Determination of Sodium and Copper in Ohasari Sea Shell By Radiochemical Neutron Activation Analysis

  D e t e rminati o n o f Sodium and Copper ..

  2 . When peak area is too sm a ll to d etect a nd when it is influenced b y s p ectra of major nuclides . This condition wi ll b ec om e more serious when t h e i nt e rf eri n g nuclides have simil a r or long e r h a lf-l iv es .

  2

  64 Cu . Due to this c ondition , the presence of sodium will i nt e rfere wi th t he detection of 64 eu and it t he n becom es necessar y to remove

  24 Na is sli g htl y lon ge r th a n that of

  34 MeV ga mm a ra y (0 . 5%). The half-lives of

  24 Na , the annihilation radiation at 0 . 511 Me V appears a s a the result of gair produ c tion e ff ec t . On the other hand , Cu nu c lid e emits mainl y 0.511 MeV of a nnihil a t i on r a diation (3 8%) and 1 .

  54 MeV . On the gamma-ra y spectrum of

  4 Na) emits 2 gamma ra y s with the energ y of 1 . 369 MeV and 2 .7

  If there are N a a nd Cu in the same sample , then it will b e difficult to anal y ze Cu . Activated sodium e

  X(n ,ry + IX .

  B a si c Principl e In g e ner a l , w h e n a reaction takes place in neutron ac ti va tion it is written as belows : _n

  a- rays with the same en ergy .

  

Determination of Sodium and Copper in Ohasari Sea Shell

By Radiochemical Neutron Activation Analysis

S udi A r iy anto

  1 . The photopeak to me as ur e ove r laps wi th other peak when i rra d ia t e d sa mpl e contains nuclides th a t als o e mit s ga mm

  Introduction Neutron Activation An a l y sis (N AA ) i s a nu c le a r analytical technique for quantitati ve multi-element anal y sis . Th e prin c ipl e of NAA is to transform stabl e nu c lide s into radionu c lides b y nu c lear rea ction . This nuclear reaction is induced b y the incident neutron . After the irradi a tion , the characteristic gamma ra y s e mitted b y the radionuclides are quantita v el y measured b y gamma spectroscop y. At present , NAA is done automatically using a computer assisted gamma-ra y spectrometer and high performance Ge detector . Sometimes radiochemical treatment i s n eces sar y f or some reasons :

  6 4 , As-74 , As-76 , Sb-l22 , Na-24 .

  3 2 , 1-133 , Ce-144 , Ce-141 , Sc-4 7 , T e -1 32 , H g -20 3, Au-198 , Ru-10 3 , C u-

  2 9 ± 1 . 76 ppm . Beberapa unsur y an g terkandun g d i d a lam kulit k e r a ng Ohas ar i a d a l a h Ta-1 82 , Pt-197 , 1-131 , 1-1

  2 9 ppm , sedangkan konsentrasi Cu be 17 .

  144 , Ce-141 , Sc-47 , T e -1 32, H g - 203 , Au-1 98 , Ru-1 03, Cu-64 , As-74 , As-76 , Sb-122 , Na-24. Abstract

Determination of Sodium and Copper in Ohasari Sea Shell By Radiochemical Neutron

Activation Analysis . Telah dil a kuk a n pengukuran Sodium dan Tembaga dalam kulit kerang

jenis Ohasari dengan m e n gg un a k a n NAA dan radiokimi a. Ditemukan bahwa konsentrasi Na d a lam kerang 4745 . 00 ± 119 .

  76 ppm . Ohasari s h e ll c ont a in s s om e e lem e nt s s u c h as Ta-18 2 , Pt-l97 , 1-131 , 1-132 , 1-133 , Ce-

  29 ± 1 .

  ± 119 . 29 ppm . T h e co n ce nt ra tion of Cu i n Ohas a ri sh e ll i s found to be 17 .

  Abstract

Determination of Sodium and Copper in Ohasari Sea Shell B y Radiochemical Neutron

Activation Analysis . E l e m e nt a l a n a l ys i s o f So dium a nd C opper in Ohas a ri sea shell has been

performed b y radioch e m ical N AA . Th e co n cent r a tion of Na in Oh asa ri shell is found to be

4745.00

  4Na f rom the sa mpl e in order to get a reliable r es ult for M C U .

