Else ie Edi o ial Sys em( m) o Analy ica Chimica Ac a
Manusc ip D a
Manusc ip Numbe :
Ti le: Isola ion o Pu-iso opes om en i onmen al samples
using ion ch oma og aphy o accele a o mass spec ome y and alpha spec ome y
A icle Type: O iginal Pape
Sec ion/Ca ego y: SEPARATION METHODS
Keywo ds: Plu onium; AMS; alpha spec ome y; TEVA
Co esponding Au ho : Physicis Elena Chamizo,
Co esponding Au ho 's Ins i u ion: Cen o Nacional de Acele ado es
Fi s Au ho : Elena Chamizo
O de o Au ho s: Elena Chamizo; Ma ía del Ca men Jiménez-Ramos, PHD S uden ; Lukas Wacke , doc o ;
Ignacio Vioque, Doc o ; Ana Calleja, PHD s uden ; Ra ael Ga cía-Teno io, p o esso ; Manuel Ga cía-León,
p o esso
Abs ac : A adiochemical me hod o he isola ion o plu onium iso opes om en i onmen al samples,
based on he use o speci ic ch oma og aphy esins o ac inides (TEVA®, Eich om Indus ies), has been se
up in ou labo a o y and op imised o hei pos e io de e mina ion by alpha spec ome y (AS) o
accele a o mass spec ome y (AMS). The p oposed adiochemical me hod has eplaced in ou lab a well-
es ablished one based on he use o a ela i ely un-speci ic anion-exchange esin (AG® 1X8, Bio ad),
because i is clea ly less ime consuming, educes he amoun s and mola i ies o acid was es p oduced, and
ep oducibly gi es high adiochemical yields.
In o de o check he eliabili y o he p oposed adiochemical me hod o he de e mina ion o plu onium
iso opes in di e en en i onmen al ma ixes, win aliquo s o a se o samples we e p epa ed wi h TEVA and
wi h AG 1X8 esins and measu ed by AS. Some samples p epa ed wi h TEVA esins we e measu ed as well
by AMS. As i is shown in he ex , he e is a com o able ag eemen be ween AS and AMS, which
adequa ely alida es he me hod.
Isola ion o Pu-iso opes om en i onmen al samples
using ion ch oma og aphy o accele a o mass spec ome y
and alpha spec ome y
E. Chamizo a*, M.C. Jiménez-Ramos b, L. Wacke c, I. Vioque b, A. Calleja b, M.
Ga cía-León a,b, R. Ga cía-Teno io b
a Cen o Nacional de Acele ado es (CNA), A da. Thomas A. Edison , 41092, Se illa,
Spain.
b Applied Nuclea Physics G oup, Uni e si y o Se illa, P.O Box 1065, 41080, Se illa,
Spain.
c Ins i u e o Pa icle Physics, ETH Höngge be g, CH-8093 Zü ich, Swi ze land.
* Co e Le e
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Isola ion o Pu-iso opes om en i onmen al samples
using ion ch oma og aphy o accele a o mass spec ome y and alpha
spec ome y
Abs ac
A adiochemical me hod o he isola ion o plu onium iso opes om en i onmen al samples, based
on he use o speci ic ch oma og aphy esins o ac inides (TEVA®, Eich om Indus ies), has been
se up in ou labo a o y and op imised o hei pos e io de e mina ion by alpha spec ome y (AS)
o accele a o mass spec ome y (AMS). The p oposed adiochemical me hod has eplaced in ou
lab a well-es ablished one based on he use o a ela i ely un-speci ic anion-exchange esin (AG®
1X8, Bio ad), because i is clea ly less ime consuming, educes he amoun s and mola i ies o acid
was es p oduced, and ep oducibly gi es high adiochemical yields.
In o de o check he eliabili y o he p oposed adiochemical me hod o he de e mina ion o
plu onium iso opes in di e en en i onmen al ma ixes, win aliquo s o a se o samples we e
p epa ed wi h TEVA and wi h AG 1X8 esins and measu ed by AS. Some samples p epa ed wi h
TEVA esins we e measu ed as well by AMS. As i is shown in he ex , he e is a com o able
ag eemen be ween AS and AMS, which adequa ely alida es he me hod.
