page 5

Suzzary of Previous Plutonium Procedures, continued

Determination of Pu?3?® in Urine (Small Area Electrodeposition
Determination of Plutcnium in Urine

Determination of Americium in Urine 1fi~the Presence of
Plutonium

Determination of Plutonium in Urine by Anion Exchange

Determination of Plutionium in Urine by Cocrystallxzatlon

with Pota531um Rhodizenate

Determinatiocn of Plutonium in Urine and Bone Ash by

Extraction with Primary Amines
Roberts/Choppin/Wild
page 6

IV. New liranium Pracedures

INTRODUCTION

Since the publlcatlon of the orzgxnal monograph on the radio-
chemistry of uranium in 1962, much attention has been given to methods
of separation, isolation, and measurement of small amounts of
uranium in various types of samples. Such samples involve geological,
biological, and environmental matrices, frequently of high complexity
and lcw uranium content. The procedures for such samples collected
in this monograph are meant not to supplant, but rather to supple-
ment those in the original mcnograph by allowing applicability of
the procedures to & wider variety of sample types.

These new procedures were chosen to provide description of
a wide variety of techniques rather -than to fccus on any particular
method, such as neutron activation anaiysis or solvent extraction.
Some of the procedures emphasize the separatzon of uranium from
other elements, while for others, the main focus is the method of
measurement.

A complete procedure generally can be divided into three
operations: 1) ‘sample preparation, 2) separation of the element(s)
of interest, and 3) analytical measurement. In many cases a
specific operation from one procedure can be used in conjunction
with other operations from anothe~ procedure. This should
allow a broad spectrum of sample types. For each of the collected
procedures, sample types to which the procedure may be applied
are given. A more complete discussion of each procedure and
additional informaticn regarding applications can be obtained
from the original reference. In some cases, additional references -
are listed, as they ~ontain similar, related procedures and might
be of interest in the case of some particular sa=mple.

DISCUSSION OF THE PROCEDURES -

The first twc procedures involve precipitation of uranium
from large quantities of water. In the first procedure, NaOH
is used to precipitate uranium from seawater. The efficiency
of recovery of uranium and other heavy radionuclides from 750
grams of seawater by this procedure is shown in Figure 1.
The dspendency of the recovéry efficiency on the volume of NaOH
added is evident, with maximum recovery occurring after addition
to tha 750 gram sample of at least 8 ml of 1.0 M NaOH, which |
corresponds to a final NeOH concentration of approximately 0.01 M.
For different volumes of samples, the amount of base to be added
should be modified so as to obtain a comparable NaOH concentration.
Figure 2 is an alpha spectrum of a uranium sample obtained from

the use of thigs method.
% RECOVERY

- | Roberts/Choppin/Wild
page 7

 

 

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L | | -
SO /

f e
i o Y

9 Po
i 22®am
- A?"Pu

. g . . 1 -~
° S
mi of L.OM NoOH

 

FIGURE I. Recovery of uranium (and other added
nuclides) from 750 ml of sea water with - ‘“cus
volumes of 1.0 H.NaDH added. (5ee Proci. -: ™ §
for reference),.
 

 

 

 

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at 238 u —_—) @
Z ,[ Y //i by
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X i F / j Q
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CHANNEL NUMBER

FIGURE 2. Alpha activities of natural
uranium plated directly onto & counting
disc from the dissolved precipitate of 740
grems of Scripps Pier sea water. (Note
the absence of other ectivities in the

4.0 - 5.7 MeV energy range). (See -
Procedure 1 for reference).

Roberts/Choppin/Wild
page 8
Roberte/Choppin/tiild
page S

The second procedure involves the coprecipitation of
uranium with iron potessium ferrocyanophosphonates. - This procedure
can be used with larger volumes (several liters) of water and gives
-a slightly better recovery in scme cases. ' '

Procedures 3 ang 4 involve sclvent extraction to preconcen-
trate and isolate the uranium. Procedure 3 uses tri-n-octylamine
(TOA) as extractant; details on the chemistry of this extractant is
described in the original uranium monograph (NAS-NS-3050). This
procedure employs spectrophotometric analysis-.of the urenium by
<he use of arsenazo III reagent, which has come” into wide use
since the publication of the first amonozgraph and is an excellent
reagent for the spectrophotometric determination of uranium.

I+ forms & brightly colored complasx with uranium (VI) and can be
used to detect uranium in the part-per-million range (and, in socme
cases, in even lower concentrations). The original series of
articles on the use of this reagent!”? should be read for details.

Procedure L also uses trioctylamine in the solvent extraction
~ of uranium from acidic agqueous media. This procedure employs
‘the use of 239U tracer to correct for the low (2 - 10%) uranium
yield. This isotope is convenient to use as a tracer since its
alpha decay energies (and these of its daughters) are above
. 5.8 MeV and therefore do not interfexre in alpha spectroscopy with
the peaks cf the more commonly encountered uranium isotopes.
The preparation of the 2%y tracer by irradiation of thorium is
also described in the procedure®. The alpha spectrum of the puri-
fied 3%y (and its daughters) is shown in Figure 3, in which the
separation frcm the alpha spectra of 3%y, 3%y, and 2'% ig
easily seen. Quantitative analysis of samples is obtained by .
alpha spectroscopy and an appropriate yield correction obtained
from the #?°U. Although the yield is low, this procecdure is
a useful one for soil whose complexity causes the low yield.

_ Procedures 5, 6, 7 and 8 involve ion exchange chromato-
graphy. Procedure S used Dowex-21K resin in either the malonic or
ascorbic acid form for the separation c¢f uranium from other metal
ions. This procedure is capablie of separating uranium from a
host of other metals, and is therefore useful for purifying uran-
ium from highly contaminated samples such as fission products.
Uranium forms ‘a stronger anionic complex with both maiosnate and
ascorbate than most other metals and is retained on the column
while other metals are preferentizally eluted with a series of
increasingly stronger eluting agents. Reported recovery is
excellent, S9% + 1%. Additionally, the procedure allows purifi-
cation of thorium, if it is present in the sample.

. Procedure 6 uses Amberlite XAD-4 resin, convertad to the arsoaic
acid form, to separate uranium from natural waters in samples of
up to one liter in volume. Uranium recovery is dependent on pH,
as shown in Figure 4. Recovery and separations from other ametal
ions is reported to be very good, with chromium(III) deing the
only interference. When present in equal concentration with
the uranium (0.5 ppm), approximately l1l1% of the chromium was
eluted with the uranium fraction.
Roberes; Choppin/Wild
pege 10

80

735

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Channe! Number

FIGURE 3. Alpha spectrum of purified 230y
in equiliggfim vith fits doughcers prepared
from the TR irradiation | rocess, showing
the energy separstion from other common
urapive isotopes. (Emergies given in MeV).
(Sze Procedure & for reference).
% RECOVERY

Roberte/Lhoppin/Wild

page i1

 

 

 

 

 

T T | )

80— ) &

0 /
50— / & A —
/° / o Th*¢
40 bwo : fij‘b a Fe+3 —
- 2
| ~ 8 LK%:
| &

201 o0 | - —
| 1 g L L L i ] I i
-3 -2 - O i e 3 4 5 &

o b

FIGURE &. Effect of pH of retenticmn of Th{Iv),

U{VI), and FE(IIL) on &n arsomic ascid columm.
(See Procedure & for zeference).
Roberta/Choppin/¥Wild
' page L2

In Frocedure 7, an initial column geparation using RDEH?
(di=-2=-athylhexylphosphoric acid) supported on 0.1 - 0.2 mm Teflon
seads is used both to isolate the uraniuz fraction from a sample
and to separate the individual U(VI) &and U(IV) fractions. The
separate f{ractions are purified by passage-through anion-exchange
resin columns prior to alpha spectromeiry. Large amounts of Fe(IIIl)
in & sample are reported to interfere with the separation.

- Bowever, reduction to Fe(Il) with hydrazine hydrochloride eliminates

this interference. '

: Procedure 8 employs a tetrahydrofuran-methy! glycol-HCl
pixture with Dowex-l anion resin to separate ura .am from acidified
natural waters. Quantitative analysis is performed bv optical
spectroscopy with arsenazo III. B

An increasingly important anaiyticel tool for alpha emitters
is employed in Procedure 3 wherein liquid scintillation alpha
counting is used to “etermine uranium in biological samples.
Instructions are give+: for t.~ use of both extractive and dispersive
scintillation cocktails. The cttractive cocktail gives slightly
lower background counts, and wcald probably be the more desirable
method for samples with lower uranium content. o

Procedure 10 is a neutron activation analysis for use with
solid biological materials. After irradiation, the uranium is
isoclated by solvent extracticn using HDEHP. The separated uraniux
is analyzed with a Ge(Li) detector by measurement of the 75 keV
gazmma ray of 2°°U. Reported yiei.ds are in excess of 90%.
Procedure 1l also describes a procedure of activation analysis.

in 196%, a procedure (reference 5} was published which quickly
became a leboratory standard for uranium analysis. Although it is
not really applicable to trace quantities of uranium, ner for
highiy radicactive samples, and has been supplanted by newer pro-
cedures, it is worthy of mention since it is still in common
use in many analytical laboratories. In this procedure, uranium
(¥I) is reduced to uranium(IV) by an excess of iron(II) sulfate
in a phosphoric acid-sulfamic acid solution. The excess iron(II)
is oxidized to iron(III) By nitric acid with a molybdenum(VI)
catalyst. The uranium(iV) is finally titrated with standard
potassium dichromate soluticn using barium diphenylamine sulfonate

as the indicator.

This procedure is applicable to solutions of 0-300 mg of
uraniwe per aliquot, with aliquot size up to about 15 ml. Optimum
uraniuz content is around 200 mg. There are relatively few inter-
ferences as compared with other redox methods, but vanadium,
bromide, iodide, and silver interfere directly with the redox
titrations of the U({IV). Additionally, if more than 100 mg of
of chromium{iII) is present, the indicator end-point <¢olor change
will be masked by the intense color of the chremium solution for
determination of trace levels of uranium in sclid samples by
neutron activation analysis in which no chemical separation is used.
lfihrtaldwpplnlflfld
page 13

REFERENCES

S. B. Savin, Talanta, 8, 673-685 (1961).
S. B. Savin, Talanta, 11, 7-19 (196%).

J. Hashimoto, K. Taniguchi, H. Sugiyama, and T. Sotobayashi,
Journal of Radioanalytical Chemistry, 52, 133-142 (1979).

W. Davies and W. Gray, Talanta, 11, 1203-1211 (196%).
Roberts/Choppin/Hild
pege 14

PROCEDURE 1

Semi-Quantitative Determination of Uranium
(e-Spectroscopy?

Source: V. L. Hodge, M. E. Gurney, Analytz,cal Chemistry, 47,

1866-68 (1975).

Sazple Type: Sea Hater

rrocedure:

1. Weigh 750 g of sea water into & 1 liter polyethylene bottle
{whose top h&s been cut_off).

2. Add 8 to 10 ml of 1.0 M KaOH while s*;rrzng rapidly with a
magnetic stir Dbar.

3. Centinue stirring for 1 hour, then allow the m;lky preczpztate
tc settle overnight.

4. Compact the precipitate by centrlfugxng the liter poljethylene

- bottle at 2500 rpm for 15 minutes (Note 1).

