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National
Academy
of
Sciences
vNational Research Council
I
NUCLEAR SCIENCE SERIES
The Radiochemistry
of Gold
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COMMITTEE ON NUCLEAR SCIENCE
L. F. CURTISS, Chairman ROBLEY D. EVANS, Vice Ch airm a nNationalureauofStandards Massachusettsnstitute fTechnology
J.A. DeJUREN, SecretaryWestinghouseElectr icorpora tion
C. J.BORKOWSKI J.W. IRVINE,JR.Oak RidgeNationalLabora tory Massachusett snstitutefTechnology
ROBERT G. COCHRANTexas AgriculturalndMechanical
College
SAMUEL EPSTEINCalifornianstitu te fTechnology
U. FANONationalureauofStandards
HERBERT GOLDSTEINNuclearDevelopmentCorpora tionf
America
E. D. KLEMANorthwesternUniversity
W. WAYNE MEINKEUniversityfMichigan
J.J.NICKSONMemorialHospital,ew York
ROBERT L.PLATZMANLaboratoiree ChimiePhysique
D. M. VAN PATTERBartolResearchFoundation
LIAISON MEMBERS
PAUL C.AEBERSOLD CHARLES K. REEDAtomicEnergyCommission U. S.Air Force
J .HOWARD McMILLEN WILLIAM E.WRIGHTNationalc ienceFoundation OfficeofNavalResearch
SUBCOMMITTEE ON RADIOCHEMISTRY
W. WAYNE ME INKE, Chairman HAROLD KIRBYUniversityfMichigan Mound Laboratory
GREGORY R.CHOPPIN GEORGE LEDDICOTTEFloridaStateUniversity Oak RidgeNationalaboratory
GEORGE A. COWANLos Alamos Scientific aboratory
ARTHUR W. FAIRHALLlJniversity fWashington
JEROME HUDISBrookhavenNationalaboratory
EARL HYDEUniversityfCaliforn iaBerkeley)
JULfAN NIELSENHanfordLaboratories
ELLIS P. STEINBERGArgonneNationalaboratory
PETER C. STEVENSONUniversityfCal iforniaLivermore)
LEO YAFFEMcGillUniversity
CONSULTANTS
NATHAN BALLOU JAMES DeVOE
NavalRadiologicalefenseLaboratory UniversityfMichiganWILLIAM MARLOWNationalureauofStandards
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CHEMLSTRY
The Radiochemistry bf Gold
J. F. EMERY and G. W. LEDDICOTTE
Oa k Rid ge Na tion al La bora toryOa k Rid ge , Te nn es se e
Issuance ateMay1961
Subcommittee on RadioChemistry
NationalAcademy ofSciences Nat ional Research Council
PrintednUSA. Price$0.50.AvailableromtbeOfficefTecbnicnlServices,eprtmentofCommerce,Wne.blngton 5,D. C.
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FOREWORD
The Subcommittee on Radiochemistry is one of a number ofsubcommittees working under the Committee on Nuclear Sciencewithin the National Academy of Sciences - National ResearchCouncil. Its members represent government, industrial, anduniversity laboratories in the areas of nuclear chemistry andanalytical chemistry,
The Subcommitteenuclear science whichtion and distribution
has concerned itself with those areas ofinvolve the chemist, such as the collec-of radiochemical procedures, the estab-
lishment of specifications for radiochemically pure reagenks,availability of cyclotron time for service irradiations, theplace of radiochemistry in the undergraduate college program,etc.
This series of monographs has grown out of the need forup-to-date compilations of radiochemical information and pro-cedures. The Subcommittee has endeavored to present a serieswhich will be of maximum use to the working scientist andwhich contains the latest available information. Each mono-.ma~h collects in one volume the wertinent information reauired~or-radiocbemical work with an individual element or aclosely related elements.
.Anexpert in the radiochemistry of the particularhas written the monograph, following a standard formatby the Subcommittee. The Atomic Energy Commission hasthe printing of the series.
grotip of
elementdevelopedsponsored
The Subcommittee is confident these publications will beuseful.not only to the radiochemist but also to the researchworker in other fields such as physics, biochemistry or medicinewho wishes to use radiochemical techniques Gosolve a specificproblem.
W. Wasme Meinke, ChairmanSubcobittee on-Radiochemistry
iii
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INTRODUCTION
This volume which deals with the.,radlochemistry of gold1s one of a series of monographs on radiochemlstry of theelements. There Is included a review of the nuclear andchemical features of particular interest to the radiochemist,a discussion of problems of dissolution of a sample andcounting techniques, and finally, a collection of radlochemlcalprocedures for the element as found In the literature.
The series of monographs will cover all elements forwhich radiochemical procedures are pertinent. Plans Includerevision of the monograph periodically as new techniques andprocedures warrant. The reader Is therefore encouraged tocall to the attention of the author any published or unpublishedmaterial on the radlochemistry of gold which might be IncludedIn a revised version of the monograph.
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CONTENTS
3.. GeneralReferenceso= Vne Inorganicand.Analytical Chemistry of Gold . . . . . . . .
11. Radioactive Nuclides ofGold . . . . . . . .
III. The Cnemistryof Goldand ItsApplicationtothe Radiochemistryf Gold.Radionuclides .
A. Reviewof the Chemistryof Gold . . . .1. MetallicGold . . . . . . . . . . .2. The Compoundsof Gold . . . . . . .
s,. The Oxideand OxyacidCom~oundsof Gold . . . . . . . . . . . .
b. The Halide Compounds of Gold . .c. The Sulfide Compounds of Go3.d .d. The Cyanide and.Cyanoaurate
Compounds of Gold . . . . . . .e. The Organometallic Compounds of
Gold. . . . . . . . . . . . .
B. Analytical Methods for Gold . . . . .1. Separation by Reduction to Metal .2. Volatilization . . . . . . . . . .
3 . Separation by Electrolytic Methods4. Separ:%tionby Solvent Extraction .
a. Ion Association Systems . . .b. Chelate Complex Systems . . .
5. Separati ons by Ion Exch w w Res in s
.
.
.
.
.
.
6. Se~arations b; PaperChrornatowaPhYand Electrophores~s . . . . . . . .
IV. Decomposition of Materiak Containing Gold .
v. SSfety Practices .. . . . . . . . . . . . . .
. . . . . .
. . . . . .
. . . . . .
. . . . . .
. . . . .
. . . . . .
. . . . . .
. . . . . .
. . . . . .
. . . . . ..
. . . . . .
. . . . . .
. . . . . .
. . . . . .
. . . . . .
. . . . . .
. . . . . .
. . . . . .
. . . . . .
. . . . . .
. . . . . .
VI. Counting Techniques for Radioactive Gold Isotopes . . .
VII . Collection of Detailed Radiochemical Proceduresfor GOld. . . . . . . . . . . . . . . . . . . . . . . .
References . . . . . . . . . . . . . . . . . . . . . . . . . . .
Appendix A . . . . . . . . . . . . . . . . . . . . . . . . . ,
1
1
~
1+
56
67
10
11
12
1212131313141515
16
17
17
17
18
31
34
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The Rad ioc hem is t ry of Gold
J. F. EMERY and G. W. LEDDICOTTE
Oa k R id ge Na tion ul La bora tory *Oa k Rid ge , Ten nes s ee
I. GENERALREFERENCESON THE INORGANICAND AIJALYTICALCHEMISTRYOF GOLD
1.
2.
3 .
4 .
5 .
6 .
7 .
8 .
Kleinberg,J., Argersinger,W. J., Jr., and Griswold, E., Inor-ganic Chemistry, p. 589-606, Heath, Boston (1960).
Sidgwick, N . V., The Chemical Elements and Their Compounds,p. 103-92, Oxford UniversityPress, Iondon (1950).
Sneed, M. C., Maynard, J. L., and Brasted, R. C., ComprehensiveInorganic Chemist ry, Vo lume II, Van Nos trand , New York (1954).