1.- In oduc ion
Plu onium is an an h opogenic elemen ha has ound i s way in o he en i onmen since he
beginning o he nuclea age in 1945. Among he di e en ac inides eleased due o nuclea
ac i i ies, Pu dese es a special a en ion om he poin o iew o adioecology and oxicology.
The main sou ce o Pu o he en i onmen we e he a mosphe ic nuclea weapons es s ca ied ou
mainly in he 1950’s and he 1960’s, which in oduced 0.3 TBq o Pu in a global scale [1].
Addi ional amoun s o his elemen ha e been eleased a a local scale as a consequence o ci il
nuclea eac o acciden s (as he Che nobyl acciden ), eleases om nuclea ep ocessing acili ies
(as Sella ield, UK; La Hague, F ance; Mayak PA, Russia) and nuclea weapons acciden s
(Paloma es, Spain; Thule, G eenland).
* Manusc ip
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Among he ou majo plu onium iso opes (241Pu, 238Pu, 239Pu and 240Pu), h ee a e alpha-emi e s:
238Pu (T1/2=87.7 y, Eα=5,499 MeV (72%)), 240Pu (T1/2=6564 y, Eα=5,168 (76%)) and 239Pu
(T1/2=24110 y, Eα=5,157 (73,3%)). Con en ionally, hey a e de e mined in en i onmen al samples
by alpha spec ome y (AS). Howe e , he wo mos abundan plu onium iso opes, 240Pu and 239Pu,
canno be quan i ied independen ly in low-le el samples due o hei e y simila alpha-ene gy
emissions (ΔE=11 keV). AS usually in o ms abou he joined ac i i y o 239Pu and 240Pu. In many
cases, his is enough o a simple moni o ing o su eillance p og am.
Ne e heless, he s udy o he a io o 240Pu and 239Pu o e s unambiguously in o ma ion abou he
o igin o he plu onium. The 240Pu/239Pu a omic a io anges om 0.03 o 0.06 o weapon-g ade
plu onium, and eaches a alue o 0.4 o eac o -g ade plu onium. This a io can be quan i ied by
mass spec ome y echniques (MS): ei he he mal ionisa ion mass spec ome y (TIMS) [2],
induc i ely coupled mass spec ome y (ICP-MS) [3], o accele a o mass spec ome y (AMS) [4].
Among hem, AMS o e s e y low de ec ion limi s (~1 µBq o bo h 239Pu and 240Pu), making i
possible o s udy hese iso opes in any en i onmen al compa men . On he o he hand, limi ed
in o ma ion on he Pu sou ce e m can be gained by measu ing he 238Pu/239+240Pu ac i i y a io by
AS.
We ou inely pe o m in ou labo a o y he de e mina ion o 238Pu and 239+240Pu in a wide a ie y o
en i onmen al ma ixes by AS. Recen ly, we ha e gained as well expe ience in he ield o he
de e mina ion o 239Pu and 240Pu by AMS [5]. In bo h cases, i is necessa y o apply a adiochemical
p ocedu e o isola e he plu onium ac ion and adap i o op imum physicochemical condi ions o
he inal measu emen : a) he elec o-deposi ion o plu onium on o s ainless s eel disks o i s
de e mina ion by AS o b) he dispe sion o he plu onium in a me al/me al oxide ma ix o i s
measu emen by AMS.
In his pape , we desc ibe a adiochemical me hod, based on he use o he ex ac ion
ch oma og aphy esin TEVA (Eich om Indus ies), o he isola ion o he plu onium om di e en
en i onmen al ma ixes. The ollowing poin s ha e been s udied: eco e y yields, alpha-peak
esolu ion in AS, and he magni ude o he U, Th and Dy decon amina ion ac o s as po en ial
in e e ences o AMS o AS. The necessa y alida ion was pe o med by applying he TEVA
me hod and he con en ional one, based on he AG 1-X8 esin (Bio ad), o di e en samples, and
compa ing he ob ained esul s by AS. Also some independen aliquo s we e p epa ed wi h he

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TEVA me hod and measu ed by AMS. Tha way, he alidi y o he ecen ly adap ed TEVA
me hod o bo h AS and AMS has been checked.