S. Pour off supernatant sea water.

6. Dissolve the precipitate with 2 ml of 12 M HC1l and add 3 drops
of 0.04% thymol blue indicator.

7. Pour the solution into a plating cell.

8. Add 1 ml of 12 H HCL and 2 ml of deionized water to the poly
bottle.

Wash the walls of the bottle with this soclution and transfer
~ to the plating cell.

10. Wash the bottle once again with 1.5 ml of deionized water and
transfer to the cell which has a stainless steel sounting
planchet as the anode. '

11. Neutralize the contents of the plating cell with 1.5 ml of
15 K NH OE to a pH of 2-3.

iz. Plate the sample at 0.% anp/cmz current density for 1 hour.

Basfore stopping the electrolysis, add 1 =l of 1S i WH, 08

to the cell. Dissemble the cell and prepare the disc for
counting by washing with water and acetone, then drying.
Count with & silicon surface barrier detecteor (the authors
reported using a 300-4S50 == 2 detector monitored by a pulse
height analyzer; counting times of roughly 1000 minutes)
{Mote 2).
Hote 1l:

Hote 2:

Roheftlehoppinlfiilfl
page 15

.__\ .

The reported precipitation efficiency for uranium
ig 86 ¢ 2% using 8 ml of 1.0 K NaOH to effect
préci~itation. Thies value can be us+d in calcul-
atione for semi-quantitative analysis, or a tracer
could be added (see the original arcicle).

Pu and Am are coprecipitated and ciplated with the
uranius. All three elemsnts are dentified and
measured by the alpha energy specircmetry. -
Roberes/Choppin/tilé
pege 16

PROCEDURE 2
Concentration of Uranium by Coprecipitation
with Iron-Potassiuk Ferrocyanophosphonates
Source: V. P. Kermanov, D. A. Fedoseev, Radzokhlm;ya, 18,
827-29 (1878).
Sample Type: Aquecus
Procedure:
1. To 5 liters of water containing uranium, add the following:

7 ml MIOMPA (monoisooctylethylphosphonic acid)
5 ml toluene

1.5 ml kerosene

100 mg potassium ferrocyanide

1.3 3 ferric ~hloride

2. Miz thoroughly for 15 minutes.
3. Filter the precipitate.

4. Transfer to a weighing bottle or metallic substrate.

Extraction efficiency: 93 ¢ 14%
Roberts/Cheppin/Wild
~. . page 17

PROCEDURE 3

Extraction of Uranina with TOA and Spectrophotometric
‘Determination with Arsenazo III

Source: K. Onishi, K. Sekine, Talanta, 19,473-78 (1972)

Sample Type: Acidic aqueous

Procedure:

Solutions: Thenoyltrzfluoroacetone, 6.5 o - dissolve us g
TTA in %00 ml of xylene.

Tri-n-octylamine - dissclve S g TOA in 100 g
of xylene.

Cresol Red - dissclve 120 mg of Cresol Red in |

26 m1 of 0.01 M NaOH and dilute to 250 ml with
water.

Aqueous Arsenazo III soluticn - 0.10% w/v,

The sazple containing 0-5 ug of uranium should be made to
a volume of about 20 ml and % ¥ in hydrochloric acid.

Transfer the sample to a 100 ml separatdry funnel and shake
for 10 minutes with 10 ml of the TTA solution to remove iron.

Allow the layers to separate and drain the aqueous phase
containing any U(VI) into a second separatory funnel.

Wash the organic phase by shaking for § minutes with 3 ml
of 4 ¥ HC1 and add this aqueous wash phase to the original
agqueous phase in the second separatory funnel.

Add 10 ml of TOA solution to the second separatory funnel and
shake for 2 minutes..

Allow the layers to separate and drain off the aqueous fihase.

Wash the organic phase by shaking for 2 minvtes with 3 ml of
¥ M ETl, and discard the aqueous phase.

Back-eéxtract the uranium by adding 10 ml of 0.3 M HCl to

' th. organic phase and shaking for 2 minutes.

Transfer the aqueocus phase to a third separatory funnel and
shake the organic phase Hith 3 ml of 0.3 M HCl for 1 minute.

Add this aqueous phase to the third se- aratory funnel and
discard the organic phase. .
1l.

12.

i13.

1s.

15.

Roberts/Choppin/Wild
pagn 18

Shake the aqueous phase for 1 minute with S ml of xylene.

' Transfer the aqueous phase (containing the uranium) to a

25 m) volumetric flask through filter paper.

Add 1 ml of 1% ascorbic acid solution. 1 drop Cresol Red
solution, and adjust the pH to 0.5-2.0 (solution turns
from yellow to red) with 1:9 dilute ammonia solution.

Add 1.0 ml of Arsenazo IIT solution and dilute t9 volume
with vater.

Measure the absorbance of the solution at 650 nm using che
reagent blank as a reference (an appropriate calibration
curve should also be constructed with standard uranium

solutions).

Note: The molar absorptivity for the uraniun(VI) - Arsenazo_
III complex used in this procedure is 4.4 2 107 1.mole™!

Reperted recovery of uranium for thzs procedure is approximately
99%.
Y
.. Roberts/Choppin/Htld
' page 19

PRCCEDURE &

Determination »f Uranium (and Plutonium) Isotopes
~.in Soil Samples by a-Spectroscopy

Source: J. Hashimotc, K. Taniguéhi.'n. Sujiyana, T. Sotobayashi,

Joeurnal of Radioesnalytical Chemistry, 52, 133-u2 (1979)..

Sample Type: Soil

1.

- Procedure: Preparation of 33jU tracer (done prior'to_deternination)

ThO, (free of uraniva contamination) is wrapped in aluminum
foiz and irradiategzuith a 50 MeV proton beam (total applied
current - 5.6 x 10 © coulomb).

Store the irradigtgd sample for ong month {allows maximum
accumulation of *'°U from parent (*’‘pa).

Dissolve the ThO, target in a mixture of HNO, and HC1 solution
containing a snail agount of KF. :

Evaporate to near dryness and convert to 8 M HC1l solution.

Purify the uranium fraction by anion exchange.

Procedure for Soil Samples:

1.
2.

Dry the soil sample in sunlighf, then crush to a fine powder.

Dry the powdered samples in an electric furnace at 110°C for
one day.

~ Pasg the sample through a 32 mesh sieve and weig~ a 50 g sample.

Transfer the samplc to a 1 lLiter beaker containing 200 ml of
8 M HNO,, and add a known activitiy of 23%y tracer.

Digest the sample with ultrasonic agitation for 2 hours, then
boil gently for a few hours. .

Let the sample stand overnight at room temperature, then filter

through glass fiber paper. -

.Concentrate the filtrate to about 100 ml under an infrared lamp.

Add several drops of 30% H,0,, and evaporate to near dryness.

Redissolve the residual substance in 200 ml of 8 M HNO, ana
filter through filter paper (No. 5A).
‘Roberts/Choppin/¥ild
page 20

Ixtraction rFrocecure:

1.

10.

. Note: Because of the relatlvely short half-life of

The extractant should be prepared as 10(v/v)$ TOA (Trioctylamine)

- in xylene and equilibrated with an equal volume of 8 !_HNO .

Noté: In the fullowzng extraction and washing steps, shaking
times are 10 minutes.

Extract twice with 50 ml of the TOA/r¥ylene e~ctractant and save
both organic phases. : . '

Wash the combined organic phase with 100 =l of 8 M HNO3 (to
remove ferric ions). -

Wash the organic phase with 100 ml of 10 M HCl (to remove
thorium).

Scrudb the organic phase (containing U and Pu) with SO ml of
distilled water and then 50 ml of 0.36 M HC1 + 0.01 M HF
solution. Collect both aqueous phases in a Teflon beaker.

Evaporate the combined aqueous phase under an nfrared lamp.

Decompose organic impurxtzes by repeatedly evaporating with
concentrated rlNO3 containing HC10, unt11 no fuming due to
HC10, occurs.

Dissolve the residue in 0.5 ml of 1 M HNO, solution.

Electrodeposit the U (and Pu) on a counting planchet using
10 m1 of 0.2 M amponium formate as the electrolyte and a current
density of 0.15 amp/cm’ for 50-6C minutes. .

Count the sample with a silicon surface barrier detector combined
with a pulse-height analyzer.

ZIOU

(ty = 20.8 4d), a correctzon for decay should be made.
Alternatively, *’°U activity could be calculated from
the activities of its daughter Th and granddaughter
222 Ra, which will be in secqular equilibrium with the
parent 2%y,

Uranium Yield: Reported as approximately 2-1i0% dépefiding
on a given soil sample.
Roberes /Choppin/Bild
page 21

PROCEDURE 5 |
Anion Exchange Separation of U in Halonic
and Ascorbic Acid Media

Scurce: M. Chakravorty and S M. Khopkar, Chromatographxaq 10,

372-76 (1977)
Sample Type: Aqueous solutions, fission products,aminerals
Procedure:
Column Preparation:

1. Pack a l.% x 18 cm column with Dowex-21K resin (50- 100 mesh),
cl” form)

2. Convert to the malonate or ascorbate form by paésing 150 ml
of 5% malonlc or ascorbic acid buffered at pH 4.5 through the
column.

3. Wash the column with water.

Sorption:

‘1. To a sample of appropriate volume (see note in the next step)
' ‘add 0 2 g of malon;c or ascorbic acid-as applicable.

2. Ad]ust the pH to 4.5 with 1 M NH OH and 1% malonic or ascorbic
acid as applicable.

Note: The total volume of sclution should be about 10 ml.

3. Sorb the solution onto the column (prevmously described) at
a flou rate cf 1 ml/mln. .

Note: In the following elution steps, a step may be omitted
if the indicated elements are not present in the sample.

Separation cf Malonic Acid HMedia:

1. T1(I), HEg(Il), Fe(III), Bi(IIX), alkalis, and alkaline earths
- are not sorbed onto the column and are eluted in step 3 above.

2, Hn(II), Co{IXI), Ni(II), Pd(II), Zn, and Cd are eluted thh water.
3. Sb(III), Fe(III}, Al, and Cr(III, IV) are eluted with 2 M NH,CT.
. Cu(II), V(IV), and Mo(VI) are eluted with 2 I NaCl.

5. PB(II) and Zn(IV) are eluted with 1 Elammoniuh acetate.
Roberts/Choppin/Hild
' page 22

Ceria earth lanthanides are eluted with 0.0S5 M HC1.

U is finzlly eluted with 1 M HC1.

If Th is present, step 7 is omitted and the Th is eluted with
100 =l of 0.25 M HHO,, and U eluted next with 150 ml of 0.25 M
HNO ..

3 .

Separation in Ascorbic Acid Media:

1.

Alkalis and alkaline earths are not retained on the column
ané are therefore eliuted in the original sample solution.