Remy, H., Treat ise on Inorganic Chemist ry , vol. I, p. h9-422,FAsevier, Amsterdam (1956).
Latimer, W. M., The Oxidation States of the Elements and TheirPotentials in Aqueous Solut ions, 2nd Edition, Prent ice-Hall ,Inc., NewYork (1952).
Chariot , G. and Bezier, D., Quant itat ive Inorganic Analysis,JohnWiley and Sons, Inc., New York (1957).
Hillebrand, W. F., Lundell, G. E. F., Bright, H. A. and Hoffman,J. I., Appli ed Inorgan ic Analysisj John Wiley and Sons, Inc.,New York, 1953.
Treadwell, F. P, and Hall, W. T., Analytical Chemistry, Vol. II,John Wiley and Sons, Inc., New York, 19k2.
IT. RADIOACTIVE NUCLIDES OF GOLD
The radioactive nuclides of gold that are of interest in the radio-
chemistry of gold are given in Table I. This table has been compiled from
*Operated for U. S . Atomic Energy Conmrissionby Union Carbide Nuc learCompany.
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informationappe~ in reportsby Stromi~r, etal., (l-) and by Hughee
Table 1. ~OaCtive hC~deE Of Oold
Radio-nucllde.e
~191
~lg2
~u193m
~193
hw
~ulg%
~~95
*ulgiul
#6
~uwb
*ulg8
@9
Au~
@l
@2
&03
Half-1ife
3.0 h
4,7 h
3.8 e
16h
39.5 n
30s
U35 d
14.0 h
5.60 a
7 .L B
2.70 d
3.15 d
Mm
26 m
25 EI
55 B
Mode ofDecay Ener#ee ti R41atlon
m 7: 0.3;0.1L; O .60
-EC,p --:--73 l~7# .*
IT- j: 0.257 ;0.0*-
EC 7: 0.112;0.i73;0.l&j
EC, p 7: 0.327 ;0.291;0.611
IT 7: o.261;o.om;o.318
N 7: o.031;o.ogg;o.130
EC orIT
m, B- 13-0.307: o.331;o.35L
m 7: o.130;o.m;o.44J7
P- 13- 0.959; 0.28;1.377: o.u77;o.676;lmo8g
P- 13- 0.30; 0.25;0.467: 0.209 ;0.050
P- p- 2.27: 1.13;0.39
r p- 1.57: 0.55
if B-.1.9
ProducedBy
Ir(a#n)~igi
Pt(d,3n)AU191
Ir(a,3U)q1&Pt(d,2n)&l
Ir(q2n)fu&3Pt(d,n)Au
W(d,3n)Au193
Ir(a,3n)Au~~~
1pt(wn AU@
7t[:n7i3*
2
.
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III. TEE CHEMI~OF GOLD ANOGOLD RADIONUCLIDES
Radiochemlstryie probably
nique used primarily either (1)
ITS APPLICATIONTO THE RADIOCHR41SFRY OF
best desctibedas being au analysietech-
to assist in obtaininga pure radionuc~de
in some fomn BO that au *solute measurementof its rsdioactivlty,radia-
tion ener@es and hal f- li fe can be mede, or (2) to determine the amount
of radioactivity of a particularrailioelenentn a radionucliderdxture,
or (3) to completea radioac tiva tlonmlysis being used to detemine the
concentmtion of a specificstable element in a particularsample material.
In order to.be an ald in accomplishingw one of the above interests,
radiochemistryusually considersthe isolationof the desired radlonuclide
by either carrier or carrier-freereparationmethods.
Generally,carriermethods are used most frequentlyin rsdiochemlstry.
&ey involve the eddltion o f a small mount of tiactive stab le element to
a solutiono f the irtiiated ma terial to serve as a carrier of the rsdlo -
nuclide of that element through the sepa=tion method. In carrier-free
separations,I.e., those rsdiochemlcaltechniquesused umstly for absolute
radioactivitymeasurements, it is requiredthat the raclloelemente iso-
lated in a manner capable o f giving either no amount or a minimal amount
of stable elemnt in the final form to be ueed in the rad i.wctlvity
measurements.
In most instances,emalyticalmillochemistryts dependentupon more
conventionalidea6 in analyticalchemistryinvolvlngseparationsby such
methods as precipitation,solvent extraction,ch&nato~aphy, volatiliza-
tion, and/or electromalysis and the subsequentpresentitlonof the isolated
radloelementIn a fomn suitablefor a measurementof the radloelementis
radioactivity. One major differenceexists between carrier rsdlochemistry
and more convent ionaltechniquesIn tha t i t i s not a lways necessq to
recover ccnnpletelyhe added amunt of carrier element,since a radl.o-
chemicalanalysis is designed to assure thalithe
element achieve an Isotopicstate with the atoms
atoms of a radioac tive
of the inactiveelement
3
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end my loss of the radioac tivespecies i s propor tiona lto the loss of
carrier d- the separationprocess.
Calorimetric,Plaro-phic snd slmllar analysistechniquesare sel-
dom used In ~ochemlstry because they do not se~te the desired radlo-
twsi.mmts (either radioactiveor stable) in the mixtureucllde from con
being analyzed. However, some of the developmentsused in these analysls
techniquesmaybe useful in radiochedstry. Appen djx A Jlsts some of the
more recent referencescited for the detmmlnat ion of gold by such analys is
techniques.
The @heral Informationthat follows describesthe behavior of gold
and Its compoundsW how this behavior canbe used in developing radio-
chmaical analysismethods for the gold radlonuclides. More detailed infor-
mation can be obtained either from the specificreferencesgiven In this
sect ionor f rom the ~nera l referencesgiven in Sect IonI of this monograph.
A. Review of the Chemist~ of Gold
Gold is generallyfound in the nat ive fomi as very f ine meta lllcpar-
ticles dispersedthrough quartz. I t is also found associatedulth sul-
fide ores such as pyrite, chalcopyrite, e.rseno~ ite, and stlbnite. Gold
also appears as finely dispersedparticlesh tellurldeore compounds,
euch as ~te (a mixkre of lead, gold, copper and silver suU?ides
and tellulldes),calaverite,AuTe2, sylvanlte,AgAu1e4,and in SOIE com-
ds and ores are found as originalounds of selenlum. Most of these compoun
ore deposi ts . In some ins tances, i t i s poss ib le to obtain gold in i ts
native state from secondary,or sJluvial,depxits. Here the gold, m
the free metal or as a gold-containingcompound,has been removed from
the place of originaldeposit ,byerosion and laid down agtin in a secondary
deposi t,where i t i s usual ly found in the fozmof fine or very f ine grains .
Gold can be recovered from the sedimentsobtainedby washing these
depsits . The washing technique IS often cmibinedwith an amalgamation
process in which the gold in a sedhwnt Is dissolved In mercury to form
4
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an amalgam. The gold is recoveredfrcnnthe amalgamby distillingoff
the mercury, The most Impotin t process for ex trac tinggold fmm its ores
is the cyanide process. Here the finely -d ore is leached ulth pota,e-
siwn or sodium cyanide solution. The gold is converted to a solublecom-
plex cyanide and is recoveredfrom the solutlonettherby a reductionto
the
1.
metal with zinc or by electrolysis.
Metallic Gold
Metallic gold is yellow In color aud has abtight luster. It is
stable U air and is very ductile. I t cryswl. izes from solutionin the
cubic system,andit till fonz tied crystalswith platlnum,palladium,
silverW copper. I t can unite with hydrogento fonz a colorless,solid,
uns tablehydr ide,but It t il l no t reac t in ai r or with water. I t wil l
no t reac t with the halogens in the @, gaseous s ta te ;a t ordinary temp-
eratures,no direct reactionsoccur with the halogena, and it is only
possiblefor gold to combinewith fluorineat temperaturesabove 300.
However,gold till dissolvevery rapidly in an
at ordinarytemperaturesto fomn ccszplexions,
and trichlorooxoaumte ions.
