- Email: [email protected]
Determination of copper, gallium and zinc in “standard rocks” by neutron activation
172
ANALYTICA
1~E’L’EIWINA’I’ION OF ROCKS” 13Y NEUTI
COPPER, GALLIUM ACTIVATION
.4ND
ZINC
IN
CHI,MICA ACTA
“STANDARD
anillysiS is estremcly lligll for most As the sensitivity of neutron activation elements, it I~as become an important analytical method for establishing the conccntrations of minor and trace clcments in rocks and minerals. By this mcthocl the distribution of copper IlilS been stucliecl in SiunplCS from cosmicl-0, tcrrestriall~7~H and oceanic sourcesi. Gallium IliE heen determinctl by neutron activation in mctcorites(‘-1 1 and silicate rocks1~, while tlic abundance of zinc has been investigated and mill products*“. in metcoritcs~~, igneous rocks 13-15, ores’“*lfl, refractories16 l~aclioclicniicnl separations combined with y-ray scintillation spectromctry can provide sirnplc and sclectivc Ix-ocedurcs for many elements. Often more than one clcmcnt can easily Ix dctermincd in tlic same sample without any essential increase determination of copper, in work. In this report a method for the simultaneous gallium nncl zinc in silicate rocks by neutron activation analysis is presented. The samples cl~xcn for this work were a series of igneous “stanclarcl rocks” rcccntly clistributccl by the U.S. hological Survey. The series included granite G-2, ncpllclinc syenite S’L’M-I, granoclioritc GSP-I , nndesite AGV-I , basalt 13CR-I, periclotite KC-I and tlunite DTS-I. As a supplement a tonalite labelled T-I, issued from the Geological Survey of Tanganyika, was also analysecl. In aclclition, to check tllc iUKdyticL11 inctliod, tlic estcnsivcly analysccl cliabase W-x was investigated. Tlic nuclear data for the rclcvant activation reactions for copper, gallium and
zinc are given in Table
I. Samples
ancl standards
were
irradiated
for 24 11 in the
-..-_ Cu
c.a Zn
rlclivr1liotr
Cross-s&ion
mrcf
(bnrus)
io9b
of
-_-_--.-_“:‘cu
(11 ,y)
“Gl
* Positron anniliihtion. .dmd. c/&u.
i Id/-ltfe
nctn,
37 (1967) 172-178
12.8
-1.4
4.6 -
0.10
._-
y-cucrgy
rccclio-
uticlide
7Gn(n,y)7Gn “%n(n,y)aoln%n
..
--
-__---
lSlcnrt!nt
‘4.3 13.8
rrsed (ir)
(Me
V)
0.51’L 0.84 0.43
CU,G~AND
Zn
IN
I73
IZOCKS
*JEEP I reactor (Kjeller, Norway) at a thermal neutron flus of about 2. xole n/cme sec. The irradiated rock specimens were decomposed by alkaline fusion. The cooled melt was dissolved in water and the chloride concentration was adjusted to G M with concentrated hydrochloric acid. Copper, gallium and zinc were adsorbed from this solution on a strongly basic anion-eschange resini’. Copper and gallium were elutcd in one portion with 0.5 N hydrochloric acid, while zinc was subsequently cluted with s’j/o ammonia solution. The chemical yield was determined by a reactivation technique after the activities of interest had $ecayed away. Generally the chemical yield obtained was in the range Go-So ‘)$ for each of the elements. The tecliniclue of m-activation is convenient to use in analyses of extensive series of geological samples. I3esides its simplicity, the technique also often allows the simultaneous determination of more than one element in one fraction. This method could generally he used more extensively in chemical yield determinations, The y-spectrum of an eluate containing copper and gallium is shown in Fig. I. The two smaller peaks at x.10 MeV and 1.3~~MeV are due to 45-d 5UI;e formed by neutron capture in iron present in the samples. However, in most cases these peaks did not disturb seriously the determination of copper and gallium by the 0.51 McV
01
13 Enerqv
Fig.
I. y-Spectrum
Pig.
2.
of cluntc of copper
y-SI>tXtril
02 Energy
Fig.