Cr, ¥n(II), Fe(II), Co(II), Ni(II), P4(IXI}, Zn, Cd, AL(III),
Sh(III), and Pb{(II) are eluted with 200 ml water.

Zr(IV) is eluted with 1 M ammonium acetate.
V(IV) is eluted with 1 b NH Br. |

Y is eluted with 0.1 K HCi.

Ti(IV) is eluted with 0.2 M HCL.

U is eluted with 1 M HC1. |

If Th is firesent, it can be éluted after elution of U with
3 M HC1.

If Mo is present, it can be eluted after the uranlum with 1:7
gmBoNnia containing 3% (NHE)ZSO

Note: Ia all cases (for both malonic and ascorbic acid media)
the volume of elutant is 200 ml, unless otherwise noted.

Yield: Reported yield is 99': 1%.
Roberts/Choppin/Hild
pege 23

PROCEDURE 6

Separatxon of Uraniuz from Heavy Hetals by Chromatography .
Using an Arsonic Acid Resin

Source: J. S Fritz, E. H. Moyers, Talanta, 23, 590-93 {1876).

Sample Type: Natural Haters
Procedure:

hcsin Preparation:

l.

2.

Wagh a quantity of XAD-4 nacroporous resin (150-200 mesh)
with acetone and concentrateé HCl.

To the resin, add a 60-%0 v/v mixture of éulfurie and nitric
acids at 0°C. Raise the temperature to 65-70°C for half a
day. to nitrate the resin.

Reduce to the amine at 7)-75°C by adding mossy tin in
concentrated hydrochloric acid (reaction allowed to proceed
for half a day),

Slufry the product with 1 M NalOE (te remcve tin salts).
Cool td 0°C in concentrated HCl.

Diazotize by slow addition of 1 M NaNo,.

Wash the resin with sodium carbonate sclution, and

convert the resin to the arsonic acid ferm with

sodium arsenite (in aqueous solution) at 73-75°C.

Pack a column (2.8 x 0.6 cm) with 0.5 g of the prepared resin.

Separation Procedure:

1.

Buffer the sample solution containing uranium(VI) (up to one
liter) to pH 5.8 wl. orthophosphorzc acid and ammonia and
make to 0.01 ¥ in EDTA.

Pass the solution through the resin column at 7 ml/min.

Wash the resin with 100 ml of 0.01 H EDTA buffered to pH
5.0 (with phosphoric acid and ammonia) -

Wash with 100 ml of pH 5.0 wash solution (no EDTA, no metals).

Strip the uranium from the column with 25 ml of 4 M HClOu.

Recovery: Uranium is successfully separated from other metals
by. this procedure. Chromium(III) gives & slight
interference (ca. 11% recovery). Uraniun TeCcovery
is reported at 98.3%. :
Roberts/Choppin/¥ild
page 24
PROCEDURE 7

Chromatographic Separation and a-Spectronetrzc
Detem:..nat:..on of Uranium

Source: R. V. Bogdanov, R. A. Kuznetsov, Racdiokhiaiya, 17,
S02-4 {1875). :

Sample Type: Acidic media, uranium content 1-100 ug
Procedure:
Column Preparation:

1. Column size is determined by sample volume and composition.
Linear flow rates up tc 10 cm/min are acceptable.

2. Teflon with 2 grain size of 0.1 - 0.2 mm serves as the
carrier. A 1l:1 solution of HDEHP (di(2-ethylhexyl)

phosphoric acid) in acetone is passed through the column,
and the solvent is then remcved by purging with air.

Initial Separation:

1. Pass the sample solution through the column (optimum solution
pH is 1-2).

2. Wash the column with 0.01 ¥ HCI.

3. Remove l-'e3+ (and some other elements) by washing with three
column volumes of & M HC1l at a flow rate of 2 cm/min.

%. Elute U(VI) with 12 M HC1 {six column volumes at a rate of
4 cm/min). .

S. Wasl column with water.
6. Oxidize U(IV) to U(VI) Hlth 15% Hzo2 (4=S coluxzn volumes).
7. WdWash the column with water and elute the U(VI) with 12 M HCl.
Note: Thorium is still on the coclumn at this point and can
be eluted with 6 M H Po or a solution of 0.5 M
C,0 +oesnl-dro
2 272 3°
"Purification:

‘1. Add one drop}of HC10, to each uranium fraction and evaporate

to dryness.

2. In a Teflon cup, treat the residue by adding 2 nx of 8 M HNO,
and evaporate to dryness.
10.

11.
12.

13.

lu.

RobértllChnppinIHild
page 25

Repeat the addition of 8 M HHO, and eveporate to a volume.
of 1-2 drops. - : -

Cocl the cup and add % drops of 8 K HNO,.

Tranafer to a 2 x 80 m® column containing AV-17 anion-
exchange resin in the nitrate for=z.

Rinse the cup and add the rinse solution to the column,
allowing the combined solutions tc pass through the column.

Wash the column with six column volumes of 8 M HNO, (to
renove nonsorbable elements).

Uranium is eluted with 10 columns of 1.5 g ENO,.

Add one drop of HC10, to the uranium solution and evaporate

to dryness.

After evaporation, treat the residue by heating with 1 ml
of 0.2 M HCl.

Evaporate to a volume of 2-3 drops and cool.

Add 6-8 drops of ethanol and ‘ransfer to an electrodeposition
cell.

Repeat the treatrent with 0.2 M HC1 and transfer this solution
to the cell. A current of 40-%50 mA for 2 hours is used for
electrodeposition.

Aftér electfolytic deposition is completed, the solution

is remuved rapidly and the cathode disc is washed, dried
and counted with a surface barrier detector.

Notes:

}. The method, when carefully executéd; gives a uranium

yield of 96 + 3%. For more precise work, a ?'%U tracer
can be added to the original sample.:

2. Substantial amounts of Pe'+ have an adverse effect on
the separations, so iror. should be reduced to Fe? with
hydrazine hydrochloride in samples of high ircn content.

3. The cell is a Teflon cylinder of 16 mm diameter and a
height of 35 mm. The cathode is a counting planchet of
Ni or Cu; the platinum anode is positioned 15 mm above
this cathode.
Roberts/Choppin/Wild
page 26 '

PROCECURE 8

Cetermination of Uranium in Natural Waters
After Anion-Exchange Separation

Source: J. Workisch, L. G¥dl, Analytica Chimica Acta, 71,
113=-121 (1874).

Sample Type: Naturel wvaters

Procedure:

Solution Preparation:

1. Pretreatment soiution - add 1 ml of concentrated HCl to

" - 100 ml of distilled water. In this solution dissolve 0.5 g

of ascorbic acid and 1 g of potassium taiocyanate.

. Kote: This solution should be prepared a few hours prior
to use and has & shelf-life of only 2-3 days.

2. THF - MG - HCl mixture - 290 ml of sclution should be
prepared per separation, and larger quantities may be
prepared since this solution has a indefinite shelf-life.
The mixture is prepared to be 50 veol.% tetrahydrofuran
(THF), 40 vol. § methyl glycol (MG - monomethyl ether of

ethylene glycol), and 10 vol. % in S ¥ HC1. Tais solution
should be prepared at least several hours before use.

Column Preparation:
1. & g of Dowex 1 (Bio-Rad AG 1-X8, 100-200 mesh, chloride form)
‘anion-exchange resin is slurried with a2 few milliliters of

the pretreatment solution (described above).

2. After allowing to é;find for 15 minutes, pour into an
appropriate size column. .

3. Wash the resin with 50 ml of the pfetreatment solution.

Séparation Procedure:

1. .To.a 1 liter water sample, acidify with 10 m1 of concentrated HCl.
2. Filter through a dense filter.

3. Add § g of ascorbic acid and 10 g of potassium thiocyanate.

4. Mix thoroughly until all reagents have diss&lvéd.

5. Allow to stand 5-& hours.
7.
s.
9.

Roberts/Choppin/uild
page 27 .

Filace the sample solution on the column and allow it to
pass through at a2 rate of 1.2 - 1.3 ml/min (correspondxng _
to the back.pressure of the resin bed).

Wash the column with 100 =l of the THF-HG-BCl mixture.
Wash the column with 100 ml of 6 M HCl1. -

Elute the uranium with 50 ml of 1 M HCI.

Determination of Uranium:

1.
2.

Prepare an aqueous 0.1% solution of arsenazo III.

Evaporate the uranium-containing elute to dryness on a stea=
bath.

‘Take up the residue in 5 ml of 9 M hydrochloric acid (added

in portions) and transfer to a 50 ml wide-neck Erlenneyer
flask.

Add exactly 0.550 g of zinc and cover the flask loosely
Wwith a stopper.

Shake the flask carefully until all of 2= zinc is dissolved.

Immediately add €.15 g of oxaric acid and 0.5C ml of the |
arsenazo III solution. _

Measure the absorbance of the solution of 665 nm against a
reagent blank prepared in the same manner.

Prepare a calibration curve (1-13% pug of uranium range) and
obtain the sample uranium conceintration by comparison.

Note: The absorbance will remain constant for at least
30 minutes. The following articles contain related
information on this preccedure and its development:

"Deterzination of Uranium in Geologic Specimens

after the Separation of the Uranium by Anionic '
Exchange™ by J. Korkisch and I. Steffan, Mikrochimica .
Acta, 1972/6, 837-860 (1972). T"Determination of Small
Amounts of Uraniun after Coricentration by Extraction and
Anionic Exchange in & Tri-n-octylphosphine Oxide Solvent
System”™ by J. Korkisch and ¥. Koch, Mikrochimica Acta,
1973, 157-168 (1973). "Anicnic Exchange Separations of
Elements which are Extractable with Tributyl Phosphate
VII™ by J. Korkisch and ¥. Koch H;krochxnlca Acta,
1973, 865-875 (1973).
Robarts/Choppin/Hild
page 28

PRCCEZCURE S

Uranium Analysis. by Liquid¢ Scintillation Counting

Source: W. J. McDowell, J. F. Weiss, Health Physics, 32,
73-82 (1977).

Sample Type: Bone and tissue samples. (This procedure can
be adapted te other sample types; these modified
procedures are referenced).

Procedure:
Sample Preparation:

1. A. For small bone or tissue samples (<25 g), dissolve in
concentrated nitric ac*d with a smell amcount of 30%
H,0, added. |

B. Heat gently until a clear sclution is obtained. (In
samples with small amounts of residual salts, do not
allow to go dry). |

2. A. For large samples (>25 g), dissolve by repected treatment
‘with HNO, {(conc.) and 30% H,0,, evaporating to near dry-
ness between each treatment.

B. Heat the sample to 450°C in a furnace cvernight.

C. If the resulting ash is not white, repeat the acid
- digestion and heating until a white ash remains.

D. Dissolve the ash in a suffirnient volume of 2 M HHO, .

3. Depending on the cocunting method to be used, further treat-
ment at this point varies:

A. For samples to de treated by anion exchange separatiqn,
dilute or treat the sample solution accordingly to give
the desired nitric or hydrechloric acid concentration.