Cold will diseolvein aqua regla and also
acid if strongoxidizingagents, such as icdlc
gemese dioxide,or selenlc acid, are present.
aqueous solutionof chlorine
e.g., tetrachloroaurate
in concentratedsdfuzic
acid, nitric acid, mem-
It t il l not react directly
with molten caustic alkalis or tith sulfuric,I@cOcbloric, phosphoric
or arsenic acids. I t stemda ferbelowbydrogen in the electrochemical
series; therefore, it is not able to go tito solutionby hydrogendis-
placement,andit cannotbe solubilizedeven under the oxidizingaction
of alaqpheric oxygen\3) By reason of its electrochemicalbehavior, gold
can be disp~ced frcm its solutionsby almost all other meLslE unless i t
Is in solution i n the form of a very s-ble complax.
+2 & -1Ions, such as Fe , Sn , S03-2, N02 , fi, - w, can reduce
gold and preCi~ibti
such as oxalic acid,
it from a chloride solution. organic Compouude,
formaldehyde,sugar, and tartaric, citric and acetic
5
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acids and their salts ,will also reduce gold
solutionas the metal. Acetylene and CO can
gold from chloride solutions.
2. The Compounds of Gold
Gold (like copper and silver) cm exist
and precipitateit from a
also be used to precipitate
in i ts compounds in the
valence states of +1 and +3. Although copper and silver al$o exhibit
+2oxidationstate of +2, no positive evidenceexists for Au compounds
m.
since
it a~ems that Buch compoundsas AuC~, AuO, AuS04 are compounded from
+1the conibinationf Au and AU+3 salts.4) Gold is most stable in the
+3+3 sta te gnd sal ts derived from Au are usually complex anionic salts.
+1Monwalent gold, Au , also forms complex anion salt~. Oold sulfide,
Au#, +1and the halides,AuX, are importantAu compounds. The apparent
solubilities(5)of these and other compoundsof gold are tabulatedin
Table II.
All gold congmundsare characterizedby their tendencyto decompose
easily. Reducing agents, frequentlyat only mcderate temperatures, will
cause them to dissociateand release free gold.
a. The Oxide and Oxyacid Compoundsof Oold
The existenceof a monovalentgold oxide, A~O, or a hydroxide com-
pound appears to be doubtful, (6) since the productsof a chemicalreac-
tion ~eteen ~ Au+l compoundand an alkali results in the formationof
a mixt~ of metallic gold and gold oxide, A~03. The chief methcxiof
preparing trivalentA~03 is by treatingAuC13 with qlXali or alkaline
earth hydroxides,or by boiling AuC1 with alkali carbonatesto obtain3
hydrous gold(III)oxide, AuO{OH), aud then dehydratingthis compoundat
a temperatureof 1~-150. If heatedbeyond 160, the freshly prepsred
AU203 til l begin losing oxygen. The hydrous gold oxide, or auric acid,
is smphotericand is soluble in concentratedhydrochloric,nitric and
suituricacids forming complex oxyacid solutioncompmmda, such as
H(AuC14), H[m(~3)4], or H[Au(S04)2]. When these solutionsare diluted,
hydrolysisoccurs and auric acid is reprecipitated. 4) If the chloride
6
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and nitrate solutions are evaporated,crystallinehydrates of these acid
solutionscan be obtained. When am elementalsalt compoundIs added to
these oxyacid solutionsand the titure evaporated,solid conpundE$such as
K(AuClk), or K[Au(S04)2],?.reproduced.
Auric acid is the acid anhydrideof a seriesof compeundsknown as
the aurate salts. The evaporationof AuO{OH) h concentratedHN03 and
in the presenceof alkalihydroxidestill produce such aurate salts a~
KAu$3H20 or NsAu02.H20. Acetatoauratescam be producedby treating the
correspondingaurate, 14(Au02),with glacial acetic acid. Sulfatoaurate
salts, e.g., potassiumdisulfatoaurate(III), AU(W4)2, can alao be pro-
duced by dissolvhg AuO(OH) h concentratedsu~uric acid and adding to
the mixture a solutionof the hydrogen sfiate compoundof the element
of interestand evaporatingthe solution
200. Alkali thiosulfatecompoundswhen
will produce tkl.oaulfatoaurate(I)alte.
b. The Halide Compoumdsof Gold
to dryness
added to a
at a temperatureof
solution of AuO(OH)
Au+l can form sjmple halide compounds. Solid ~old chlotide,AuCl,
and goldbromide, AuBr, are formedby heathg (at 185) anhydrousAuC13
and AuBr~, respectively. Gold iodide, ALU, is formedby either dissolv-
3 salt solu-ng A~03 in hydriodic acid, or by adding iodide tons to Au
tions.
AuC1 Is usually obtainedas an impurepale yellow powder that will
decomposeh water to formAuC13 and elementalgold. When heated, AuC1
decomposesto prciluceelementalgold and C%. It will dissolvein alkali
chloridesolutions,to fonu complex ions, i.e., chloroaurateI ions,
(AuC12)-. AuC1 will also form complex ccmrpoundsith aumonla and can
be combinedwith carbonmonoxide to form gold carbonyl chloride,Au(CO)Cl.
All of these complex compm.mdsdecomposein aqueous solutionseither to
deposit elementalgold or to form other complex gold ions.
AuBr, is much more easily decmsed than AuC1. It dissolvesIn
alkalibromide solutionto,form bronmaurate(I)ions, (AuBr2)-. Gold
7
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TableII. Volubilityf GoldCompounds
Compounds
Bromides
Chlorides
Cyani&es
Iodides
lJitrate
Oxides
Ffiosphide
Formula
AuBr
AuBr3
AuC1
AuC13
AuCN
AU(CN)33H20
AuI
AuI3
AuH(No3)k3H20
AU20
AU20X:120
203
203kq20
U2P3
Water VolubilityCold Hot
Insoluble
Slightlysoluble
Decomposesveryslightly
Very soluble
Very slightlysoluble
Very soluble
Very slightlysoluble
Insoluble
Soluble decomposes
Insoluble
Soluble
Insoluble
Insoluble
Insoluble
Decomposes
Very soluble
Decomposes verysoluble
Slightly solubleDecomposes
Decomposes
Insoluble
Insoluble
Other Solvents
Decomposesin acid
Solublein ether
Soluble in HC1 and HBr
Soluble in a lcohol andether. Slightly solublein NH
3Insoluble in CS2
Sol ub le i n KCN and NH40H .Insoluble in a lcohol andether
Solublein alcohol andether
Sol ub le i n KI
Soluble in iodides
Soluble in HNO3
Soluble in EC1. Slightlysolhble in KOH. In solublsi n H2S04 , HN03 and a lcohol
Soluble decomposes inalkali
Soluble in HC1
Solub le i n HC1 , NaCN andCone. HNO
3I nsol ub le i n HC1 andciiluteHNO
3
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Selenlde Au,# ~
Su3fides Q2sInsoluble;fresh Precipitate InsolubleIn acid.solution colloidal Solublein KCN and aqus
re@13
%s3 Insoluble Solublein W.2S. Insolublein acid snd ether
Telluride %Te AuTe2 Insoluble Insohible
M A1.kyls *WInsoluble Insoluble Solublein benzeneand
CHcl3
%mm .molubleInsoluble Solublein benzeneand
CHcl=
(R&II)2904 Insoluble Insoluble t il&e in e ther,benze=CHC13
.n
*X = Cl, Br, I .
% . Methyl,ethyl,n-pmpyl, ISO-PrOPYl,n-bu~l) iso-bu~l> iSO-Wl> benzyl, C6H5CH2~, (%)5
Snd (CH2)1O.