3. y-Spectrum
.a!5
(fLrJ)
contnining
10 Energy
---_
(MOVI
colqwr anti gnlliunl.
nntl gnlliun1 stnndarcts.
a4
of cluatc
containing
zinc.
and o.S4 MeV peaks respectively. In Fig. 2 y-spectra of copper and gallium standards are shown. A y-spectrum of an eluted zinc fraction is shown in Fig. 3. Spectra of zinc standards and zinc eluates were quite identical in shape. The peak areas were evaluated by the method of COVELL’~. Awd.
China. Ada.
37
(1967)
172-I
78
‘I’llc y-activities were Incasurctl wit]I iLIl “Intertccl~nicluc” an;dysc!r M-40 wit11 I well-type -3 x 3” h’;ll(‘l’l) crysh].
‘Fill a cc~lutJirJ c~l~loridc
form)
C:uvvkv
to
8
of iiitcrnd
CIII
llcigllt
sol~~1iorr.s.
c]i]oI*ic]c ;IJIC] zinc
I)issc)lvc
(~11loritlc
diaJnctcr
of resin
bctl.
in
col.rc!sl’c)ncling
<) mm
witli
l’rctccluilil~ratc
wktcr to
I~0wc.u wit11
illll~~UJltS of cu.
5 Iiig
Cu/nll,
2-M 0
400-clIanrIc]
(xw_b_3cm
n~esli,
N IIyclrocl~loric
c:r>pJwr cliloritlc, 2 nig
(;a/!111
acid.
gnllium and
5 17ig
%rl/Illl. .Sluntirud .S(J/l/!i//ll.S. Dissolve mXXIr;ltcly \wigllctJ ;urIounts Of co])pcr IllC!tiLl iJ3 iicicl, ~~tlliurn cJsi(li! in sulpl~uric :icid arltl zinc Inetzil in IIytlroclIloric ilCiC1. Dilute witli water to snitul~lc c~)nccntrntions. ‘I’lic following: conccIItr;itioIls arc rccollllllcnC~ccl: c.yU, 5 l).]>.llI.; (;;L, 2 ]I.p.lll.; %ll, 50 J’.JIlll.
Ilitric
Wcigll cn. I00 IJI~ of tllc rock lmwtlcr ;mamtcly into polyctllylcnc vials of cliatnctcr illl(l I~!ll~tll. (‘IOSC witli il StO]~]K!V. Seal about x .3 1111of the stantlarcl solutions of coJ3Jwr, g;dliuIn ant1 zinc selmratdy ilIt c]lI:irtz ;i~~~Jmulcs, I’I;Lcc tllc s;unJ~1cs ant1 stan~hrcls as dose to cx31 otlic~ as J)ossil)lc in an alutniniuni c:ontaincI and irrxliatc at a tlicrrnal neutron flus of il13OUt 2 * IoIz Ji/cIli~s~x for zii II. Slll~lll
Allow tlic irrudiatctl s:uiiJ~lc to cool for 24 II COJ* tJ\c clccay of slIort-lived activi tics, niainly 2..56-1 I “%Jn. Pipcttc csactly I.OO nil of cnclI carrier solution of co]~J~cr, pilliuni ancl zinc: into ;L nickel c:ruc:il,lc iklItl cvapolxtc carefully to dryness llJlClW il Iicating lillll]‘. l’our tllc s;tniJ)lc into tlw crucible, and add 2 g of sodium liydrositlc Jx2JJct.S. J-lent tllc cniciblc o\*cr iL Mcl;c!r I)iwner for 5 min.it:itc. WaslI tlIc resin twice \vitll .5 1111nf 0 N IIvclroclIloric acicl. Diw;~rtl tlm cfflucnt. E]UtC COJ>l’CJ and @llliUlll witll I0 1111 of (j.5 - h 1 l~ydrr~cl~loric acicl and collect tllc cluatc in a =$)-ml ~~~JyctlIylcnc %rcwcnJ> bottle. Was11 twice witli 10 ml of 0.5 N Iiyclrocliloric ncicl. Diswrcl tlic cfflucnt. Finally clutc tllc zinc \vitlI IO 1111of ;I syi, ~JTllll~~lliil solution illltl again cc~llcct tllc ClLlntc in ;\ 50-1111 J~o1yctllylcI~e scl-cwc%J~ Imttlc.