B. For high activity samples to be cocurted with an aqueous-
phase-accepting scintillator, dilute the sample to
a known volume and add an aliquot to the scintillator.

C. TFor samples to be counted with an extractive scintillator
containing HDEHP. addé sufficient perchloric acid to the
sample solution to give & final solution which is 0.1 -

0.2 M HC1l0, and in which all metal ions have been converted
to perchlorate salts. (Observe the usual precautions

for adding HC1lC, to 2 solution containing small amounts

of organic material). The nitric acid is evapoirated at
slightly higher heat (150-170°C} in order tc leave only

e —— e et e
Rob:rta!ChoppinlEild
page 29

the perchloric acid and salts. Add 2 =zl of saturated
£1(KO,), per gram of sample to the hot scluticn and
adé witér to make 3 ml of volume per gram of sample.

Counting in All-Purpose Scintillator:

160 g naphthalene
10 g PPO 72,5-ciphenyloxazole) |
8.1 g POPC> (2,2-p~phenylene-bis-S-phenyloxazole)
385 m1 =wylene |
385 ml dioxane
233 21 ethyl alcohol
180 m»l Triton X-100

Up to 1 ml of aqueous sample sclution mfiy be taken up in
the scintillator (volume approximately 15 ml).

The alpha peak of interest must fall within the pulse-height
range observed. This can be determined two ways:

~A. The peak may be located by counting through a narrow-ra:; e

window and scanning across the entire available .range.

B. A smultichannel analyzer can be connected to the scintilli-
ation counter. (This technique has the additional benefit
of allowing visual differentiation of the alpha and
beta-gamma spectral.

Unless each sample has a very similar matrix, the alpha peak
position must be determined for each sample tc maintain
reproducible counting efficiency.

Typical background count rates run about 20-30 cpm with an
additional 10-20 cpm (from %0K) per each gram of tissue in
a sample. The practical lower limit for counting should
be 2 total count of at least twice the background.

Counting in an Extractive Scintilliator:

Extractive Scintillator:

1

161 g HDEHP (di{2- ethylhexyl)phosphorlc ac1d)
80 g naphthalene
b g PBBO (2-u'-biphenylyi- 5-phenylbenzoxazole) or
S g PPO (2,5- dlphenyloxazole) | _
liter toulene |

Transfer the sample (prepared as described under part 3.C. of
the sample preparation section) to a standard 20-ml scxntlll-
ation vial.
o

Roberts/Cheppin/Wild
psge 39

Add 16 mi of the extractive scintillator and shake for L
o 1 minutes. - ' '

Allow zhe phaseé to separate (removal of the aqueous ph&se
is not necnssary, however) and place the vial in the counter.

A background count rate of 15-20 counts/ainute from external
sources is generally the lower limit for the extractive -
scintillator proceduve. _

Alpha energies differing by more than 1 HeV may be dzstinzuxsh-
able since typical full peak width at half maximum peak height

is typically 0.9 - 1.0 MeV.

Note: The author describes a high resolution alpha scintill-
ation counting system in this paper and the one refer-
enced below. With that system, increased resolution
of complex mixtures is possible. Reported peak half-
width is 0.2 - 0.3 MeV and an energy identification

to :p.l_Hev.
Related Articleé-

W. J. McDowell, D. T. Farrar, M. R. Bxllzugs, Talanta,

21, 1231-1245 (197“)
5. L. Horrocks, Nuclear Instruments and Xethods, 117,

589-595 (187%).
Roberts /Choppin/Wild
: pame3l

PROCEDURE 10

Determination of Trace Uranium in B;ological Haterxals by
Heutron Activation Analysis and Solvent Extraction

Source: D. A. Beckar, P. D. La Fieur, Analytical Chemistry, us,
1508-1811, (1972).

Sample Type: Solid biological materials

frocedure: | |

Irradiation:

l. Lyophilize and sfiorfi-the samples in a dessicator before use.

2. Weigh the samples (200-450 mg) and encapsulate in a cleaned
polyethylene snap-cap vial.

3. _.Encapsulate an uranium standard (a solution of NBS Standard
Reference materizl No. 950a Uranium Oxide (Uaoa), 99.9u%
purity), consisting of 1 ml of 1.02 um U/ml.

. Attach copper foil flux monitors to all sanples and the
standard for flux normalization.

S. Irradiate the samples and standard (the authors used thermal
neutron fluxes of 1.3 x 10! ccm *sec ® and S x 10!’ n -

cm~ sec ! for periocds of 10 seconds to 5 minutes.
Dissolution:
1. Add 100 ug of uranium carrier to the samples.
2. Wet ash the samples with mixed nitric and perchioric acids

(observing the usual perchloric acid precautions), and 1-2

mg of vanadium as a catalyst. 1-2 mg of chromium should
also be added to indicate when all of the organic matter

is destroyed. The green-orange Cr(III) - Cr(IV) color change
‘usually occurs in 6-1C minutes. '

3. Ccol the samples, and dzlute to 20 ml with 9 M HNC The
final sample solution should be ca. 8 M in HN an in
HC10,, . - - |

Exzraction:
Note: The extractions are done in 35-ml polycarbonate centri-

fuge tubes using 0.75 M HDEHP. (di-(2-ethylliexy)-phos-
phoric acid in petroleum ether.
.--J

Roberts/Choppin/Wild
page 32

Add 10.0 =1 of HDEHP solution to the sanp;e in the centrifuge
tube and shake vigorously for 60 seconds ,

Centrifuge the samples for 2 minutes to separate the phases.

2.

3. Remove the aqueous phase with a disposable pipet and discard.

. Wash the organic phase at least once with 8 ¥ HNO, and
discard the wash solution.

5; Strip the uranium from the organic phase with 14 M HF,

' shaking vigorously for 1-2 minutes.

6. Remove the aqueous phase {(or an aiiquot, depending on

: acti.ity) for courting.

Counting:

1. Counting is performed with a large volume Ge(Li) detector and
4096 channel pulse height analyzer to measiurs the 75 keV 239y
gazma ray. .

2. A small aliquot (50-250 ul) of the vanadium standard is

diluted to an appropriate volume (corresponding to the
final volume of the samples to be counted). During this
dilution, several milligrams of dissolved inactive wranium
carrier should be added to the standard solution to prevent
loss of the radiocactive uranium.

Yield: 31 + 4%, Slightly higher yields =ay be obtained
by using separatory funnels for the extractions -
(for lower mechanical losses), bu* this method
increases the time required for phase separation.
Ecberts /Cheupin/Rild
sage 3]

PROCEDURE 11

Determination of Trace Uranium by Instrumental
Neutron Activation Analysis

Scurce: §S. Katcoff, Fifth International Conference on Nuclear

?EEEOds in Environmental and Energy Research, April 2-6,

‘Sample Type: Solids

rrccedura:

1.

Seal 0.3 - 0.9 g of solid sample (powdered, granular or bulk)
in carefully cleaned high purity quartz ampules 6 mm in diameter.

Irradiate. samples, standafds, and blanks for about 4 hours at
a neutron flux of 2 x 10!* n/cm? sec, and allow the ampules to
cool for 2-3 days. '

Remove activated @mpurigies from the outer surface of the
quartz by successively immersing the ampules briefly in
E:ffi:ntrtted HF solution, hot concentrated HNO,, and distilled
Before counting, placé each ampule in a cylindrical lead
shield 3.8" long, with 1.0" thick walls anc¢ a central hole
0.25" in diameter. This shield suppresses low energy gammas
which could interfere with counting. '

Count tiie sampie with a Ge(Li) detector connectec to a multi-
channel analyzer. A 0.5" thick lead absorber can be placed
between the lead sample contairer and the detector head to
further reduce low-energy interferences.

Uraniun can be. determined by measuring the activity due to

the high .i2ld fission products '’?Te (th = 78 hr.) and

188p. (¢4 = 12.8 d}. The '“?Ba decays to !*’La, which emits

a 159u-keV gamma. See the following table for relevant nuclear
cata.

 

Isctope Crcss | Selected
Element Mon.tored Sec-ion (barns) gamna (keV) % decay
U - Isipa 0.26 1595 Q¢
1327e o 0.28 773 79

Note: CEnough cooling time must be allow-+ for !'**La procduced
by the (r. ¥} reacticn of lanthanum in the sample to decay
away bef:..re counting. '
Roberts/Choppin/Wild
page 3u

V. New Keptunium Procedures

INTRODUCTION

Neptunium is usually encountered zs “*7MNp (t4 = 2.1% x 10%y)
in acid solutions of uranium reactor fuel elements. Neptu-ium-237
is of relatively little use commercially except, pessibiy, for
the production of pure sources of ?*°Pyu (by reactor neutron irrad-
iaticn) and of ?°*U (the a-decay granddaughterof 2!’Np). The
amount of #*’Np in the environment generally is so small as to be
unmeasurable as compared to ?!®Pu, and no procedures were found
for separation of Np from environmental samples.

~Neptunium-239 is a transient species in reactor fuel elements,
due to its short half-1life (2.35d). It completely disappears
shortly after the end of a neutron irradiation through decay to
23%Pu. Neptunium-239 is most frequently used as a tracer to study
the chemistry of Np; it can be obtained from the neutron irradia-
tion of ?*°U or by milking a sample of **’Am with which it is in
equlilibriur as the a-decay daughter. -

Two procedures are described for the separation of Kp. The
first involves separation of #?°Np from irradiated ?3°U, and the
second involves separation of 2?’Np from a solution representing
that from a dissolved fuel element. .
Roberes/ChonpinfWild
pagfi 35

 

<y

Chrowatograephic Separeation of Heprtunium Using
Quaternary fimfi@nlum Hitrate Extractant

Source: ¥. K. Harkov, A. . Usolkin, and A. 1. T@rm@vékiig
Rediokhimiya 21, 862 (1%733.

@ Type: % 100 =g sample of mixed uraniuzm oxides which has
peen irradiasted with a neutvon filux of 18'%f n/em?
for one day to produce 2°*%HNp.

E:fl
e
@.-— #

?.N ]

roepare & & oam dlamabhr@fiatogrfiphac eolumn by mixing V-8 mg

@f methyltricctylemmoniun nitrate with 800 mg of fluorocarbon
nowdey f(grain size of 150-280 um) and pouring the miwture into
the column. Flush the column with @ ¥ HNO,.

 

2. pissolve the uranium oxide sample in 5 ml of ¥ M fififig with
| heating.

&ad encugh ferrous sulfamate to the cooled soluticon to make
a concentration of 0.01 K.

€ad
s

&, Allow the solution te cool and pass it through the chromato-
gvaphic column.

5. Wash the ceclumn with 8 m} of Z K HNO,.

5. TFlute the 2°%¥p from the column with 6§ ml of a solution 0.03 H

Use a fiow rat@ of

 

in smponiuwn oxalate and 0.2 H in HMC

abcut 1 ml/min. 3

Note: Ho redicchemical yield is given, but it is indicated
that the extraction of Hp from the uranium is virtually
guantitative. = Gamma-ray spectra of the **°Hp product
show no v rays characteristic of flSSl@& -product
contamination.
Roberts/Choppin/¥ild
page 16

PROCEDURE 2

& Snpact rophotometrlc Method for the Determination
£ Neptunium in Process Solutions

Source: P. R. Yasudeva Rac and S. K.'Patil, J. Radiocanal. Chenm.
32, 399 (1978).