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pcmition of AuSJ apparentlya double compmmd of
saturationof a hot AuC1 Bolutionwith hydrogen 3
Au# sad Au#3.
sulfide results
The
only in
the depositionof metallic gold. Gold sulfide is insolublein water and
dilute acids and forma colloidaldispersionsin the presenceof H2S. It
can be decomposedand dissolvedby strong oxidizingagents, e.g., aqua
regla and chlorine. It forms cyanoaurate(~)compoundswhen dissolved in
alkali cyanide solutions,ar@when dissolvedin alkali sulfide solutions,
it till form either thioaurateI , monothioaurate,M(AuS), or dithioaurate,
M:1(AuS2), salts. .All-ofthe gold sulfide compoundswhen treated with
excess alXali sulfide solutionswill @ve up sulfurto form polysu~ides.
Gold(I) stiide can be reprecipitatedif the thioauratecompoundsare
decompsed by acids .
Gold(III)stiide, AU.$3, caunotbe formedby a direct conibination
of the e lements. I t i s obtainedby saturat inga di lu te solutionof e ither
chloroauricacid, H(AuClk),or gold chloride,AuC13, or by,treating a dry
sl l!al isal t l ike Icl (AuC14),i th H2S. Au#3 is produced as a black powder
and will decompse at tempemituresabove 200 into the elementalconsti-
tuents. Thioaurate(III)compoundscanbe fomnedby treatingAu#3wlth
cold solutionsof alkali,suMide; however, they decomposerapidly to
form the correspondingthioaurate(I)compounds.
d. The Cysnide and Cyanoaura teC OIUPOundSOf Gold
Gold(I) cyanide,AuCN, is prcducedby evaporatinga KCN-AUC13.SOlU-
tion to form a colorlesscompound,potassium tetracyanoa&ate(III),which
when heated to temperaturesabove 200 loses cyanogento yield ~tassium
dicyanoaurate(I) , KAu(CN)2. The complexKAu(CN)2 compoundcan be decom-
posedin warm (~) hydrochloric acid to produce AuCN, KC1 and HCN. Gold
cy=ide is insoluble in water, tilute acide and hydrogen sulfide solu-
tions; however, It will dissolvein other alkali cyanides (to form other
cyauosurateI salts), sodium thiosulfate,
solutions.
No true C~pOulldOf gold(III) cyanide
11
.snmmniumsulfide and amconia
exis ts . KCN will not produce
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it by action upon a AuC1 solution,3
but til l produce gotassium tetra-
Cyanoaurate(III which when treated with strong acids and subsequent
evaporationtith H2S04 will form the trihydrateOf gold(III)mde~
Au(CN)3.~0. Potessium tetracyenoauratewill di6eolve.inalkali cyanides
, to form cyan oaurate(I)salts and in alkali sulfidesto produce mmothio-
aurates,M(AuS) md dithioaurate.s,3(AuS2). The thioauratescanbe
decomposedby acids to reproduceAL-#.
e. The OrgamometallicCompoun ds Of Gold
Gold(I) can form unstable al.@l compoundsby the action of Grignti
reagent on AuCl-CO. Trivalent gold organome te.lliccompoundsare more
sl%ble than the umivalent gold compoundsand several series of organo-
gold(III)derivativesare known, e.g., trialkyl,R U, and dialkyl goldP
ha~des, R,_&X. Anhydrous gold(III)can react directly tith arumatic
hydrocarbonsto produce a series ofmonoaryl gold(III)c_unds. Addi-
tional informationon the formation of gold organometsJMc compmrds has
been given by Remy.(4)
B. Anal@ ical Methods for Gold
As ~tited out elsewhere in this monograph, the use of a known emm-mt
of inact ivegold c tier in a separa tionmethod almost a lwaysmakes i t
pmctical to obtain the gold carrier in a weighable form in the final
step of separationprocedureused. !lhmthings are achievedif this is
done. The rsdionuclldeis concentratedtito a small mass for the radio-
activitymeasuremants, end the csrrier is obtained in a grawimetricform
which can be used to determineany loss of the car rier dur ingthe analysis.
Gold is always separatedand determinedh its ores by the fire
aasay method>)
1. Sep-tionby Reduction to Metal
Gold in solution can be separatedby reducingit to the metal with
such reducing agents aa ferrous sulfate, sulfm.dioxide, oxalic acid,
hydroquinone,magnesium and zinc. Sometimes
compoundsmix with the precipitated?netalHc
12
metal reductantsand their
gold. Sulfur dioxide also
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partiallypreclpitatkssome of the Group VIII elements, end a reduction
~th ox~ic acid is very S1OW. Hydroquinoneis cons~deredto be the
best reducinga~ent for gold; i t gives a Bharp Reparationof gold from
coppr, nickel, and zinc.(8)
Gold, occurringh the form of tel lurides,
my also be sepamted by hydroquinone. (9) Gold cynide solutionscan be
precipitatedm colloidalgoldby sdding Eulfuricacid and heating. (lo)
The sddit ionof a tmce of si lver to the ndxture assLst8 in coagula ting
the colloidalgold.
2. Volatllizatlon
Hillebrand,et al.,(11)
repart that gold is lost by volatilization
if aqua-regiasolutionsare rapidlyevaporatedto dryness or if sulfuric
acid IS dded to such solutionsand evaporateduntil H2S04 fumes appe=.
For example,solutionscontaining0.1 gm gold
tion. However, volatilizationdoes not occur
used in the eva~ration process.
3 . Separationby ElectrolyticMethods
Gold maybe electtieposited fram alkali
lost about 1-3X upon evapora-
3f 70$perchloric acid is
cyanidesInnilligram qpan:
titles. (12) sand@) reports satisfactorydewsition of gold frcnnchlo-
ride, cyanide, and thioauratesolutionsusing currentdensitiesof 2 to
3 amperes. Perkin and Pebble suggeststhe use of a dilute solution
of potassium cyanide,to which some hydrogenperoxidehas been added,
to remove gold depositedon a platinma cathode.
4. Separationby SolventExtraction
Solvent extractionmethods used ai3separationmethods for other
emelysis techniquescan often be ed.aptedfor use in radiochemistry~d
can be quite useful in separatinga radloelementeither in a cezrier
free state or in combinationwith milligram eamunts of carrier. Morri-
son and Freiser(15)
have recently reviewedthe applicationsof ion asso-
ciationand chelate complex systems to the determinationof mst of the
elements. Some of theqe methods,particul=ly those concernedwith
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organic soluble cospmuds, are applicablefor use as separationpro-
cesses in the radiochemistryof gold.
a. Ion AssociationSy stems
Le*er(6) +3has extmcted Au completelyfrom
using ethyl acetate. Ethyl ether has been used to
95% of AU+3 from a 6~ HC1 solution.(17)
Gold canbe completelyseparatedfromPdj Pt,
a 10$ HC1 solution
Beparateat leaat
Rh, Ir, RUJ but not
+4from 0s , by extractfig 3 ~ 13Br solutionsof the metals with isopropyl
ether\ 18)
West, e t al .,(19) +3have shown that Au can be partially extracted
from an Iodide system into methyl isobutylketone,methyl isopropylketone,
ethyl acetate and other solvents. +2 areu+3, ~+3, Hg+2, Cdw, ~ ~
completelyextracted from 6.9 ~ HI solutionsfito diethyl ether (4:1(20) +4volume ratio). AS+3, Bi+3, CU+2, M04, Te , and Zn +2 prtially
etiract under the same condltiona,whereas,K, Cs, Ba, Ca, Fe2, Ni,
Cr, Co, Mn, Ti, Zn, Pb, Th, Al, Ga, Be, U, V, Pt, Pd, Ir; 0s, andRu
do not ext rac t.
Bock and Bock(21) ~ve Shm -t AU+3 can be quantitativelyextracted
@, ~+4, ~+4 T1+3, Hg+2, Crk, Ce ,n to diethyl e ther f rom 8 ~ KN03.+4
>
5 show varied degreI+3, AS+3 and P es of extractabilityunder the same
conditions.