• In this experiment , a com p arative method i s utili z ed to defin e th e concentration of the sample . Comp a r a ti ve m e th o d is a method in which an unkno w n sa mpl e is compared to the amount and the count rate of an identical

• ++ +Zn (solid ) ~ C u (s ol i d ) + Zn

  50 W i n frared lamp

  5. Dr y the filter p a p er unde r a 2

  50 J . ll of the solut io n w ith a micro-pipetter a nd pu t it onto 2 5 mm o filter paper

  Sodium standard sample is p r e p a r e d a s the following : 1 . Weigh purified so d iu m c h l oride w hich is equivalent to 0.25 g o f sodium and place it into a 500 ml g l a ss beaker . Put 200 ml of p u r ifi ed wa ter into the same beakar and d iss o lve it . 2 . Transfer the sodium c hloride solution into a 250 ml v olumet r ic flask and adjust the solution to t he 250 m I line of the flask with purifie d wa t e r . 3 . Transfer the sodium s a lt solut i on i nto a gl a ss bottle marked as " 1000 ppm N a " 4 . Take

  The objecti v e of this ex p eri m e n t i s to a n aly z e Na and Cu in the O h a s a r i Sea Shell b y incorporating r a dioche mi ca l se par a tion into NAA

  5 sea she l l , f irstly the irr a diatied th e stan d ard d eviation of th e stand a rd . a x and c , are given as f oll ows : or where N , and N o are the c ounts for the sample and the st a ndard res p e ct ive l y, while t x and t o is the measuring time for the sampl e and the standard , n , an d f i e are the counts rates for the sample a nd the stan d a r d.

  Wid ya nuklid a V ol . 4 . No . I-2 2001: 11-1

  Standard deviation Standard deviation for conce n tr a t i o n ob tained in the comparati v e method i s calculate d as the following : . where C is the calculated con ce n trati o n, a x is the standard de v iation of the s a mple and a o is

  This method is quite simple and gi v e s a reliable result . Cumul a ti v e errors can b e minimized because there are fe w er facto rs involved in the calculation or a n a l ysis .

  W x and W a r e th e am ount o f t he u n kn o wn element and th e s tand a rd r es pe c t ive l y , whi l e n , and fi e are the counting rate s fro m t h e unknown element and the st a nd a rd .

  Simple manipul a tion o f the a b ove e qu a t i o n leads to the equation b e lo w , w , _ w _{_ .}

  _{_ x _} n n

  e lement which i s us e d as st a nd a rd . F or t h is purpose , both the s a mpl e a nd th e s t a nd a r d a re irradiated under th e sa me irr a diation condition . The quantit y o f e a ch e l eme nt i n t h e sample is shown b y th e b e lo w re l ati on s h i p , w = w . _x

  2

  2

  Cu

  2 (gas)

  H

  2

  2W ~ Zn

  In order to g et s olid c opp e r fr om t h e O hasa ri sample is disso lve d in h y d r o ch lori c aci d . I n t o this solution is also a dd e d c upr ic i o n ca r rier and also Zn ribbon wi th 99 . 9% zinc content . The r ea ction ca n b e given as follows : Zn(solid) +

Ex p eriment S t a n dard Sa m ple Pre p a r a tion

  6 . Put the dried filter paper into a plastic bag and then seal the plastic bag with an electric plastic sealer

  Non-destructive analysis of sodium is outlined as the following : 1 . Put 2 rnl of 2M nitric acid, distilled water and ethanol each into 100 rnl beaker separately . Put all 3 beakers on a tra y and then placed in a ventilated draft chamber 2 . Wear rubber gloves . Put the irradiated shell sample into nitric acid and leave it for about

  beaker , add 5 . 00 ml of copper carrier solution (25 mg Cu) using a 5ml volumetric pipette , and place the beaker on a tra y in a draft chamber

  4 M HCl in a 100 ml tall

  5 . Replace the standard sample with the ohasari sample and collect data as was done in Step 4 above . To analyze the concentration of Cu , the same sample used to analyze Na is processed chemically to get solid Cu and to remove all Na. The procedure of radiochemical separation process is outlined as the following : l . Put 20 ml of

  24 Na and read the peak area counts .

  gamma ra y s pectrum for 30 seconds using 4096 channels analyzer (MCA) . Adjust ROI to the photo-peak corresponding to 1 . 369 MeV gamma- ray of

  em from the Ge detector . Collect the

  sample holder at a distance of about 30

  4 . Place the sodium stand a rd sample on a

  a n electronic balance . Write down the sample net weight Ws .

  20 seconds to remove surface contamination by etching . Then using tweezers wash the sample with water and ethanol successively , and dry the shell specimen under an infrared lamp for about 10 minutes . 3 . Put the sample into a plastic tube that is a lread y weighed then weigh it using

  Det e rmin a ti o n of Sodium and Copper .. .

  The above procedure is also implemented for Cu standard . In this case metallic copper is dissolved into nitric acid and then 10 ul of the solution is put onto filter paper . This sample is dried using infrared lamp.

  In the next step , non-destructive analysis (leaching) is performed on the sample and then Na spectrum is measured and then its concentration is calculated . Radiochemical analysis is performed to exclude Na from the samples . In this radiochemical process Cu solid is obtained and its spectrum is analyzed and its concentration is calculated .

  S- I .