Sample Type: 5 ml of a 1 M HNC., solution containing about 100 mg
U, 0.25 mg Fu,. and 0.50 mg Zr in addition to -1 ug/ml
of 'Np. .

Procedure:

i. To the sample solution in a test tube add a known amount of
23%Np tracer solution (Note 1).

2. Adjust the solution to 0.1 M in each of ferrous sulfamate and
hydroxylamine hydrochlorzde.

3. Add S ml of 0.5 M thenoyltrlfluoroacetone -(TTA) in benzene and
- shake for 10 min with a vortex mixer to extract Np(IV) into
the organic phase.

N, Pipet 4 ml of the TTA phase into another test tubg containing
10 ml of a solution 1 ¥ in HNO and -0.1 M in Fe ? and
hydroxylamine hydrochloride (Ndte 2 ). '

5. Shake for 10 min to remove Pu(lV) extracted along with the Np(IV).

5. Remove the aqueous phase and add 1 ml of 8 M HKO, to the
organic phase. Shake for 10 min to extract the ip(IV) xnto the
aqueous phase.

7. Separate the ‘aqueous phase containing the Np(IV) and evaporate
to dryness.

- 8, Redissolve the Hp(IV) in 10 ml of & solution 0. 1 M in HNO,
and ~0.1 M in each of Fe *2 ana hydroxylamlne hydrochlorxde.

9. Add 5 ml of the TTA solution in benzene and reextract for 10 min.

10. Separate the organic phase, discard the aqueous phase and
strip the Np(IV) into 5 or 10 ml of 5 M HNO., containing
§ mg/ml of sulfamic acid and 0.1 mg/ml Arseflazo III.

11. Measure the optical density of the solutio’ at 665 nm with a
Beciman DU, using 1 cm fused silica cells. Compare with the
absorbance from a blank solution of S M HNO, containing S
mg/ml sulfamic acid and 0.1 mg/ml Arsenazo i11. Heasure
the chemical yzeld by comparing the y activity of the 23%p
in the sample against that of a known solution of 2394p (Note 3).
Kote 1:

Hote 2:

Note 3:

Reberts/Choppin/Wiid
page 37

23%4p can be obtained by either irradiating *'°y

in a reactor or by milking it from a sanple of
293 am (as the c-decay daughter).

Only % ml is removed to avoid inclusion cof any
aquecus phase. |

Beer's law for the Np(IV)-Arsenazo III complex holds
at least up to 1.5 ug Hp(IV) per ml; if H.PO

is added To the absorba.ce solution to madk %ha
Arsen&zo III ccmplex with Zr, a separate cali-
bration curve for measuring the Np(IV) absorbance
using H3P0 must be obtained.
Roberts/Choppin/Hild
page 34

VI. - Nev Plutonium Procedures

INTRODUCTION

Since 1965, when the original sonograph on the radiochemistry
of plutonium was published (1), significant changes have occurred
in the radiochemical separation and determination of plutonium.
Since the advent of a worldwide interest in ecology in the early
. 1970's, much attention has been directed at deteraining plutonium

concentrations in the enviromment: human and animal tissue,
plants, the atnosphere, and natural waters. These neasurements
involve the detection of extremely small concentrations of Pu in
relatively large matrices; e.g., liters of water or kg of tissue
or soil and sediments. This requires the reduction of the sample
and the quantitative concentration of the Pu to attain measurable
levels of activity free from interfering activities often in
s;gnxfxcantly greater amounts (e.g., natural uranium and thorium
and their daughters). _ .

Separat;ons procedures have been improved since 1965 by an
increase in the number and quality of solvent extraction reagents
which are available commercially. Many of the procedures presented
in the original monograph employed a solvent extraction step for
the purification of the Pu activity; most of these used either
thenoyltrifluoracetone (TTA) or tri-n-butylphosphate (TBP).

. Now available are such reagents as di-(2-ethylhexyl)orthophos-
phoric acid (HDEHP), trilaurylamine (TLA), tri-n-octylphosphine
oxide (TOPO), and tricaprylmethyiamine (Aliquat-336). Counting
methods have similarly improved with the introduction of the
silicon surface-barrier detector for a pulse-height analysis,
replacing the more coaplicated and cons;derably more expensive
Frisch grid with essentially nec loss in counting efficiency or
peak resolution. _

The proliferation of nuclear power reactors throughout the
world since 1365 has also led to the development of a great many
procedures for the separation of Pu in macroscopic concentrations
from other actinides and fission products resulting from the
dissolution of vranium reactor fuel elements. These are rot
considered among "he procedures for this monograph since they
generally do not Jend themselves well to a laboratory-scale
separation, but rather are relevant to a processing-plant
. operation with all the attendant precautions against radiation
hazards and leakage of radicactivity into the environment.

DISCUSSION OF THE PROCEDURES

The procedures presented herein reflect the interest in
messuring plutonium concentrations in the ecosphere arising prim-
erily from two sources: fallout from the large number of atmos-
pheric nuclear weapons tests conducted prior to 1363 by the Unzted
~Roberts/Choppin/wiid
: page 139

States, the United Xingdom, and the Soviet Union and, in

then, by the Chinesa and the French; and the int$odueti:=n::
szall amounts of Pu to the environmunt through the discharge

cf decontaminated low-level waste solutions by processing plants
and other laboratories employing radiochemical techniques.

With the exccgtion of Procedures 7 and 9 the fellowing
methods a2ll use solvent extraction, by either batch separation
or column chromatography, as the main purification-concentration
step. Procedures 1 - 7 use electrodeposition of the sample
followed by ¢ pulse-height analysis3 for the Pu deteraination;
procedure 8 uses absorption spectrophotometry and procedure

. 9 uses standard scintillation counting. Electrodeposition is
generally carried out from a solution of ammonium chloride or
ammonium sulfate; procedures 1-6 offer 'semi-detailed descriptions
of the process. See the Reference 1 for 2 more detailed des- '
cription of the electrodeposition cell and conditions affecting
the plating of Pu onto a metal disk. Occasionally, Pu in warm

or hot HNO, can be oxidized to the VI state which is no- retained,
subsequentiy, on an anion resin column. The use of NaNO, in -
.these procedures ensures that Pu is present in oxidation state

III.

A word of caution: at higher pH values (> &), Pu(IV) tends
to form a hydroxy-polymer which cannot be easlily destroyed and
which behaves differently from Pu species in higher acid con-
centrations. Methyl red indicator, used for adjusting the salt
and acid concentration in the electrc:lating solution, has a pH -
range of 4.4-6.0 for the equivalence point color change. If the
solution remains tco long at the yellow (basic) color, this
hydroxy-poiymer of Pu could form, thus severely reducing the
electroplating yield. Tne use of methyl orange (pH range 3.1-4.4)
as an indicator might serve to alleviate this potential danger.

Much recent research in plutonium chemistry is reviewed
in the papers in Refergnce 2.
REFERENCES
1. K. W. Puphal and D. R. Clsen, Anal. Chem. &&, 284 (1972).
2. "Plutonium Chemistry”, ed., W. T. Carnall end 6. R. Choppin,

ACS Symposium Series 216, Am. Chem. Soc., Washington, D. C.,
1983. o
Knberts/Choppin/wild
page 40
PROCEDURE 1

Lifiuid-Liquid Extraction Sepafation
and Letermination o7 Plutoniux

Source: R. P. Bernabee, D. R. Percival, and f. D. Hindman,

Anal. Chem. 52, 2351 (1980).

Sample Type: Soil Samples (1-10 g}, filters, anc water samples

(< 0.5 2) which have besn decozposed and leached.
The lanthanide-actinide species have been carried
on a precipitate of BaS0O, (see :zfs. a and b fecr
a description of the Bas , Precipitation procedure),

Procedure:

l.

2.

Transfer the BaSO, precipitate with a suitable amount of Pu
chemical yield tracer to a porcelain or platinum crucible.

Add 30 2l of 72% HC1l0, and dissolve the BaS0, with a minimum
amount of heating. Cool the solution *c room temperature.

Transfer the solution to a 60 ml separatory funnel containing
10 ml of 15% HDEHP in n-heptane. Extrac:z for S min.

Wash the organic phase twice with 5 =l portions of 72% HCly,.

Strip the .lanthanides and actinides frcz the organic layer
with two 10 =l portions of 4 M HNO, for Z min each; the first
10 ml portion should contain I ml 3f a 235% NaKNO, solution.

Wash the organic layer for 2 min with a solution containing
10 ml of ¥ M HNO, and 2 ml of a hydrazine-sulfamic acid
solution (Note li.

Strip the plutonium from the organic phase for S min with a
solution containing 10 ml of ¥ M HRC.,, 2 a1l of hydrazine-
sulfamic acid solution, and § mi of 0.2 ¥ di-tert-butyl-

hydroquinone (DBHQ).

Repeat the stripping process for 5 min with just 10 m}l of
B M HHO3 and 2 ml of the hydrazine-sulfarmic acid solution.
Combine“the strip solutions. .

Transfer the strip solutions to a second 60 ml separatory
funnel containing 10 ml of 15% HDEHP in n-heptane and extract
for 2 min to remove minor activities of Th and Pa. Acd

S ml of DBHQ solution to the combined orga:iic and aqueous
phases in th2 separatory funnel and shake for 5 min more.
11.

wa)

(b}

Rebepesf{Chenpin/Wild
poage &k

Tranzfer the strip (agquecus)scluticn to e 250 =1 EIrlenmeyer

flask containing 2 ml of conc. K,S0,; 100 mg of HaH50,, and
S 1l of an equi-volume mixture of ¢ nc KECl and conc. HHOa.
Hez< gently until the solution turns yellow.

Add an additional S ml of the egqui-~-voclume mixture of conc.
HCl and conc. HNC, plus 1 ml of 72% HC1l0, and evaporate the
solution to fumes of sto

Heat the flask over a Meker burner to a mild pyrcsu.fate fusion.

Cool the residue and dissolve in 1-2 ml of 6 ¥ EClL with heating.

Add 2 drops of a 1 M solution of the ammoniue salt of di-
ethylamznetrxamlnepentaacethc acid {DTPA) and evaporate until
only 2-3 drops remain (Kcte 2?!.

Transfer the saaple to the electrcplating cell with warz
rinses of 4% oxalic acid solution totaling 1i¥% ml. Add

1 drop of saturated hydroxylamine hydrochlorlde solutlon, and
2 ml of saturated NH Cl solution.

Stir the solution in the cell and add conc. ammonia drop-
wise until a red color persists for 30 sec. Add 3 drops of
€ M HE.

Electroplate for SC min at 0.75 A/cm?, add 2 ml of conc.
ampmcnia just before the end of the electrodeposition.
Dismantle the cell, wash the planchet with distilled water
ané alcohol, and dry the disk on a high temperature hotplate
for 5 min to volatilize any. remaining ?'°Po. Determire

the Pu isotopic composition and chemical yield by G=-spec-
troscopy (Note 3).