Whi te j=) in his use of alkyl phosphineofideshas shown that t ri -
n-octylphosphineoxiciein cyclohexanewill completelyextractAu l(as
+6 +4 3 MO%, S n+4 , L@, and Zr*) from 1 MHC1. Sb+3,ell as Cr , Hf ,Fe,
Bi+3 cd+2, ~+3, Hg=, pt+2, and ~+2> partially extract in this system.
In a separate study, White(22)
1 (and Sn+4 andas also shown that Au
UA) can be completely extracted from a lljHC1 solution with tris-2-ethyl-
+1n-hexylphoepbine oxide in cyclohexane; however, Au will not extr act
frum a 7 g HC1 solutionusing the same reagent.*+4 +6 +3
,U , Ga , m+4,~e+3 +6 ad ~r+k, MO completelyextract under these latter conditions.
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b. Chelate C omplex systems
Oold (asw ell as Co, Bi, Cd, Cu, Pb, Hg, Ni, T1 and Zn) forma a
water insolublecompoundwith 2-mercaptobenzothiszolehat cm be extracted
+3 till fom a com-into alcohol or ether.(23)
Beck(24) re~rts that Au
plex of thiosalicylideneethylanediiminehat is extractableinto chloro-
form. This AU+3 +2 +3 +4 +2complex (as well ea those for Ni , k , Te , Sn ,
Sb+3 Cd+2, Pb+2, P t+2, and Pt~) is stsble in HC1.
The Au+s complex of phenylthioaurea(like those of Ir +4, ~+3, ~+3,
~B+4 +3 ~+3, ~i,Fe,+2
, and CrA) t ill on ly part ia llyext ract (1*) into
ethyl or SJIIY1cetate from a dilute HC1 solution.(25)
Under these same
Conattions,~d+2 completelyextracts;large amounts of Pt 4 (40~)
~+2 (16%) a lso canbe ext racted in the same system.
Gold, followlngits interactionwith RhodamineB, .sxanthone
can be extractedinto either Isopropylether (26) or benzene>q)
and
dye,
ht imony
emd thalliumalso react with RhodamineB and till etiract into benzene. (27)
Gold forms a faint yellow cmnplexwith ephidrinehydrochloridethat
(28) ~B+8csm be extracted Into CC14. , Pd, and Ir also form colored com-
plexes in this systemwhile Pt and Rh do not.
Poluektov(29)hag used a 0.03% solutionof ett iuc p-dimetbylemlno-
benzalrhodanlneb produce a pink-violetgold complex that can be extmcted
from .amacid solutionwith a benzene-chloroformndxture. Silverwill not
interfereIf i t is f irst separatedas the chloride.
Sandell(30) reports that gold dithizonatecan be extractedfrom a
dilutemineral acid solutionwith chloroform. If carbon tetrachloride
+3Is used, a f loe wI1l appear, and i t is postulated that Au is probably
~duced to **+1 by the CC14.
5 . Separationsby Ion Exchange Resins
Burstall,et al., (31) have shown that
anion exchangeresins till abgorb the gold
Co and Cu also form cyamlde
same Cotillions. These can
complexesthat
quaternary ammnlum strong-base
cysmlde complex,AU[(CN)2]-2.Iii,
absorb upon the resti under the
be selectivelyeluted from the resin ulth dilute
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HC1 and NaCI?solutions. Following the elution of these anions, more than
95$ Or the gold comPlex can be removed with an acetone-HCl solution.
Kraus and Nelson(32)
report that at least 99.9$ of the gold content
of a 0.0014 ~ solution of Au(III) in 1 ~ HC1 could be separated rapidly
(in 5 minutes) from many other elements by the use of an ion exchange
column containing 0.10 gram of Dowex 1 resin. Gibbons also confirmed
this effect by use of Deacidite FF ion exchange resin.
6. Separations By Paper Chromatography and Electrophoresis
*U+3can be separated by paper chrom&tography techniques using either
butanol-1 N HC1, (34) alcohol-HCl mixtures, (35,36) binary alcohol mixtures
containing HC1, (37) ketone-HCl mixtures, (38) butanol-HBr mixtures} 39)
and phenol(40) .sssolvents. Small amounts of gold (1 ppm) in chloride
solutions of the platinum metals have been determined by paper chromatog-
raphy using either an ethyl ether-HCl-methyl alcohol mixture(41)
or butanol-
HC1-H03 mixture as a solvent. Gold can also be separated from almost
all of the other metals using an ethyl acetate-water-HNO mixture as a3
solvent.(43)
It has also been separated from F% and Pd by use of ethyl
(1,4)ether-HCl mixture as a solvent.. Gold has also been separ~ted from
copper, s ilver, plat inum and pal ladium by butanol-HCl mixture(45) ~a
from iridium,platinum, palladium, rhodium and ruthenium with butanol-
HC1-HN03 mixtures(46) as solvents. Methyl ethyl ketone-HCl and methyl
propyl ketone-HCl solutions have also been used to separate it from
(1,7) Inosmium, platinum, palladium, rhodium, iridium and ruthenium.
all of these separations, gold is extracted with the organic phase which
travels ahead of the aqueous irent.
*U+3 +2may be separated from Hg
+4 .-1-3and Pd+2, but not from Ir , B~
and T1+3 , with a voltage of 3 .6 volts/cm applied.to a chromatographic
paper immersed in 0.5 ~ HC1. (48) The above ions are present as snions.
Isoelectric ca+2and the
=+3 +2,Pb +3 ~02+2 ,,Cr,
sr+2 +2, and Ba were also
+6 +4cationic species of MO , Zr , Rh+3, AS+3, Sn+2,
~i+4 +2, Be , Fe +3, co -!-2, N1 +2 +2+2, A1+3, CU ~Zn,
separated under these conditions.
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Mueller, gamma scintillation smd proportional counting methods.(66-69)
Although this monograph is conce rned with measurements of the gold
radionuclidesafter a rsdiochemicalseparation,it should be noted that
some of these counting methods have been emplo~d in the direct (or non-
destructive) analysis of neutron-irradiated dimnonds,(70) semiconductor
(71,72)materials, petrochemicals}73) and metals and a lloys. (73)
VTI. COLLECTIONOF DETAILEDRADIOCHEMICALPROCEDURESFOR GOLD
The radiochemicalproceduresthat now exist for the determination
of the gold radionuclideshave evolved from Ideas and techniquessimilar
to those reported in Section III of this nmnograph and reflect on the
requirementsof each investigationthat has been undertaken. Both carrie.r-,/
free and carrier separationtechniqueshave been employed.
The carrier-freemethods have been employed in the preparationof
radioactivegold tracers.(74-76)
Th e other solvent extractionsepar&-
tions, ae well as the chromatographymethods, repotied in Section III
above, suggest possible carrier-freeseparationsfor the radioactivegold
isotopes.
Carrier methods have been used In the preparationof radioactive
goldtracers(76) and separatinggold from fission prgducts. (77) In addi-
tion, carrier methods of rdiochemical analysis have been used to deter-
mine gold by radioactivation analysis. (78,79) Theprocedures that have
been used in the radioactivationanalysisdeterminationof trace gold
in biologicalmaterials,33%-63) meteorites,50-5356) rocks and
minerals, (53-56) semiconductormaterials,71) p&rochemicals(64) and
sea water(~) are include~as part of this collectionof radiochemical
procedures. However, it should be noted that the proceduresdeveloped
by Tobias and llmn(58)
and by Gibbons for the analysis of gold in
biologicalmaterials me usually followedby most investigators. S5mi-
larly, the procedures proposed
for the analysis of meteoritic
investi~tors.
by Brown and Goldberg and by Smal.es(53)
materials are used frequentlyby other
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In eachof the rediochemlcalproceduresthat follow, special inform-
tion regarding the procedure~B use, the type of nuclear bombardment, the
type of material malyzed, separation time, etc., appears as part of each
procedure. Whenever p0~8ible, an evaluation of each procedure is tie
with regani to its u8efulne8s in the decontamination of other radioactive
species from the radioact ive gold Isotopes.