Pipcttc 1.00 1111of each stahdarcl solution from the quarter, ani~mulees and trnnsfer to separntc so-1111 J~olyethylene scrcwcap bottles. Dilute to x0 In1 with water to obtain the sanic counting gmmetry as for the clutecl fractions. A ,rnl. Clbh.
.4cln,
37
(1907)
17’-17s
Cu, Ga Activity
AND
Zn IN ROCKS
175
nteaswentents
Record the y-spectra for the samples and standards with a multiclxmnel analyser. Evaluate the area under tile peaks of interest corresponding to tllc yenergies listed in Table I. Repeat the rccorcling of the spectra after s-15 11 to check tlic disintegration rates.
Allow the activities of WL, ‘%a and cJo’Un to decay for one week. Dilute tile fraction contnining copper ancl gallium to a50 ml with distillecl water. Similarly dilute the zinc eluatc to 50 ml. Seal about I.2 ml of encll solution separately into polyetl~ylcnc tubes and :lctivatc for x 11togctller wit11 aliquots of the carrier solutions at tllerIlla1 neutron flus Of alx:mt Z-10*2 n/cm’/sec. diluted in tile same nlanncr. allow the solutions to “cool” for 3-4 11. Pipette 1.00 ml After the irradiation, of txc11 solution into separate pc~lyctliylcnc vials and rii&ure tlw activity as clcscril~eci almvC. i1
The results oMainet1 for coplwr, g’alliunl illlcl zinc in tllc geoclwrnical rock stxnclarcls analysecl in tll is work are lwescntcd in ‘l’al>lc II, togctllcr wit11 tllc mean value for ewli element. In Table III tlw mean values obtained for tile copper, gallium and zinc content in standnrd clir~lmsc W-r are comlxiretl wit11 tlic rccomnienclcd values quoted in tlw recent coml~ilntion of clatx 011 W-x given by L~I.mscxi151~~~~, and also wit11 ~lVilil~l~1~ values of other workers using mutt-on activation ;mdysis. ‘I’lw results of tllc prcscnt work m-c in good agrccnicnt wit11 previously rcportecl activation results. Howcvcr, tlie data ol>tainccl by neutron activation are slightly liiglicr than the rcconimcndccl values. G-2 is intended to be a replaccnwnt of tllc now nearly cxlmusted G-I. Tile
cu -Av.
tia
Av.
G.G s-4
6.1 5.8 8.2
4’
I23
2.0
31
41 39
III
113
I.9 2.1
35 32
48 54 53
I2 13 14
G.7
40
I IG
2.0
33
52
13
9.0
G.1
20 21 22
2.3 20 23
1.2 I.3 1.4
I.2 1.G
21
24
I*3
I.3
22
19
19
I9
36
27 2.t
21
20
19
33;:
25 24 23
20
38
24
24
19
c; I’.‘)
0.2
1.0
%n 71 76 85
I02
84
1’5
4 ’
‘73
87 83 80
204
I60
206
218
105 1x7
85 92
IIG 114
42 43
G4 56 G2
A\?. 77
IGCJ
83
209
108
87
1’5
42
GI
175
-_ Awd.
Clriva.
Acta,
37 (1967)
172-178
results ol,tainecl for G-2 sl10w fairly good agrcemcnt wit11 tire recommended valucs~~~ for G-I on copper and gallium (respectively 13 p.p.m. and 18 p.p.m,). However, the lower than the present rcccm~n~endcd value of zinc in G-x, 45 p.p.m., is considcra,biy result for G-2. A significant differcncc Ixtwcen other trace element contents of G-I rtncl the replacement G-2 has also Ix33 establislicd prcviously26.‘fi.
aml*.4l~lsoN
cm
hC’rlvi\‘rloN
1~1isu1:1‘.s
I~I~ICSISN~T
..____________
__-._-.-.
1msu1.75 ..._._
IZOI<
----
W-r
cu
116
110
Gil
-lo
%n
--
83
.-- --
I’IIISSILN’I’
-_--
IlI%UL’rS
-.._
I’OH
ilcfereme
112’
,
18.3’V,
82
85’3,
82.81,’
‘r-1
~
ANI)
SUIII~~~
COMl’Al
\VITII -.