Kete 1: Prepare the hydrazine-svlfamic acid solution by
adding 10 mi of 85% hydrazine to 50 ml of 2 M
sulfamic acid sciution.

Note 2: The DTPA suppresses the hydrolysis of Pu at the
higher pHs.

Nocte 3: Chemical yields are typlcallv -90% with decontamin-
ation factors of 10°-10° from other a-emitting
species.

REFZRENCES

C. W. Sill, X. ¥. Puphai, ard F. D. Hindman, Anal. Chem.
46. 1725 (197&)

C. W. Sill, Anal. Chem. 49, 618 (13877).
Roberts/Choppin/wild
pege &2

PROCEDURE 2.

Letermination of Plutoniums in Sedinants'by Solvant Extraction

Source: N. P. Singh, P. Linsalatae, R. Gentry, and M. E. Wrenn,

Anzl. Chim. Acta 111, 265 (1979).

Sample Type: River-bottom sediments.

Procedure:

1.

Dry the sample in air. “rush to unlform particle size, and
weigh out a 20 g aliquo%. Aadd 2-3 adpm of **?Pu tracer
(Note 1) to the surface of the sedxment sample in a fused
quartz baking dlsh.

Heat sample in a muffle furnace at 400°C for 24 h to destroy
organic matter; cool to room temperature.

Leach the sample with 400 ml of a solution of 3 parts conc.
HNOE and 1 part conc. HCl. Filter the sample through Whatman

2 paper.

Repeat step 3, combine the. leachat=s, and discard the sedxnent
residue and filter paper. .

Boil the leachates down to a voluue of 100 ml, cool, and
dilute to 300 ml with distilled, deionized water. Precipi-
tate iron hydroxxde by the slou, careful addition of
concentrated ammonia solution.

Centrifuge the precipitate and discard the aqueous supernatant.
Wash the precipitate with dilute ammonia solution (-1/20 of
congentrated) as many times as is necessary to eliminate

so“ as determined by adding BaCl2 to a few rl of the

washing supernatants.

Dissolve the precsztate in a ainimum volume of conc.

HNO,. Add -200 mag of NaNO,, heating the solution gently.

Cool the solution to Zenperature and adjust the acidity
of the solution to 8 !_by adding conc. HNC,.

Transfer the solution to a 500 =l separatory funnel. Add an
equal volume of 20% trilaurylamine {(TLA) in xylene, which
has bsen preequilibrated with about 20 ml of 8 M HNO,.

Shake gently for about 10 min. Separate the phases, remove
and set asids the organic phase. Extract twice more with
equal volumes of TLA-xylene. Discard the aquedus phase.
10.

1l.

12.

13.

1%,

15.

1€.

Roberce/Chappin/iild
pege 43

cdmbina the organic phasgs inte the separatory funnel. A44
an equal voluse of 10 M KCl and shake gently for S min to
remove treces of Th. Discard the agusous phase.

Shake the ofganic phase twice (5 min eech} with equel volumes
of 8 M HNO; to remove uranium. Discard the aqueous phases.

Back-extract the piutonium with &n equal volume of 2 M nzsou.
cabi

. shaking gently for 10 min. Repeat twice more and c

the aqueous back-extractant soluticns in a beaker.

Evaporate fha back-extractant solutibn to dryness &nd cool.
Destroy residual organic matter by adding several drops
of conec. EHO3 and 20% nzoz; evaporate to dryness.

Dissolve the residue in 1 ml of 2 K H SD and transfer to &
plating cell. UWash the beaker twice Eore with 1 ml portions
of 2 H H,S0, and transfer these to the plating cell.

Add 1 drop of methyl red incicator. Add conc. ammonia dropwise
until a yellou color appears. Quickly add enough drops of

2 M H,S to restore the red color and electrcoplate at a
fi 3f 1.2 A for one hour.

Quench the electradeposition with 3-4 drops of conc. ammonia
at the end of the plating porcess; rezove the planchet and
wash with distilled water and alcohol. Flame to redness over
a4 Bunsen burner. Use a-spectrometry to determ;ne Pu isotopic
composition and yield (Note 2). .

Note 1l: Uranium in the sediment nay accompany the Pu -

' through the extraction procedure in amounts .
sufficient such that the 2%°U a-peak at 4.77 MeV
may interfere with the %®%py ,0-peak at 4.90 MeV.
If this is the case, more %*?Pu tracer than that
indicated must be added.

Note 2: The average Pu chemical yield for 1l measurements
was 35%, with a range of 7 to 71%. Amounts of Pu
down to a few pCi per dry kg of sediment can be
measured.
Robe -t : /Choppin/Wild
cage 44

PROCEDURE 3

Radiochemicel Determinati:-n of Plutonium in Marine
Samples by Extruction Chromatography

Source: A. Della Site, U. Marchionni, C. Testa, and C. Triulzi,
Anal. Chim. Acta 117, 217 (1980).

Sample Typss: (a) sea water; (b) sediments; (é) marine organisn#

Procedure:

1. Prepare two extraction slurries by adding dropwise, with )}
stirring, 2 ml of 0.3 M tri-n-octylphosphine oxide (TOPO)

in cyclchexane to 3 g of Microthene or Kel-F powder. Add

30 ml of 4 M HNO, and stir for 30 min. Transfer one of the
slurries to a glgss chromatographic column.

2. Pretreatment cof samples:

a) Seg water: to 50 t, add 10 ml of a solution of S0 mg
Fe ?> ml™! in 0.5 ¥ HC1l and -1 adpm of ?*%Pu or 2?¢Pu
tracer. Stir and add 200 ml of 2 ¥ NaHSO,, follwed by
encugh conc. ammonia to give an alkaline sH. Let the
precipitate stand overnight. Siphon off the solution;
centrifuge the precipitate, and dissolve it in the minimum-
quantity of conc. HNO;. Add 100 ml of 8 M HNO, and S ml
of 30% H,0,, and heat the solution to boiling.” Dilute
to 1 % thfi 4 M HNOa, add ~-1C g Nafloz in water, and stir
for 15 min. -

b) Sediments: dry the sediment at 105°C to constant weight.
Add -2 adpm of ?*2Py or ?3°Pu tracer to 100 g of sediment
and leach by boiling with 50C =1 of 8 M HNO, for 3 h.
Filter the sclution and repeat the leaching procedure
twice more. Combine the leachings, add 25 ml of 30% Hzoz,
and evaporate the sclution tc 500 ml. Dilute to 1 2
with distilled water, and -10 g of NaNO,, and stir for
15 min. :

¢) Harine organisms: dry the sample at 1C5°C to con:tant
weight. Add -2 adpm of *“*2Pu or 2?®Pu tracer to 300 g
cf dry sample and heat in a muffle furnace at ¥50°C for
S h. Cool, add 50-100 ml of conc. HNO, and 10 ml of
30% H,0,, and dry under an infrared lamp. Heat again in
nufflz furnace at 450°C. Repeat the wet and dry mineral-
ization to give a carbon-free residue. Dissolve the '
residue in 500 ml of 8 M HNO,, boil, filter, and dilute
t0o 1 £ with water. Add 2.5 of NaNoO, and stir for 1S min.
Bokerta/Choppin/Wild
page 45

‘Add the remaining extraction slurry to the sample solution

( -% H in HNO,) and stir for 1 h, Fiiter on & Buchner funnel
and transfer i.e slurry containing the Pu(IV) quantitatively
to an empty glass chromatographic column.

Wash with 50 ml of & M HKC. and elute with 80 ml of 6 M
HC1/0.02 M HI at a flow raie of 0.25 ml min™!.

Evaporate the eluate to dryness, add a few drops of conc.
t0 rexsove iodine, and dissoclve the residue in 20 ml
£ 4 M ENC;. Stir for 15 min, add 89 mg of NaNO, in water,
and stir again for 15 minutes.

Fass the solution through the other -hromatographxc column
at 0.25 ml min~!; wash with 50 ml of & and elute the
Pu with 80 ml of 5 N NC1/0.0Z M HI. Evapora%e the eluate to

dryness.

Dissolve the residue in 0.5 ml conc. heat for 5 min.
Add 3 ml of distilled water and 2 dropg o? methyl red indi-
cator. Add conc. ammonia until the color changes to yeilow.
Quickly transfer the soluticn to a plating cell; wash the
beaker several times with a total of 5 ml of 1 vol ‘' H SO .
Neutralize again with amrmonia; when yellow color occur

add just enough HZSO to restore rec color.

Electroplate for 5 h at 60C mA; just before the end of the
plating procedure, add 1 ml of conc. ammonia to quench the
electrolysis. Wash the planchet with distilled water and
allcw to dry. Use g-Spectrometry to deternlne Pu isotopic
content and chemical vield (see Necte). .

Ncte: Average chemical yields for this procedure were:
62.6 + 9.7% for sea water samples, 45.4 + 9.6%
for sediments, and 81.7 * 4.5% for marine organisms.
Sensitivities down to 1007 fCi per kg of sea water
and 100 fCi per g of sediment can be obtained.
Roberts/Choppin/Wild
page &6

PROCEBURE u

The Determination of Plutonium in Environmental
Samples by Extraction with Tridodecylamine

Source: J. C. Veselsky, Int. J. Appl. Radiation and Isotopes

27, 439 (1976). | ‘

Sample Type: Soils

Prcoccedure:

1.

16.

Add 10 ml of water containing a suitable smount of #¥%Py
tracer to 50 g of air-dried scil in a porcelain dish. After
drying the tracer solution, ash the sample at 500°C for
several hours (or overnLght).

Boil the sample for 3 h with 200 ml of 8 M HNO, including
-1 g of NaNO,. Cocl and decant the soiuiiop 1nto a 250 ml
centrifuge giass and centrifuge for 10 min.

Transfer the nitric acid sclution toc a 500 ml separatory funnel
and extract twice (5 min each) with 40 el portions of 25%
tridodecylamine (TLA) in xjlene which has been preequxlxhr&ted
with § M HNO,.

Cozbine the corganic extracts, centrifuge for S min and discard
any agueous solution. Transfer the organic phase to a 250 ml
separatory funnel &nd wash with 25 mi of 8 M HNO, (3 min).
Discard the aqgueous phase.

Centrifuge the organic phase for S min and discard any aqueous
solution., :

Wash the organlc phase 3 times with 25 ml of 10 M HCl (3 min
each) in the separatory funnel, discarding the aqueous phase
each time.

Strip the Pu by shaking the organic phase for $S min each with
two 80 ml portions of a solution of 30 ml conc. HCl + 0.3 ml
conc. HF in 1 &£ of water. Wash the combined aqueous back-
extractants with 50 ml of xylene.

Transfer the aqueous back-extractant to a Teflor beaker and
evarcrate to dryness under a heat lamp. :

Dissolve the residue in § ml conc. HNO,, add 5 drops of
30% H,0,, and evapcrate to dryness again. :

Dissolve the residue¢ in S ml of conc. HCl, evaporate to dry-
ness, and digzolve the residue again in 5 ml of conc. HCl +
t gl of 3.2 E_EH Cl solution. Evaporate to dryness.
ll.