PROCEDURE 1
Procedure Used in: Preparation of radioactive
Method: Solvent extract ion
tracers
Element Separated: Carrier-freegold radioactivity
Type MaterialBombarded: Platinum, iridium (Note 1), mercury, or gold(Note 2)
_ of Nuclear Bombardment:
Procedureby: Wilkinson -
SeparationT*: w minutes
Yield of Gold Radioactivity:
a)
b)
60 cy clotron (37 W alphas, 9.5 Mevprotons, 19 Mev deuterona)184 cyclotron (388Mev alphas, 348 Mev
Decontmaination: Decontemhatee
EqtipmentRequired: Standaxd
protons, 194 Mev deuterons)
Hicks (Reportedby Meinke (76),
to 4.0 hours
.100%
PFKEEDURE
1. DissolvePt,here)
2. Chlorideion
well from Pt, Ir snd Hg radioactivities
Au, orHg in~uaregia. (AuCla c arriermaybe addeda
mat be greater than 6 N (Hg extracts),and the solu-tion shakenwith an e.&l volume of &yl acetate (gold in organiclayer) @ layers separated.
Notes:
1. See Wickers,E. , Schlect ,W. G., and Gordon, C. L., J . Nat. Bur.Staud. Research3, 363 (1944) for method of dissolvingIridium.
2. This procedure canbe used as a carrie rmethod alBo.
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PROCEDURE1 (Continued)
3 .. Wash ethyl acetate layer twice with equal volume 6 ~ HC1.
4. Evapomte e thyl acetate layer to dryness and take up res idue in 1 ~HC1.
5 . Bubble in S02 to reduce Au+3 to Au in the hot so lut ion.
PROCEIX RE 2
ProcedureUsed In: Pre~tion of.radioactivetmcers
Method: Solvent extraction
Element Separated: Carrier-freegold radioactivity
~ MaterialAnalyzed: Tracer mercury
Type of Analysis: Milking experiment
Procedureby: R. W. Fink (Reportedby Meinke (76)]
Sepmtion Time: .10 minutes
Yield of Gold Radioactivity: @tltative
Decontamination: 103 from any Hg radioactivity
EquipmentRequired: Standard
present
PRWEDURE
1. Take Hg tracer in 4 ml of .3 N HC1 end extractw ith ~O:A of 1s-1ace ta te. (Thef romHg.) -Au
presenceof atleast0.1 N Cl-is requiredfor a sepn.into the organic layer.
2. Wash the organic layer with equal volume sa t. NH4C1 soln. to insuresepn. from ~.
3. Plate organic layer for Au sample.
Note: Tl, if present,will followAuin the solvent ext=ctlon.
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PRocxmm 3
ProcedureUsed in: Preparationof radioactivetracers
Kethod: Solvent extraction
Element Separated: Cold carrierand gold rsdioactivi~
Type MaterialBombarded: Gold leaf
Type of NuclearBombardment: 184 cyclotron (high
Procedureby: Thompson and Rasmussen (Reportedby
SeparationTime: 4-10 minutes
ChemicalYield of Carrier: -100~
energy protona)
Meinke(76))
Decontamination: Fac tor of x f rom Hg and spallat ion
EquipmentRequired: Standard
PROCEDURE
1.
2.
3.
4.
5.
Dissolve Au In warm 6 N qua regim (2 ~ HN03, 4~tube. Work in small v~lume ( l-2ml.).
Add ho ld-back carrie rs for Hg, Pt, Ir, and 0s (--1
productE
HC1) in centrifuge
mg each) .
Add (1 to 1/2 ml.) ethyl acet ate. Agitate,mixing phases wtth transferpipette. (Yellow color of gold quantitativelyextracts into organicphase.)
Magh the seuaratede thvl ace ta te ~hase once or twice with 6 NHC1. (GHg, although
The solutionon the p late
chemistry.
wash of high chloride concentrationserves to r&noveT1 If present WY not be entirelywashed out.)
of Au in ethyl ace tate my now be rapidly evaporatedfor countingor subjectedto further specific gold
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PROCEDURE 4
Procedure Used in: Preparation of radioactive tracers
Method: Fusion and solvent extract ion
Element Separated: Gold csxrie r and gold rtiioactivity
!Pyp=Material Bombarded: Iridiw.ufoil
Type of Nuclear Boniba~nt: 184 cyclotron (388 Mev alphas,protans, 194 Mev deuterons)
348 l.lev
ROCedUR by: (76),Thompson snd Rasmussen (Reportedby Meinke
Sepamtion Time: 20-30 minutes
C@mical Yield of Carmler: 7C14
Decontamination: 102
F@Qment Requi red: Stsndad
PROCEDURE
1.
2 .
3.
4.
5.
6.
Make a melt of KOH and KNO (.50-50,not2elain crucible,heating s rongly over a
To this hot flux add the tarmt Ir metal.
critical)in aFisher burner.
small por-
heat (andontinuingtoaddinu KOH if volume of f lux-nets too sn&l l] unti l the meta l is com-ple tefi dissolved. (For a sal st rip of l -ro ilfoi l, thi s shouldtake no longer.than 5-10 min.)
Allow flux to cool , then leach for -5 min. with cone. HC1, addingAu and Pt carriers i n small amouut. (Ir gives strongbluecolored .Soln.)
Extract twice with ethyl acetate to removeAu.
Combineor&nic layers and wash twice with equal volume 3 ~ HC1.
Plate organic layer and flsme.
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Type of Analysis:
proCdUR by: G.
PROCEDURE
1. To the senmle
2.
3.
4.
5.
6.
7.
8.
9.
10.
Separation
A. Cowan in
PROCEIXJRX5
of gold from fission products
report compiledby Kleinberg (77)
containedin 20 ml of 1 M HC1 in a 40-IDJ .onlcel cent ri fugetube, add 2 ml f 5X sul fosa licyl icac~d solut ion,2.00 ml of AU carrier,1 drop of Te +% holdback carrier, and 1.5 ml of cone. HI. Heat on astesmbath for 10 to 15 min. Centr ifugeand discard the supernate.
Y1.sahut chlorideion by filling the centrifugetube vlth H20 anddecanting. Repeat. Digest the Au precipitatewith 1 nil .f cone.HTJ03,boiling for 1 tin in the hood. Centrifugeand discard thesupernate.
Fill the t ube with ~0 end decant. Dissolve the precipitate in 2 mlof cone . HC1 and 3 to 4 drops of cone. KN03. Boi l off a ll the HN03.
Ellute to 20 ml with 1 ~ HC1 and repeat Steps 1-3 two additional times.
Dilute the solution to 20 ml with 1 ~ HC1 and add 3 drops of Ag carrier.Centrifugeand transferthe supemate to another ~-ml centrifugetube, discsxdingthe &Cl precipitate.
Add 4 tips of Fe carrier, and then a s ligh texcess of cone .NaOH.Without delay, centrifugeand tramsferthe supernateto a clean @-mlcentrifugetube, discardingthe Fe(OH) precipitate. immediately
2eacidi fy the superna tewi th cone. HC .
Add 1.5 ml of cone. HI ad reprecipi ta temeta ll icAu as before (Step1). Dissolvethe precipitatein a minimum amount of aqua regla.
Wash the so lu tion into a 125-mlsepara tor funnelwith about 40 mlof 1 14HC1. Extrac twi th 25 ni lof ethy l ace ta te . Wash the ethylaceta~e layer ttice wLth 5-nilportionEof 2 ~ HC1.
!krsmsferthe ethyl acetate extract to a 1.25-mlErlenmeyerflask S,ndremove the ethyl acetate on a steambath. Add 25 nilof 1 M HC1 and1.5 ml of cone. HI. Heat on st=bath for 10 to 15 tin ~ precipi-tate metallic Au.
Filter the Au on a weighed No. 41 HWhatmsn fil ter circle, 7/ 8 diemeter,using a .groti=offHirsch funnel and a fil ter chimuey. Wash the pre-cipitatewith 1 l.!C1, and then with acetone. Dry for 15 min at 11O.cool, weigh, and-mount.