A desc ip ion o he TEVA me hod is gi en in Sec ion 2, i s main cha ac e is ics and ad an ages a e
highligh ed in Sec ion 3 and, inally, he esul s ob ained in he alida ions exe cises a e shown and
discussed in Sec ion 4.
2.- Expe imen al
2.1.- S anda ds, esins, equipmen s and samples
The samples ha e o be spiked wi h a known amoun o 242Pu bo h o AS and o AMS
measu emen s. This spike is necessa y in bo h echniques o he de e mina ion o plu onium
concen a ions by he iso ope-dilu ion me hod: 239+240Pu ac i i y in AS, o 239Pu and 240Pu ac i i ies
in AMS. In AS, his spike can be used as well o es ima e he chemical eco e y yields o he
p ocedu e. The s anda d solu ion o 242Pu was supplied by NPL, England, and was dilu ed o ob ain
s ock solu ions wi h a concen a ion o 20.9 mBq/ml (144 pg/ml) in a 2M HNO3 ma ix.
The ex ac ion ch oma og aphy esin used was TEVA (Eich om Indus ies), which has been p o ed
o be a good op ion o he sepa a ion o e a alen ac inides (Pu4+, Np4+ and Th4+) in 2-4 M ni ic
acid om Am3+ and U6+ [6]. Ready- o-use mini-columns (diame e : 7 mm; leng h: 8 cm) packed
wi h 2 ml o esin (100-150 µm mesh) we e used o hese analyses.
The AS sys em used o he measu emen s was an alpha spec ome e Alpha Analys (Canbe a)
wi h eigh independen chambe s ha can wo k in pa allel. Each chambe was equipped wi h a 450
mm2 passi a ed implan ed plana silicon de ec o (PIPS, 18 keV o nominal esolu ion). The
measu emen s we e pe o med by placing he samples a a dis ance o 1.5 mm om he de ec o . In
hese condi ions a coun ing e iciency o 34% was achie ed [7].
.
The AMS measu emen s we e pe o med wi h he ETHZ/PSI compac AMS sys em Tandy adap ed
o he measu emen o ac inides. B ie ly, he plu onium was ex ac ed om he Cs+ spu e ing ion-
sou ce as PuO-, s ipped o Pu3+ wi h an A s ippe gas a a e minal ol age o 330 kV, and coun ed
wi h a gas ionisa ion de ec o wi h 1.3 MeV o ene gy. This de ec o ea u es wi h a 3x3 mm2
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silicon ni ide en ance window, which is 40 nm hick o op imal sepa a ion o he plu onium ions
om he 2+ molecula agmen s wi h he same M/q a io [4].
The ICP-MS de e mina ions, ca ied ou o s udy he magni ude o he U, Th and Dy
decon amina ion ac o s, we e done wi h an Agilen -7500C mass spec ome e .
The analysed samples we e he ollowings: a) a i icially aced wa e , b) ashes o wood, c)
supe icial soils collec ed in Paloma es (Spain) and d) supe icial soils wi h allou plu onium.
Some o hese samples we e used ei he in he decon amina ion ac o s s udy o in he alida ion
exe cises.
2.2.- P oposed TEVA adiochemical me hod
Sample p e- ea men ( 20 h)
A known amoun o 242Pu (1 ml o he 20.9 mBq/ml solu ion o AS, and 20 μl o he same solu ion
o AMS) was added o each sample (wa e , soils, wood) as a spike, oge he wi h some ml o
dilu ed HCl o i s homogenisa ion.