12.

13.

Roberts/Choppin/uWild
page &7

Dissclve the dry NH,Cl residue in 3 =l of water and transfer
to an electroplating cell. WYash the beaker with 1 al of :
water and add this to the cell. :

Add 1 drop of methyl violat indicator and electrolyze for
about 20 min at 1% V and 1.5 A. Add Z ml of conc. ammonia
solution tc the cell about 1 mir before the end of electrolysis
without interrupticn of the current. -

Ramove the planchet from the cell, wash with water and dry
under a heat lamp. Determine the Pu isotopic content and
chemical content by a-spectrometry (see Note).

Note: Chemical yields for so0il samples ranged up to 70%;
for plant ashes, > 90% ¥ie1d was obtained. Sensitiv-
ities down to C.1 pCi ???Pu per 50 g of soil can be
obtained.
Roberts/Choppin/uWild
page 48

PROCEDURE S

Solvent Extraction Method for Determination
" of Plutoniua in Soft Tissue

Source: M. P. Singh, S. A. Ibrahim, N. Cohen, and M. E.

Wrenn, Anal. Chem. 50, 357 (1978).

Sample Type: Soft Tissue

Procedure:

l.

ac 500-1000 g of tissue in a u L beaker, add 1-2 adpm
cf **2py tracer and enough conc. HNO, to just cover the
tissue. 3

Heart gently over a magnetic stirrer hot plate until frothing
ceases. Ra-se the temperature to 100°C and heat untzl the:
volume is ~100 ml.

Increase the temperature and add a ‘eu drops of conc. HNOj3
occasionally until the solution is clear

Add 200 ml of an equal-voluxe mixture of conc. HNO., and conc.
H,SO, and heat vigorously until ail the nitric acid i

dfiven off. Add a few drops of conc. HNO, occasionally with
constant heating until a clear colorless golutxon is obrained.
Remove most of the sulfuric acid by evaporation before pro-
ceeding further.

Add 3C0 ml of & M HC1l to the clear solution and boil for
sege—al minutes. Cool and add 1 ml of Fe carrier (100 =g
Fe'?); swirl the beaker for proper mixing.

Add conc. ammonia solution gently until the precipitation is
complete (pH > 8). Gently heat the precipitate with constant
stirring and allow to stand overnight. :

Separate the precipitate from the supernatant by centrifug-
ation in a 50 ml centrifuge cone. Dissolve the prec;pxtate
in a 4¥-5 ml of conc. HH°§ and repreczp;tate the iron hydrox-
ide; repeat the process Several times to ensure the complete
removal of the sulfate ions (test the supernatant for SO,
with BaCl, solution).

Dissolve the precipitate in 2 minimum volume of 8 M HNO, and
adjust the HNO, concentration to 3 M.

Heat the solution gently and add 25 mg of Nafloz. Cool the
solutrtion to room temperature.
10.

ll.
l2.

13.
1.

1§.
16.

17.
18.

19.

Roberts/Cheppin/¥ild
page 49

Add an equal volume of 25% trilaurylamine (TLA) in xylene
which has been preequilibrated with 3 M HNO, for 10 min

(Note 1). Shake gently for 10 min and eentiifuge to separate
the phases. :

Rezove the aqueous phase into another 50 ml centrifuge cone
and repeat the extraction using a fresh portion of TLA
extractant.

Combine the organic phases and wasi for 10 min with an equal
voiume of 10 M HCl. Centrifuge to separate the phasas.
Repeat this washing tc insure remcval of Th.

Wash the organic phase with 8 M HNO, to remove Fe and U.

Strip the Pu from the organic¢ phase with en equal volume of
2 M H,50,, shaking for 10 min. Remove the aqueous phase and
repeai the stripping with 2 M stou. Combine the aqueous
back--extractant solutions. :

Evaporate the solution to dryness.

For electroplating, add 1 ml of 2 M H,S0, to the beaker,
heat gently, and transfer to the eIthroacposition cell.
Repeat with two more rinses of .1 ml of 2 M H,SO,.

Acd 1 drop of methyl red indicator and titrate dropwise
with ammonia to a yellow color. KRestore the red color
with a minimum amount of 2 M H,SO,.

Electroplate at 1.2 A for 1 h. At the end of . h, just
before the current is shut off, quench the electrodeposition
by adding several drops af ammonia.

Remcve the planchet, rinse with water and alcohol, and flame
to red heat. Determine the Pu isotopic compositicn and
chemical yield by a-spectrometry (Note 2).

Note 1: The 25% solution of TLA in xylene which has been
equilibrated with 3 ¥ ENO; must be prepared fresh
each day.

Note 2: Pu recévery ranged from 48 to B85% with a mean of
61%. Sensitivities as low as a few fCi/kg tissue
can be obtained.
‘Roberts/Choppin/uWild
page 50

PROCEDURE 5

Deterzination of Plutonium in Tissue by Aliquat-336 Extraction

Source: I. M. Fisenne and F. M. Perry, Radiochem. Radicanal.

Letr 33, 259 (1978).

Sample Type: Human or animal tissue

Procedure:

1.

A weighed amount of tissue is wet-Zshed in conc. HNO,
containing a known amount of 2*2Pu tracer to achieve destruc-

"tion of the organic asterial. Evaporate the solution just

to the point of dryness.

Ad¢ 100 ml of 8.5 M HNO, to the sample and warm to 83°C
to effect coaplete dissglution. Add 25 mg of NaNGC, to
convert the Pu to the IV oxidation state. COntinuz warming
to remove excess hitrate.

Cocl the solution to room temperature. Withdraw a 100 ul
aliquot of the solution, add to 25 ml of distilled water, and
titrate to the phenolphthalein end point with 0.1 N NaCH.

If the HNO. concentration is between 8 ahd 8.7 N, proceed to
step 4. Ii not, adjust the concentration to 8.% N with
either distilled water or ccnc. HNO,, as required.

Prewash a 30 vol % Aliquat-336 in toluene solution three
tizes with equal volumes of 8.5 N HNO,. Add two 50 =l
portions of the Aliquat-336 sclution io each of two 250
ml separatory funnels. Add 300 mg of Catfloa)zdissolved in
8.5 N HKO, to the first separato-y funnel.

Transfer the sample with washes to the first separatory
funnel and shake for 3 min. Separate the phases and draw
off the aquecus phase into the second separatory funnel.

Shake the second separatory funnel for 3 min and separate
the phases. Discard the aqueocus phase.

Combine the extractant phases into a separatory funnel and
wash twice for 3 min each with equal volumes of 8.5 N

HNO. and twice for 3 min each with equal volumaes of conc. HCl.
Discard all of the acid washes.

Strip the Pu from the Aliquat-336 with two equal-volume
washes of 1 N HCL/0.01 K HF sclution. Combine the agueous
strip sclutions.
10.

ll.

" Roberts./Choppin/Wild
page 51

Evaporate the gtrip solution to near dryness; add 5 ml of
conc. EED, and 0.5 =l of conc. H,50,. Heat the solution
until denfe, white fumes appear.

Add zonc. HNO, dropwise tc the hot soluticon to remeove any
residuali orgafiic matter and cool the solution to rooa

terperature.

Transfor the sclutiorn to an electrodeposition cell which
can be 229led in an ice-water bath. Electrclyze the Pu
antd 2 ~latinue Cisk for 2 h at 1.2 A. Determine tha Pu
Ligte.. comvent and chemical yield by a-spectrometry
(gece Hore).

Note: Typicel sarples ranged from 17 to 470 g of wet tissue;
chenical yields were typically 70-80%. Activities
of ¥%?Pu down to 0.1 edpm/kg of tissue can be
cbserved.
Robercs/Choppin/uWild
page 5.

PROCEDURE 7

Determination of Trace Amounts of Plutonium
in Urine

Source: J. C. Vesalsky, Milxochim. Acta, 1978I, 79.

Samnple Type: Urine

Procedure:

1.

To the urine sample (1-1.5 L), add 200 =l of conc. HNOi
e

-1 adpz of 23€py tracer, and S ml of a calcium hespha
carrier solution (Note 1l).

Heat the solution to 80-30°C for 3 h. ?reczptafe with 500
ml of conc. an:on;a, decant the supernatant, and centr;fuge
the precipitate in a 250 ml centrifuge tube.

Dissolve the precipitate in the centrifuge tube in a minimum
volume of 3.5 M HNO; and add & ml of 30% H,0,.

Evaporate to dryness in a silicone bath. Repeat steps 3 and
4 until the salts appear white or pale yellow.

Add 0.5 g of solid NzNO, to the residue, followed by 25 =l
cf 7.2 M HNO,. Heat in"a siliccne bath until gas evolution
ceases. Cooi to room temperature,

Pass the solution through a 1 em diam. ion-exchange column
of 8 g 100-200 mesh Dowex 1-X2 resin which has been prewashed
with 7.2 M HNO,. Wash 3 times with $ ml portions of 7.2 ¥
HNO,, followed by 2 washes with S ml of 10 M HCl.

Elute the Pu (see Note 2) with 25 ml of a solution C.36
M in HCl and 0.01 M in HF into a beaker containing S ml
of conc. HNO,. Evaporate to dryness.

Add ¥ =1 of 3.2 M NH Cl solution to the resxdue. evaporate to
aryness.

Follow steps 1ll-13 of Procedure u for the preparation of an
electroplated sample suitable for a=-pulse height analysis
(Note 3).

Note 1: The calcium phosphate carrier solution is prepared
by dissolving 60 g of calcium phosphate in 150 ml
of 8 ¥ HNO; and diluting to 1 L with distilled water.

Note 2: Any Np initially present in the urine sample will be
eluted 2lso. Neptunium-237 and 2'?Py can be distin-
guished by a-spectrometry. . If & Np-Pu separation is

required, a reductive elution (using, e.g., 10 M
HClIo 2 M HI solution)} must be used.
Roberts/Choppin/Wild
page 33

Note 3: Pu racovery is usually > 30%; the detection limit
is about 40 £Ci of 2?°P4 per liter of urine.
Roberts/Choppin/VWild
page 5&

PROCEDURE 8

Extractive Photometric Determination of Plutonium{(IV)
with Aliquat-336 and Xylenol Orange?®

Source: J. P. Shukula and M. S. Subramanian, J. -Radicanel. Chenm.
47, 29 (1978).

Sample Type: Solution

Procedure:

1. Transfer an aliquot of solution corntaining ug quantities
of Pu(IV) to a centrifuge tube containing 2 ml of & M HNC,.

2. Extract twice with 2 ml portions o 5% Aliquat-336 in xylene
which has been preequilibrated with 4 M HNO,. Extraction
time should be abcat 5§ min.

3. Combine the organic extracts; transfer a 0.5 ml portion to a
10 ml volumetric flask.

u. Add to the volumetric flask 2 ml of absclute ethanol, 0.5
ml of glacial acetic acid, and 2 mi of a 0.2 w/v § solution
of xylenol qrange in methanol. Diliute to the mark with
absolute ethanol.