NB~TI
of values
rcportcd
As can Ix seen from tonalite T-I and previous rock is satisfactory.
DATA
(1’.1’.1n.)
._P-I.--___-_ Clb
CU
.T~~b
Gz
Spcctrochcmical
by scvcrnl
I’UIILISlllil~
--____.-.
and
spcctrogr;~phic
fluorcsccncc Neutron activation
worlc
I lb”’
,G.g’lU
I’IIlS\‘IoUS
S-ray
LiAYXa,
1’ lhngc
i’ilI:v~ous
-._ _--.-- -.--.--..----.-.-..
__.. -
Clicmic:d
1107
1202”,
18’2,
IWl~lhd
‘~IIOMAS3~ This
AND
-___-_--__.-
I G
._._._...
‘rON,\I.I’~IC
- ______
_-.-_-__--
~NGAhYlXLS
-.--
vhr.uiisI~
f’rcvio~isly plc/dislrcrl uelclron (1~l(!ul1 fJ*p.r,l.) zJal11c.s’~ rictivcif iou dcilu (*./Ar,l.) (/A/Lr,r.) .-_.___.__. ______ -__. - ..___._ --._- ._-_ -_..--._-_ _....- ..___-_____ Iteconin~cndd
-___--.-
r~Ixz0~Inl1~s~1~1~
- .-----
_...
J’Yc*sl~ I1I ItJO VI<
i.lo,rc~rll
wrrll
40-55’ 45 40
IGO
x7-25”
IGO-220”
19
rgB 169
-
---
workers.
Table IV, the agreement published data for copper,
bctwecn the prcscnt results of gallium and zinc in this standard
Precisio~rL ad accwacy From Table II it can 1x2 seen that the average pt-ccision for the determination of copper, gallium and zinc by the present method is about 3_ sty0 for concentrations escccding IO p.p.m. The results were obtained by rcpcatccl runs on duplicate samples of each rock. No systematic errors due to flus inhomogeneity within the irradiation unit are therefore likely to influence the mean values. On the other hand, the accuracy may be considerably affected by shielding effects in samples or stnnclarcls either in the primary activation or in the chemical yield determination. However, as none of the major constituents of the rock samples arc strong neutron absorbers, and as dilute solutions of the elements were used as standards, such effects can bc neglected. Serious systematic errors may occur clue to interfering nuclear reactions induced by fast neutrons, In the present work f%n(n,p)s*ICu is the only fast neutron rcnction which can result in significant interference. In the cast of nepheline syenite STM-I where the ratio Zn :Cu is about 200, the correction due to the contribution from the (n,p)-reaction amounts to approsimately 5:/o_ For the other standards the R?ictl. Chirn. Acta, 37 (1907)
x72-178
Cu,
Ga AND
&IN
ROCKS
177
as the interference is negligible. Interfcrcncc from fission of 23JI-J is also negligible, fission yields of the elements analysecl arc known to be cstremely small. On the basis of tlx discussion above and of the good agreement between the present results and recommcnclecl values for W-x, it seems reasonable that the mean values reported in this work are accurate to about j-5’;: when the concentration of the actual elements exceeds IO p.p.rn.