The solid samples we e d ied a 70ºC o 2 hou s. A e wa ds, hey we e ashed in a mu le u nace
o emo e he o ganic ma e in wo sequen ial s eps: i s ly a 150ºC du ing 2 hou s, and inally a
550ºC du ing 6 hou s. The wa e sample was di ec ly e apo a ed o d yness.
Once cooled, he esidues we e placed in a e lon beake and 20 ml o 8M HNO3 and 2 ml o H202
we e added. A e hea ing a 90ºC o 1
hou , 1 ml o concen a ed HF was added
in o de o enhance he quan i a i e ex ac ion o he e ac o y plu onium ha may be p esen ,
pa icula ly in he analysed soils om Paloma es. The mix u e was hen hea ed o 5 hou s, adding
8M HNO3 o keep he olume a 20 ml. The supe na an was he eby isola ed by cen i uga ion
(4000 pm, 10 minu es). The solid esidue was disca ded.
The supe na an was hen e apo a ed o d yness and he esul ing esidue was dissol ed wi h 1 ml
8M HNO3 and 10 ml o dis illed wa e , gi ing a 0.7M HNO3 solu ion. The plu onium was hen
subjec ed o a edox cycle: educ ion o Pu3+ wi h Fe2+, adding 0.1 g o FeSO4, and oxida ion o
Pu4+, adding 8 ml o 8M HNO3 and 0.2 g o NaNO2. A hese condi ions, he plu onium o ms a
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nega i ely cha ged ni a e complex, Pu(NO3)62-, which is e ained in he column. The ob ained
solu ion (abou 19 ml in a 3 M HNO3 medium) was inally condi ioned o a 0.5M Al(NO3)3 medium
by adding 3 g o Al(NO3)3-9H20, o complex he oxala es ha educe he e en ion o he plu onium
in he column [6]. The sample was hen loaded in o he ex ac ion ch oma og aphy esin TEVA.
Sepa a ion by TEVA esins (4 h)
A e he condi ioning o he comme cially p e-packed 2 ml TEVA esin wi h 10 ml o 3M HNO3,
he sample solu ion was loaded on o he column. A hese condi ions, he Pu is s ick o he esin,
and mos o he U and ma ix elemen s a e elu ed (see pos e io discussion).
The esin was hen washed successi ely wi h h ee di e en acid solu ions: i s ly wi h 10 ml o 3M
HNO3, secondly wi h 40ml o 2M HNO3 o assu e he emo al emaining aces o U and, inally,
wi h 15 ml o 6M HCl o elu e he Th.
In a las s ep he Pu was elu ed wi h 20 ml 0.5 M HCl. The Pu ac ion was hen eady o he
p epa a ion o he Pu sou ce in he o m equi ed o each echnique.
P epa a ion o he Pu sou ce
The inal plu onium ac ion has o be adap ed o an op imum physicochemical medium o each
echnique. In he case o AS, he plu onium in ou labo a o y is con en ionally deposi ed on o a
s ainless-s eel disk, ollowing a well-es ablished elec odeposi ion me hod [8]. Fo AMS he
plu onium, as plu onium oxide, needs o be dispe sed in a me allic ma ix o i s measu emen in a
Cs+ spu e ing ion-sou ce.
To p epa e he AMS a ge , 0.5 mg o Fe3+ (as Fe(NO3)3) was added o he inal plu onium ac ion
om he TEVA esin (20 ml o 0.5 M HCl) as a ca ie . This solu ion was e apo a ed o d yness
(5 h). The esidue was baked a 800ºC in a mu le u nace o 3 hou s o con e he plu onium and
i on o oxides (Pu3O8, Fe2O3). Finally, 2 mg o pu e aluminium powde we e mixed wi h he oxides
and p essed in o a 1 mm diame e aluminium ca hode. Tha way, he sample was eady o be
measu ed by AMS [4, 9].
A comple e low-diag am o he analy ical TEVA p ocedu e p oposed in his pape o Pu
de e mina ion in en i onmen al samples is shown in Fig. 1.