5. Transfer an aliquot to a spectrophotometer cell anéd read
the absorbance at 540 nm against a reagent blank prepared
in the same manner. Compute the amcunt of plutonium
extracted into the organic phase frcm a calibration curve.

Note: The extraction of Pu(IV) into Aliquat-336 in xylene
(5 w/v § solution) was found to be a maximum and
quantitative at 4 M HNC,. The extrlcted Pu complex
with xylenol orange obeyed Beer's Law ig the goncen;
tr;tion range 1-§ PP&. Ions such as Al s Cu *,

. Hoon » Ni ¢, Hn Zn » alkali and alkal;ne

earths could be tolerated in levels as ‘much as one
thgusand t;mes +greater than Pu, while ions such as
Cr °, Fe , and ¥ could be tolerated in smaller
amounts. S:gn-fxcant interferences from “a(IV) and
Cr(VI) vere obtained.

* A similar procedure from the same authcrs using di-n-hexyl sulfox-
ide instead of Aliquat-336 is detailed in T'aciochem. Radiocanal.
Lett. 37, 77 (1979).
Roberts/Choppin/Wild
page 55
PROCEDURE 9

Simultanecus Caterminations of Plutonium Alpha- and
Beta-Activity in Liquid Effluents and Environmentzl. Samples

Source: G. C. Hands and B. 0. B. Conway, Analyst 102, %3« (1977).

Sezple Type: Solutions

Frocedure:

1.

30.

1l.

12.

Transfer not more than 50 ml of the sample solution into a
125 ]l Erlenmeyer flask. Add 3 g of K SOy, ? ml of cone.
H,S0,, and 6 drops each of conc. HNO, &nd'80V HC10,.

Evaporate the mixture to fumes and fuse over a high-temperature
burner (such as 2 Meker).

Cool, add 30 ml of distilled water and 2 ml of conc. HH03;
heat to dissolve the solids.

¢ 5 ml of 1 M NaBr0., solution and Soil gently for 15 min,
xeeping the volume coflsrant by adding water as necessary.

Cool and add dropwise 2 mi of 30% H,0,, allowing the reactior
<0 proceed gently.

Boil the solution for 5 min, add 1 ml of 30% Hzoz, and boil
for 5 more min. _

Cool and add 1 ml of 10 mg/ml ng’ carrier solution. Mix
and transfer quantitatively into a centrifuge tube.

Add 50V NaOH solution until precipitation is complete.
Centrifuge; wash the precipitate twice with water. Discard
the supesrnatant and wvash solutions.

Dissolve the precipitate in 5 ml of conc. HCl. Transfer the
sclution to an ion exchange coluan approximately 14 mm in diam,
and 150 mm high containing AG 1-X2 resin which has bzen pre-
treated with 100 ml of 9 M ECl containing 1 drop of 30% H,0,.

Pass the sample through the coluen at 3 ml/min ard wash with
75 ml of 9 M HCl, discarding the eluate solution.

Elute iron with 50 ml of 7.2 M HNO and uranium with 10C ml
more of 7.2 M HNO,. Discard 'hese eluates.

Wash the nitric acid from the column with 10 ml cf 1.2 M ECI
and elute Pu with & freshly prepared solution of 50 ml of
1.2 ¥ HC1 and 1 ml of 30% H,0, at 3 ml/min.
13-

1ls.

15.

16.

Roberts/Choppin/uild
page 56

Transfer the eluate to a centrifuge bottle and add 1 ml
of the Mg carrier solution. Precipitate by the dropuise
addition of S0% NaOH solution. Centrifuge and wash twice
with water, discarding the supernatant and wash solutions.

Dissolve the precipitate and wash the solutiorn into a
separatory funnel, using a total of 10 ml of 2 g.unos.
Add 5§ ml of a 25 vol. percent solution of HDEHP in n=
heptane and extract for § ain.

Discard the aquecus phase and transfer the organic layer into
a2 glass scintillation counting vial. Add 10 ml of scintillant
(Note 1), mix, and count in a three-channel liquid-scintill-
atior spectromster. Use two channels which have been
previously optimized for counting a and B8 activity.

Calculate the #*!'Pu activity in pCi/f from the equation
(c~b) x 1000

Iv1py activity =
2.22 x Ex V
where ¢ is the sample count rate, b is the background count
rate, E is the counting efficiency for 2“'Pu and V is the
volume of the sample aliquot in mi. Calculate the Pu c
activity similarly, using the counts recorded in the a-counting
channel (Note 2).

Note 1l: For the scintillartor solutien, dissolve 4.64 g of
p-terphenyl and 0.115 g of 2-(S-phenyl-oxazolyl)-
benzene (POPOP) in 1 L of scintillator-grade toluene.

Note 2: Awerag- recovery is 94.0 + 1.8V for *°*'Pu_and 97.6
+ 3.8% for *?"Py. Limitsof 1.7 pCi for **'Pu and
U.2u pCi for ~21??Pu can be achieved, depending on
counter. backgrounds.
Roberts/Choppin/tild
page 37

V1i. Onidatien Stace Procedures

INTRODUCTION

Thorium exists in oxidation 1V and the transplutonium
actinides are typically trivalent although some use is made of
other oxidation states in their separation schemes. Uranium is
most comweonly found a&s U(VI) in the form of the divalent U0 .
However, neptunium and plutonium exist rather readily in oxgdation
states III, IV, V and VI. Since the behavior in nature of these
latter two elemerts is dependent on the oxidaticn state or states
present in a particu.ear scil or water, a major problem has been
the separation of the neptunium and plutonium 3zpecies present
in a sample without changing the redox equilibria. The next
three procedures are schemes for such separations. :

In the first procedure, a combination of selective sorption
and solvert extraction is used to separate Np(IV), Np(V) and
Np(YiI}). The same procedure works for plutonium. The second
procedure uses solvent extraction by TTA with aqueous solutions
of different pH values to achieve separation of the IV, V and
VI states. Since many nagtural waters are about neutral, a similar
procedure has been developed using dibenzoylmethane (DBM) which
1s less scluble in neutral aqueous solutions than is TTA. This
is described in Procedure 3 for oxidation states III, IV, V and V¥I.
The An(IV) is sorbed on the vessel walls in the first extraction
but is pla ed in sclution by the dilute HCl and extracted sub-
sequently.
hobercs/Choppin/uild
page 58

- PROCEDURE 1

Separation of Kp(IV), Np(V) and Np(VI) by
Adsorption and Extraction

Source: Y. Inone and 0. Tochiyama, J. Inorg. Nucl. Chem.,

39, 1uu3 (1977).

Sample Type: Solutions

Procedure:

1.

(a)
(b)

Adjust an aliquot of the Np solution to pH6é with acetic acid
and/or ammoniuz hydroxide at a total volume of 5 ml. Add 100
mg silicic acid powder (100 mesh). Shake occasionally for

30 nig. iThe Np(IV) and Np(VI) are 100% sorbed, leaving Kp(V)
in solution.

After separation by centrifugation, adjust the pH to 10-ll and
add a fresh 100 mg sample of silicic acid. With 30 minutes
occasional shaking, the Np(V) sorbs coapletely.

To a fresh aliquot of the Np solutxon. add HC10, to cktain 5 ml
solution which is 1M in RC10,

Prepare a frtsh precipate of BaSO, by mixing 1 ml each of

.1 M Ba(NO and 0.2 M Na,SO, After 30 min, remove the
supernate afid add the Np so utxon. Allow 310 min for cocmplete
sorption of the Np(IV) with no sorption of Kp(V) or Np(VI).

Cxidation state differentiation can alsoc be achieved with
40% (v/v) TBP in benzene. From 3 M HCl solution, after 5-10
min, 90V extraction of Np(VI) is obtained with <5% Np(IV)

and Np(V). From 6 M HCi solutlon, after 5-1C min, 80% Np(IV)
and 100% Np(VI) but no Np(V) is extracted.

Note: This method has >=en used Zor pluteonium also.
Pu(¥) sorbs on CaC0, (ref. a) and TiO, (ref. D) and can be
separated from Pu(Ui) by a modificatidén of the above procedure
since Pu(IV) sorbs at lower pH values.

REFERENCES

E. A. Bondietti and J. K. Trabalka, Radiochem. Radicanal.
Chem. Lett., 42, 169 (1979).
Roberts/Choppin/uilid
page 59

PROCEDURE 2

Separation of Oxidation Stat=s IV, V and VI
by Solvent Extraction

Source: P. A. Bertrand, G. R. Choppin, Radiochim. Acta,

31, 135 (1982).

Sample Type: Solution

Procedure:

1.

2.

A 0.5 ml aliquot of the actinide solution is added to 0.5 ml
of 0.5 M acid (HC10,, HCl, HNO,> to obtain a pH ca. 0.6.

This solution (1 ml) is mixed with 1 ml of 0.5 M TTA solution
in xylene or toluene and the mixture shaken vigorously for

S min. .

The phases are separated for counting; the An(IV)+ is

%1008 extracted into the TTA soluticn while the An(VI) remain
quantitatively (>98%) in the aqueous phase (Note 1).

A second (0.5 ml of the original actinide solution is added
to 0.5 ml of 0.5 M sodium acetate at pH 4.

This solution iy added to 1l ml of the 0.5 H TTA solution and
shaken for S min.

The phases are separated for counting with essentially 100%
of the An(IYV) and An(VI) in the organzc phase and 190% of
the An(Y) in the aguecus (Note 2).

+ An T actinide element

Note 1. An(IIl) would remain quantitatively in the
aqueous phase.

Note 2. An{(III) would be extracted into the organic phase.
Roberts/Choppin/Wild
page 60

PROCEDURE 3
Separation of Different Oxidation States by

Solvent Extraction in Neutral Solutions

Source: A. Saito and G. R. Choppin, Anal. Chem., 55, 2u54 (1983).
Sample Type: Neutral solutions |

Procedure: See flowsheeat
FLOWSHETT

ample solution (pH-8)
2 mab
-YT)

a) add 10 me 3.5 M DBM®
b) shake for 19 m.

prem ]
4) add S mf 0.01 M

 

 

 

 

 

 

 

a) add dilute HCl1l vo
acetate solution lower pH to -4-5,
pH 5-5.5 b) add S mt 0.2 M DBM
b) shake for 2 m. solution
c) shake for i0 n.
|

 

 

prganic phase| Bqueocus phase] prganic phase| hqueous phase|

An(VI) AnCIII) An(IV) | An(V)

#*Chloroform was used as a solvent to allow easy removal of the
_organic phase.
Procadures:

Separation of Bp(IV), NpiV) and Np(VI) by

Adsorption and Extraction.............crcccnnccnanannsnann 58
llopu:u:i.on of Oxidation Stlul- 'N V., and Vi by

Solwvent Extraction...........c.iiir tiiiiiinicrrrrrenannas 59
Separation of Diffierent Oxidation States by

Solvent Extraction im Beutral Solutionms................ . ..60

vii