The sensitivity of the present method for the determination of copper and gallium depends on the respective amounts of gallium and iron present (cf. Fig. I). Usually the limit of sensitivity is of the order of 0.5 Jxp.m. for both eletnents. If required. far better sensitivity can be acllievcd by introducing additional separation steps. The sensitivity of the zinc determination depends on the weight of sample and the neutron flus employed. With roe-mg samples and a neutron flux of 2 * x0*" n/cm%ec tlic limit of sensitivity is about 0.4 1xp.m. The mcthocl described is simple and sufficiently sensitive for the general cletermination of copper, gallium and zinc in igneous rocks. The mcthocl should be attractive for studies of fractionation processes of tllese elements within igneous rock systems. This work was cnrriecl out wllile one of the authors (A.O.B.) held a research fclJowshipgrnnte
A neutron activation method for the simultaneous gallium and zinc in rocks is clescribed. The metllocl is seJ>aration steJx and measurement of y-activity. Clwmical rc-activation. Results for a series of igneous “standarcl accuracy of the mean values is ca. sy’/o for cc,nc.c:ntrations
clctermination of copper, based on anion-eschange yields were determined by rocks” arc prcsentcd. The escecding I0 p.p.m.
On d4crit une m&hode par activation au tnoyen de neutrons pour le dosage simultan@ du cuivre, du gallium et du zinc dans des roches. Elle cst basde sur des sdparations ,2 l’aidc d’&hangeur d’anions et mesurc de l’activitc! y. Des rhultnts sont donnh pour des &zhantillons standards. La pr6cision des valeurs moyennes est d’environ dc sf/o pour dcs concentrations dc5passant IO p.p.m. ZUSAMXIISNI'ASSUNC
Es wird die gleiciizeitige I3estimmung von Kupfer, Gallium und %inJc in Gcsteinen mit der Neutronenaktivierungsanalyse bescllrieben. Das Verfahren verwendet zur Trennung Anionenaustauscher und die IvIessung dcr y-Aktivitiit. Die chemischen Ausbeuten wurden durch Reaktivierung bestimmt. Es wcrden Ergebnisse Die Genauigkeit der Mittelwerte betr:igt einer Reille von Beispielen angegeben. etwa 50/t:,bei Konzentrationen von mehr als IO p.p.m.
178
1 2
3 ‘I 5 fi 7 8 ‘3
IO IL 12 ‘3 ‘4
1.5 I0
‘7
18 I0 20
A. 0.
BRUNI:EJ.‘I’,
0.
JOHANSEN,
IS. STEINNES
ANALYTICA
1~E’L’EIWINA’I’ION OF ROCKS” 13Y NEUTI
COPPER, GALLIUM ACTIVATION
.4ND
ZINC
IN
CHI,MICA ACTA
“STANDARD
anillysiS is estremcly lligll for most As the sensitivity of neutron activation elements, it I~as become an important analytical method for establishing the conccntrations of minor and trace clcments in rocks and minerals. By this mcthocl the distribution of copper IlilS been stucliecl in SiunplCS from cosmicl-0, tcrrestriall~7~H and oceanic sourcesi. Gallium IliE heen determinctl by neutron activation in mctcorites(‘-1 1 and silicate rocks1~, while tlic abundance of zinc has been investigated and mill products*“. in metcoritcs~~, igneous rocks 13-15, ores’“*lfl, refractories16 l~aclioclicniicnl separations combined with y-ray scintillation spectromctry can provide sirnplc and sclectivc Ix-ocedurcs for many elements. Often more than one clcmcnt can easily Ix dctermincd in tlic same sample without any essential increase determination of copper, in work. In this report a method for the simultaneous gallium nncl zinc in silicate rocks by neutron activation analysis is presented. The samples cl~xcn for this work were a series of igneous “stanclarcl rocks” rcccntly clistributccl by the U.S. hological Survey. The series included granite G-2, ncpllclinc syenite S’L’M-I, granoclioritc GSP-I , nndesite AGV-I , basalt 13CR-I, periclotite KC-I and tlunite DTS-I. As a supplement a tonalite labelled T-I, issued from the Geological Survey of Tanganyika, was also analysecl. In aclclition, to check tllc iUKdyticL11 inctliod, tlic estcnsivcly analysccl cliabase W-x was investigated. Tlic nuclear data for the rclcvant activation reactions for copper, gallium and
zinc are given in Table
I. Samples
ancl standards
were
irradiated
for 24 11 in the
-..-_ Cu
c.a Zn
rlclivr1liotr
Cross-s&ion
mrcf
(bnrus)
io9b
of
-_-_--.-_“:‘cu
(11 ,y)
“Gl
* Positron anniliihtion. .dmd. c/&u.
i Id/-ltfe
nctn,
37 (1967) 172-178
12.8
-1.4
4.6 -
0.10
._-
y-cucrgy
rccclio-
uticlide
7Gn(n,y)7Gn “%n(n,y)aoln%n
..