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PROfXIXJIW6
ProcedureUsed In: Radioactivationanalysis
Method: Fusion, solvent efi=ction, and precipitation
Element Seprated: Gold carrier and Au19!3 radloactitity
Type of MaterialAnalyzed: Igneous ro ks 7(53) *emIs, (54,55,57)
stoneymteorites 551
~ of Nuclear Bonibardment: *ulg7 (n,y)AulX
Rrocedu by: Smales,A. A., (53) Vincent, E. A. and Snal.es, . A. (54)
ChemicalYield of carrier: w
SeparationTim: Not stated.
DecontaminationFactor: Adequate from other radloactitities
EquipnentRequired: Standard
PROCEDURE
1.
2.
3.
4.
5.
6.
7.
ti the lrrsd. sample (powder)with about 0.5 @n N~02 in a silicacruc ibleand heat at ~0-500C in the muff le for ten minutes. Trans-fer the cooled Binteredcake to a small beaker, mpisten with waterand add 30 mg Au foil (these carrier foi ls - convenient lyweighedout in sdvance), Add aqua regia to the cmcible and loosen any eilher-Ing matefial w ith a glass rod. Mgest on the hot plate for a fewminutes and trasfer the acid to the beaker contain= the sfnteredcske,~d cmrier. Repeat the acid digestionof the cruciblecontents;finally rinBing into the beaker with a ldttlewater.
Cwer the beaker and evapora te the contents to drynesson a hot p late;cool, add fresh aqua regla, and repeat the evaporation. Take up theresidue in 1 ml HC1 md 20 ml of ~0, and tmsfer to a centrifugetube.
Centrifugeoff the silica and t~fer the supernatantto a freshtube. Wash the sil ica twice with hot, dilute HC1 adding the ~hingato the main solutlon. Discard the silica to active waste.
To the main solu tion,add 10 mg as cationsof holdback car riersNa,K, and Cu and 5 mg of holdback carrier Co, h andlfn, followedbysufficient_esium powde r to precipitatethe Au metal , and leave as light excess . Warm to expel hydrogen.
Centrifugeand decant the supernatantto active vaste, and wash theprecipitatedmetal twice with hot water.
Dissolve the precipitatedmeta l in a fw drops .ofaqua regia andevaporatenearly to dryness. Dissolveresidue in 15 ml of 10%HC1and transfer t o a separating fuonel. Ertractw ith ~ ml of ethylacetate,discard the aqueous layer to active waste.
Wash the ethyl acetatesolution containingthe gold twice with 20ml of lC$ HC1. Run the ethyl acetate layer Inta a beaker and eva~rate
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PRa2mmm 6 (Conttiued)
to dryneaa on a hot plate and Ciiasolvethe residue Inof aqua regla . Transferthe solutionwith water to a
8. Add 2 ml of HC1 and holdback cartiersof Na. K, Co,
a few dropscentrifugetube.
cu. Zn. Sndkhl... .Heat nearly to boiling and add about 0.5 gm I&3roquinone. After stm-d-ing for a few minutes Heparatethe gol& metal by centrifuging. Wash
the gold twice with hot water, red isso lvein a few drops of aqua regla.
9. Repeat step 8 three more t imes. Fina llywash the gold metal twicewith water and then with alcohol. Tramfer to a weighed countingtray, dry under a infra-redlamp and weigh to establishthe chemicalyield.
PRocm 7
Procedure Used In: Radioactive.tlontiysls
Method : Fusion, solvent extractionend precipitation
Element S epmted: Gold carrier md Aulg3
radioactivity
Type of Material Bombsmied: Iron meteorites (50-52)~dgeawatir(~)
(see Note)
Type of Nuclear Ekmibardm=nt:Aulw
(n,y)Aul*
Procedureby: Goldberg,E. D. and Brown, H. (50)
ChemicalYield-of Carrier: 75%
EquipmentRequired: standard
PROCEDURE
1 .
2.
3.
4 .
Dis s olv e 0 .3 to 0 .5 g of irradiatedmeteorite i n 20 ml of aquaregla. Add 30 mg of Au carrier. Evapozate t o dryness.
Take up res idue in 30 m l bf 10~HC1. Wtract with ~ ml of ethylacetate. Wash the ethyl acetate la y er tw ice with 20 ml of 10~ HC1.
Evaporate t he ethyl aceta@ layer to dryness on a steam bath. Takeup the residue with 15 ml H@, 5 ml cone. HC1. Bfing the solutionto a boil aud add 10 ml of a 5X aqueous solution of hydroquinone.Continueboiling for 20 minutes or until the gold metal coagulatesinto lumps.
Fi lte r the gold metal on l -cm paper c ircles . Wssh with 25 ml port ionsof hot water & one 25 ml portion of ethyl alcohol. Dry for 15minutes at llOC and detemrdnethe weight OT precipitatedgold.
Note : Humme~!n his paper on the determinationof gold In s ea w a tercates that the procedm of Goldberg and Brown was followed.
indi-
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ProcedureUsed In: RadioactlvutionSnalyeim
Type of Matel%%l Analyzed: Sllitml
~ of hCkar B~t : Auln(n, 7)Au1*
Roceaureby: Jms, J. A. and Ric hards , D. ,.(71)
c hem ic al Yield of Her : Thl lmmn
SePEuation mm?: unknown
DecontaminationFactor: Adequate frm other nsdionuclidem
I$qui~ Required: Skudard
Ho&: ~ E~ifiC infommtiozlhsa been == a thiS ~C8durS .Ptiblicatiaashould be consulted.
FmQmumg
Pmeaure used h: Radioacti?ationlalyeis
Me-tbd: Bolvent Sxtmmtion sad precipitatim
Element Semted : Oold c~er end Aul* radioectiti@
Type of Material Analyzed, mtrochendcals(~~
Typ3 of Hucleer B4mibardvsmt: Au1W(n,7)Aulga
Procedureby: ~, E. A. (RsPortedby kddiCOttS (6411
Clumdcal Yield of ~er: At least 7%
sel==tion ?!im3: 2 hmun
Degree of Purification:~~~=~ 0 ~ o*r m8dioel~t8
A. Imaalatian of Sample Matitiele
1. Irm d iabs k now n am oun ts of teat end c~tor (0.025 to o.om g ofgold metal to nearest O.1 mg) samples in a neut ronf lux of at least
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PRWEI)UKE9 ( Continued)
5 x 1011 n/cm2/secfor 16 hours (Note 1). Use small quartz tubes ,polyethylenebottles or slumlnumfoil to contain the samples.
B. Rrepam tlon of Irz%ilatedSamples forAnalysis
1. The Odd Compr ator Sample
a.
b.
c.
Quantitativelytransfer the irmdlated test portion of the goldcomparatorsample from the quartz tube or alumlnumwrap to a 100-mlvolumetric flask. Disso lve the tes t por tion h a small ,waeumsdvolume of aqua regia (4 ml HC1 to 1 ml HNO ); thendilute thesolut ionto 100 ml ulth water. ?ix the so ution wellby shakingit carefully. Obsemre the rules for the atie handlhg of radio-active materials that are outlinedin Method No. 5 0050, Sdety.w
By means of a volumetricplpet, plpet a 0.100 ml allquot of thissolutloninto a second 100-ml volumetricflask; then dilute thea llquot to NXl ml with water.
Shake the solutionthoroughly;then pipet a l .00-zU allquot of itint roa ~-ml glass centr ifugetube. By means of a volumetricpipe t,add to the same centrifuge tube 2.00 ml of a standard carriersolut ionof known gold concentn3tion . Also add 1 ml each of hold-back chers of cadmium,cobal t, copper, i ron, manganese ,phos-phorus, sodium, and strontium.(Note2) Continuewith Pert Cbelow.