  3 ern "

  1

  10

  glass rod , tweezers , spoon , plastic tube , thick paper (5x5 em ) . The procedure of this experiment is outlined as follows . The first step is sampling and sample preparation(including the standard) . The prepared samples are irradiated in JRR-4 with neutron flux of 6 .

  m m o) ,

  In this experiment , the following r e ag e nts a nd apparatuses are needed : Hydrochloric acid (4M HCl) , concentrated nitric acid (RN03) , nitric acid (2M HN03) , copper carrier solution (5 mg C u2+/m l) , ethanol (C2H50H) , metallic z inc ribbon , hot plate , infrared lamp , filtration apparatus , chemical balance , tall beaker (100 ml) , ordinary beaker (100 ml) , plastic beaker (l l . ) , funnel , volumetric pippete (5 ml) , Pi-pump, measuring cylinder (50 ml) , watch glass , filter paper (5C , 9cm~) , glass filter paper (24

  E x p erim en ta l P ro ced u res

  Both the standard sample and the sample to be analyzed are put into a plastic tube and then irradiated simultaneously with neutrons u s ing a pneumatic transfer tube of JRR-3 research reactor at Tokai Research Establishment of JAERI . These samples are irradiated for 2 minut e s .

  2 . Put the irradiated shell sample into the solution . Cover the beaker immediately with a watch glass 3 . After the gas generation ceases , add 1-2 drops of concentrated HN03 to preserve the copper ions in the oxidized form of Cu2 +, then filt e r it wi th 5C 9 e rn e filter paper to r e mo ve a n y insolubl e substances still r e m ai nin g i n th e so l u ti o n .

  Collect the filtrat e i n a

  7 6 ppm . A qualitative anal y sis i s also per f or med to detect elements in the shell . S eve r al sa mp les prepared b y participants of a do m e s t ic training course are also incl u d e d in t h e measurement . The result on th e gam m a spectrum is shown in Figure

  The concentration of C u in Oh a sari shell is found to be 17 .

  29 ± 1 .

  7 6 ppm .

  

Ta bl e 2 Ex p eri m ent d a t a and result for Cu

W,mg count time,s count/s Sta n dard .

  01 2451 ± 49 .

  51

  2 122.

  55 ±2 .

  48 S ampl e 475.7 100 ± 10 . 00 200 0. 50 ±0 . O5 The Table 2 shows the data and the measurement results for Cu concentration in the Ohasari shell . The energ y of Cu tha t is used for calculation i s . 511 MeV and t h e carrier recover y is 49 . 7 % . The c omp a r i so n between sample and the standard resul t s in the value of Cu concentrat i on i n O hasari shell is about 17 .

  29

  ± 1 .

  1 . I t c a n b e known from this sp ec trum th a t th ere a re ma n y 14 3 .

  9 ppm.

  Ohasari shell contains some elements such as Ta-182 , Pt-197, 1-

  1

  3

  1 , 1-1

  3

  2 , 1-

  133, Ce-144, Ce -

  14

  1 , Sc-47 , Te-132 ,

  Hg-203, Au-198 , Ru -

  1 03, Cu - 64 , As-

  74 , As-76, Sb-I22 , Na-2 4 . Reference I . Ko Noguchi, Radi o c h e m i cal Neutron Activation Analysis: Determination of Sodium and Copper in Sea Shell , Lecturing Note ITP 2001 , NuTEC , T o ky o . Acknowledgement The author would like t o ex press his acknowledgement to Dr . Hi ro s hi Ka m i oki , Dr . Kouhei Kushita, Dr . Ko . No g u c h i for their assistance in doing ex p erime nt i n NuTec

  2 .

  9.2

  1 00 ml t a ll b eake r . Discard th e us e d filt e r p a p er .

  1 . The concentrati on o f Na i n Ohasari Ta bl e

  Result and Discussion The energ y that i s u se d t o ana l yse Na in the sample and s tand ar d is

  1 . 369 MeV . The measurement result s a nd t h e d ata to calculate Na concentration in Oh asari s h e l l is s ho wn in Table 1 .

  Widyanuklida Vol .

  4. No . I-2 2001 : 11-1

  5 ele m e n ts in O has ari s hell : Ta-182 , Pt-197 , 1 - 131,1 - 132,1-

  1 33, Ce -144 , Ce-141 , Sc-47 ,

  Te-132 , Hg-203 , A u-198 , Ru-10 3, Cu-64 , As-74 , As-76, S

  b- l22, Na-

  2

  4 . The

  existence of Na-24 i n t h e gamma spectrum shows that the eliminati on process of Na in some samples is not p e rformed well .

  Conclusion The measurement of Na a nd C u in Ohasari shell have been p erf orm e d a nd the following are clarifie d :

  1 Ex p e r i m e n t d ata an d resu l ts for Na

  1

  W , mg count time,s count/s S tand ard .

  5 1933 .

  00

  ±

  43.97

  30 64 . 43 ± 1 .

  47 S ampl e 475 . 7 8727 . 00 ± 93 .

  42 30 290 . 90 ±

  3.11 The comparison betwe e n sam p le and the standard result s in th e value of Na concentration in Oha s ar i s h e ll is about 4745 ±

  11 9 .

  29 p p m . shell is found to be 4745 ±

  1

  Laborator y of JAERl .

  ..

  Det e rmin a t io n o f Sodium and Copper ...

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  76 _{-; 1 .3} m < • • . >

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