--
-__---
lSlcnrt!nt
‘4.3 13.8
rrsed (ir)
(Me
V)
0.51’L 0.84 0.43
CU,G~AND
Zn
IN
I73
IZOCKS
*JEEP I reactor (Kjeller, Norway) at a thermal neutron flus of about 2. xole n/cme sec. The irradiated rock specimens were decomposed by alkaline fusion. The cooled melt was dissolved in water and the chloride concentration was adjusted to G M with concentrated hydrochloric acid. Copper, gallium and zinc were adsorbed from this solution on a strongly basic anion-eschange resini’. Copper and gallium were elutcd in one portion with 0.5 N hydrochloric acid, while zinc was subsequently cluted with s’j/o ammonia solution. The chemical yield was determined by a reactivation technique after the activities of interest had $ecayed away. Generally the chemical yield obtained was in the range Go-So ‘)$ for each of the elements. The tecliniclue of m-activation is convenient to use in analyses of extensive series of geological samples. I3esides its simplicity, the technique also often allows the simultaneous determination of more than one element in one fraction. This method could generally he used more extensively in chemical yield determinations, The y-spectrum of an eluate containing copper and gallium is shown in Fig. I. The two smaller peaks at x.10 MeV and 1.3~~MeV are due to 45-d 5UI;e formed by neutron capture in iron present in the samples. However, in most cases these peaks did not disturb seriously the determination of copper and gallium by the 0.51 McV
01
13 Enerqv
Fig.
I. y-Spectrum
Pig.
2.
of cluntc of copper
y-SI>tXtril
02 Energy
Fig.
3. y-Spectrum
.a!5
(fLrJ)
contnining
10 Energy
---_
(MOVI
colqwr anti gnlliunl.
nntl gnlliun1 stnndarcts.
a4
of cluatc
containing
zinc.
and o.S4 MeV peaks respectively. In Fig. 2 y-spectra of copper and gallium standards are shown. A y-spectrum of an eluted zinc fraction is shown in Fig. 3. Spectra of zinc standards and zinc eluates were quite identical in shape. The peak areas were evaluated by the method of COVELL’~. Awd.
China. Ada.
37
(1967)
172-I
78
‘I’llc y-activities were Incasurctl wit]I iLIl “Intertccl~nicluc” an;dysc!r M-40 wit11 I well-type -3 x 3” h’;ll(‘l’l) crysh].
‘Fill a cc~lutJirJ c~l~loridc
form)
C:uvvkv
to
8
of iiitcrnd
CIII
llcigllt
sol~~1iorr.s.
c]i]oI*ic]c ;IJIC] zinc
I)issc)lvc
(~11loritlc
diaJnctcr
of resin
bctl.
in
col.rc!sl’c)ncling
<) mm
witli
l’rctccluilil~ratc
wktcr to
I~0wc.u wit11
illll~~UJltS of cu.
5 Iiig
Cu/nll,
2-M 0
400-clIanrIc]
(xw_b_3cm
n~esli,
N IIyclrocl~loric
c:r>pJwr cliloritlc, 2 nig
(;a/!111
acid.
gnllium and
5 17ig
%rl/Illl. .Sluntirud .S(J/l/!i//ll.S. Dissolve mXXIr;ltcly \wigllctJ ;urIounts Of co])pcr IllC!tiLl iJ3 iicicl, ~~tlliurn cJsi(li! in sulpl~uric :icid arltl zinc Inetzil in IIytlroclIloric ilCiC1. Dilute witli water to snitul~lc c~)nccntrntions. ‘I’lic following: conccIItr;itioIls arc rccollllllcnC~ccl: c.yU, 5 l).]>.llI.; (;;L, 2 ]I.p.lll.; %ll, 50 J’.JIlll.