2 . SoUd PetrochemicalTest Seraples
a. If the sample is a solid, or semi-solid,petrochqnical ,quanti-tat ivelytransfer the irmdiated test portion from the quartztube or a luminumwrap to a lx-ml glass Erlenmeyerflask, and thenadd, by means of a volumetricp lpe t, to the same f lask 2.00 ml ofa standard carrier solutionof lomwn gold concentration. Alsoadd 1 ml each of holdback carriersof cedmlum,cobalt ,copper,iron, mnganeee, phosphoznm,sodium and strontium (Note 2). Tothi~ ~ure, add 15ti of w -H2H04 mixture (2 volumes of 6X
dN03toone volume of cone. * 4). Also, put 2 or 3 glass bedsInto the f lask , then diges t the solut lona t a mode=te tempera ture(60C)until all of the petrochemicalis destroyed (Note 3). Con-tinue heathg until all of the BN03 is removed from the solution.Cool; t ransfer the solut iont it s a ~-ml centr ifugetube and thencontinuewith Part C below.
3. Liquid Petnchemical Test Samples
a . I f the sample ie a l iquid pet rochendcal ,p ipet an a liquot of theirradiatedportion into a 125-ml glass Erlenmegmrflask, and thenadd, bymeaos of avolumetr lc p ipet , to the same f lask 2 .CX3ml ofa stxmdardcaroler solutionof lumwn gold concentration. Also dd1 ml each of holdback c~ers of cadmium, cobalt, copper, iron,manganese ,phosphorus , sodium and s tr@lum (Note 2). To thisndxture, add 15 ml of ~3-H2~l+mixture (2 volumes of 6m~3to one volume of cone. H@04). Also, put 2 or 3 glass beads intothe flask, then digest the solutionat a moderate tempe=ture(60C)until all of the petrochemicalIs destroyed (Note 3).
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PROCEDUM9 (Continued)
Continueheating unti l a ll of the KN03 is removedfrom the EIolu-tion. Cool; transfer the eolutioninto a 50-DiLcentrifugetubeand then continuewi th Part C below.
c. HadiochemicalSeparatlon of Gold
1 . Concentmte the solution to a volume of 2 or 3 ml. (Note 4)
2. To the hot solution, add still aumunt~ of zinc metal powder (2U mesh)until no further precipitationtakes place and an excess of zinc metalpowder exists. Centrifuge;discard the supernatantliquid.
3 . To the precipitate add 1-2 ml of cone. HC1 to dissolvethe excesszinc metal. Then, add enough dis ti lledwater to make a volume of20 nil. Stir the ndxture thoroughly. Centrifuge;dlscemi thesupernatantliqtid. Wsah the prec ipi ta tewith 10 ml of hot water;stir while adding water. Centrifuge;discard the water wash.
4. Dissolve t he precipitate in 0.25 mlHN03 and 1.0 ml ofHC1. Heatto completedissolution. T!mmsfer to a 50-ml se~tiry funnel.Wash the centrifuge tube ulth 4 ml of 3 N HC1; add the washes tothe separator funnel.
5. Add 10 ml of ethyl acetate to the separa tor funnel . Ertrac t thegold ions frnm the aqueous solutionby shaking the m ix tu re th orou gh ly .Allow the phases to separate;remove ad discard the aqueous phase.Wash the organic layerby adding 10 ml OP 3 ~ HC1 to the separatorf lask and shakingthe mixture . Allow the phases to sepa~te ; remaveand discard the aqueous phase.
6. Tmsfer the organic p hase to a ~-ml centrifuge tube. Add 2 ml of0 .1 ~ HC1 and remove the e thyl acetateby slowly heating the mbr ture(Note 5) inamter bath. Wnen all of the ethyl acetate has beenremoved,transferthe solutionto a new ~-ml centrifugetube. Rinsetube with 2 or 3 ml of 0.1 N HC1 and transfer rinses to the new cen-trifuge tube (Note 6).
7 . Heat the solution to boiling. Then add solid scdlumbisulflte, NaHS03,
to reduce the carrier and precipitate elemental gold. Digest themixture for 10 minutes by heating h a water bath. Stir the mixturefrequently during the digestion process . (Note 7)
8 . Filt er o ff the gold through a tared fil ter paper (MunktellsNo. 00)tha t i s he ld h a Hirsch funnel ;wash the prec ip ita te three theswith 5-Inlpor tionseach of H20 and hot HN03. Then, repeat waterwashes. Wei@ the gold precipitateand f il te r paper on an analyt ica lbalance. Mount the precipitateand count its radioactivityasinstructedIn Part D below.
D. Heasureme nt Of the RadioactivityFrom AU lg8 ~
Calculationof hactive Gold Content of theOriginal Sample
1. coun t ing of Beta Radioactttity
a. If the beta radioactivityfrom AU1* in the gold precipitate Is tobe counted, t r ane fe r the precipitateand fil ter paper to a watchglass. Mount the watch glass and i ts contentson a cardboardmount
28
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PRocEDum 9 (Conthled)
b.
c.
d.
e.
By means of a Geiger-Muellercounter and for the comparatorsample,determine the backgroundbeta radl.oactivltynd the beta radio-activity of the precipitate. Record the time at which the betaradloactititywas measured.
Also, for the teBt sample, determinethe backgroundbeta radio-
activityand the beta radioactl ti tyof the precipikte. Recordthe the at which the beta rmiioactlvitywas measured.
I f I t I s neceesary to make a correc tionfor decay, sele t somereference t= from which the decay correct ionfor AU1 ~ can becalculated. This referencetime might possiblybe the same t-as the countt ig t ime for the fi rs t sample aualyzedor i t mightbe sane earlier t ime.
If the de-e of the mdiochemlcal purity of the precipitate isnot knoun~ check it by countingthe-beta-tioactitity at periodicintervalsuuder the same conditionsused to determinethe initialcount or by making a beta absorptionstudy.
2. countingof Genm.aRadloactitity
a.
b.
c.
d.
A
If the gemma radioactivityfrom Au1*
In the gold precipitateIsto be couuted,transferthe precipitateto a pyrex culture tube(lolIRnx75 mm, w/ortnl).
For the comparatorsarqple,detenulnethe background radioactivityand the _ radiwctivity of the precipitateeitherby meansof a gamma scintil lationcounter,by @mma Mscrtinatory counting,or by gaum scintillationBpectrometry. Record the time at whichthe gamma radioactivitywas measured.
Also for the test sample, determinethe backgroundgamma radio-activityand the gamma radioactivityof the preclpltite. Recordthe the at which the gamma rti ioactl ti tywas measured.
I f it is necessay to make a correc tionfor decay, se lect somereferencetime from which the decay correctionfor AU1% can be
calculated.
cqfison Of the correct~ radloactivitiesfor the test and Com-
parator samplesbecomes a measure of the stable gold content of the test
sample:
Percent Stable Gold In Test Sample=
CorrectedAU1* Radioactivityh Test S9mple
CorrectedAU1* Radioactivityin ComparatorSemplex 100.
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mocm 9 (Continued)
Notes:
1.
2.
3.
4.
5.
6.
7.
The Oak Ridge National LaboratoryGraphiteReactor was used forthe irradiation. The sensitivityof the method is such that1 x 10-9 gmm of gold can be determined. The sensitivity canbe enhaced by the use of higher neutron fluxes.
Solutionsof the ions of other elementsmay.also be added asholdback carriers.
From 1 to 2 hours will be requiredfor dige6tfon. AdditionalHN03 til l have to be added during the digestionperiod.
Solution s hould be cle= and yellm in color. If not, or a pre-cipitateforms, add cone. HC1 and cone. IDK13dropuisewhileheating.
Use a wel l vent ila tedfume hod for this oprat ion .
The ethyl acetate t ill form a coatingon the walls of the cen-trifuge tube and will absorb enough of the fine gold precipitateobtained in Step 7 to cause low experimental yiel ti.
HYdrOquinonecanbe ueed instead of NsHS03 asThe same techniquesgiven in this step should
the reducingbe followed.
agent.
30
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AFPENTIIX A
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34