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2.3. - Con en ional me hod
This adiochemical p ocedu e is ully desc ibed in [7]. B ie ly, i consis s o he ollowing s eps:
S ep 1.- The samples a e ashed (in o de o emo e he o ganic ma e ) and hen we -oxidised o pu
Pu-iso opes and o he elemen s in dissolu ion.
S ep 2.- A e il a ion, he dissol ed sample is passed h ough an AG® 1-X8 anion exchange esin,
om whe e a e se e al elu ions (in o de o emo e in e e ing elemen s), he Pu-iso opes a e
s ipped in a e y pu i ied solu ion.
S ep 3.- The Pu-iso opes a e inally elec odeposi ed on o s ainless-s eel planche s. The Pu sou ces
so ob ained a e hen eady o measu emen .
3.- Resul s and Discussion
U, Th and Dy decon amina ion ac o s
In o de o check he eliabili y o he TEVA me hod o bo h AS and AMS, he quali y o he
plu onium ac ion om he TEVA esin has been s udied. In bo h cases, he achie emen o a
pu i ied plu onium ac ion is impo an : in AMS, he PuO- cu en ex ac ed in he spu e ing ion
sou ce imp o es wi h he concen a ion o Pu in he a ge ; in AS, he esolu ion o he ene gy
spec a is closely ela ed o he hickness o he elec odeposi s. Mo eo e , special a en ion mus
be paid o he decon amina ion ac o s achie ed o some ace elemen s ha may be po en ial
plu onium in e e ences in AS (228Th and 241Am) o AMS (238U and 160Dy).
As long as alpha spec ome y is conce ned, i is impo an o emo e aces o 241Am (T1/2=432.2 y,
Eα=5.486 MeV (85%)) and 228Th (T1/2=1.91 y, Eα=5.420 MeV (73%)) in he inal plu onium
ac ion, as hei main alpha-emissions in e e e wi h he ones o 238Pu (T1/2=87.7 y, Eα=5.499 MeV
(72%)) in he ene gy spec a.
In he case o he compac AMS sys em Tandy, 238U may each he de ec o e en when he machine
is uned o 239Pu, due o s aggling on he esidual gas in he acuum sys em o due o ins umen al
1
Table 1
Sample AG 1X8 TEVA
Soil-1 115 68
Soil-2 60 36
Soil-3 70 44
Wa e 50 35
Table 2
Sample Pu eco e y yield (%)
TEVA me hod
Pu eco e y yield (%)
AG 1-X8 me hod
Wa e 76 61
Soil-1 74 54
Soil-2 62 55
Soil-3 68 51
Ashes 60 39
Table 3
AS
Sample
239+240Pu (Bq/kg)
TEVA me hod
239+240Pu (Bq/kg)
AG 1X8 me hod
Wa e 35.0 ± 2.2 Bq/m336.0 ± 2.1 Bq/m3
Ashes 0.08 ± 0.01 Bq/kg 0.08 ± 0.01 Bq/kg
Soil-1 (Paloma es) 49.4 ± 1.0 Bq/kg 46.5 ± 2.3 Bq/kg
Soil-2 (Fallou ) 2.40 ± 0.15 Bq/kg 2.37 ± 0.09 Bq/kg
Soil-3 (Fallou ) 1.48 ± 0.08 Bq/kg 1.44 ± 0.07 Bq/kg
Table 1-4

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Table 4
AS AMS
Sample
239+240Pu (Bq/kg)
TEVA me hod
239+240Pu (Bq/kg)
AG 1X8 me hod
239+240Pu (Bq/kg)
TEVA me hod
Soil-2 (Fallou ) 2.40 ± 0.15 2.37 ± 0.09 2.65 ± 0.14
Soil-3 (Fallou ) 1.48 ± 0.08 1.44 ± 0.07 1.53 ± 0.09
Soil-4 (Fallou ) 1.55 ± 0.06 1.50 ± 0.05
Soil-5 (Paloma es) 0.06 ± 0.01 0.049 ± 0.005
Figu e 1
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Figu e 2
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Figu e 3
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Figu e 4
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