Ilitric
Wcigll cn. I00 IJI~ of tllc rock lmwtlcr ;mamtcly into polyctllylcnc vials of cliatnctcr illl(l I~!ll~tll. (‘IOSC witli il StO]~]K!V. Seal about x .3 1111of the stantlarcl solutions of coJ3Jwr, g;dliuIn ant1 zinc selmratdy ilIt c]lI:irtz ;i~~~Jmulcs, I’I;Lcc tllc s;unJ~1cs ant1 stan~hrcls as dose to cx31 otlic~ as J)ossil)lc in an alutniniuni c:ontaincI and irrxliatc at a tlicrrnal neutron flus of il13OUt 2 * IoIz Ji/cIli~s~x for zii II. Slll~lll
Allow tlic irrudiatctl s:uiiJ~lc to cool for 24 II COJ* tJ\c clccay of slIort-lived activi tics, niainly 2..56-1 I “%Jn. Pipcttc csactly I.OO nil of cnclI carrier solution of co]~J~cr, pilliuni ancl zinc: into ;L nickel c:ruc:il,lc iklItl cvapolxtc carefully to dryness llJlClW il Iicating lillll]‘. l’our tllc s;tniJ)lc into tlw crucible, and add 2 g of sodium liydrositlc Jx2JJct.S. J-lent tllc cniciblc o\*cr iL Mcl;c!r I)iwner for 5 min.
Pipcttc 1.00 1111of each stahdarcl solution from the quarter, ani~mulees and trnnsfer to separntc so-1111 J~olyethylene scrcwcap bottles. Dilute to x0 In1 with water to obtain the sanic counting gmmetry as for the clutecl fractions. A ,rnl. Clbh.
.4cln,
37
(1907)
17’-17s
Cu, Ga Activity
AND
Zn IN ROCKS
175
nteaswentents
Record the y-spectra for the samples and standards with a multiclxmnel analyser. Evaluate the area under tile peaks of interest corresponding to tllc yenergies listed in Table I. Repeat the rccorcling of the spectra after s-15 11 to check tlic disintegration rates.
Allow the activities of WL, ‘%a and cJo’Un to decay for one week. Dilute tile fraction contnining copper ancl gallium to a50 ml with distillecl water. Similarly dilute the zinc eluatc to 50 ml. Seal about I.2 ml of encll solution separately into polyetl~ylcnc tubes and :lctivatc for x 11togctller wit11 aliquots of the carrier solutions at tllerIlla1 neutron flus Of alx:mt Z-10*2 n/cm’/sec. diluted in tile same nlanncr. allow the solutions to “cool” for 3-4 11. Pipette 1.00 ml After the irradiation, of txc11 solution into separate pc~lyctliylcnc vials and rii&ure tlw activity as clcscril~eci almvC. i1
The results oMainet1 for coplwr, g’alliunl illlcl zinc in tllc geoclwrnical rock stxnclarcls analysecl in tll is work are lwescntcd in ‘l’al>lc II, togctllcr wit11 tllc mean value for ewli element. In Table III tlw mean values obtained for tile copper, gallium and zinc content in standnrd clir~lmsc W-r are comlxiretl wit11 tlic rccomnienclcd values quoted in tlw recent coml~ilntion of clatx 011 W-x given by L~I.mscxi151~~~~, and also wit11 ~lVilil~l~1~ values of other workers using mutt-on activation ;mdysis. ‘I’lw results of tllc prcscnt work m-c in good agrccnicnt wit11 previously rcportecl activation results. Howcvcr, tlie data ol>tainccl by neutron activation are slightly liiglicr than the rcconimcndccl values. G-2 is intended to be a replaccnwnt of tllc now nearly cxlmusted G-I. Tile
cu -Av.
tia
Av.
G.G s-4
6.1 5.8 8.2
4’
I23
2.0
31
41 39
III
113
I.9 2.1
35 32
48 54 53
I2 13 14
G.7
40
I IG
2.0
33
52
13
9.0
G.1
20 21 22
2.3 20 23
1.2 I.3 1.4
I.2 1.G
21
24
I*3
I.3
22
19
19
I9
36
27 2.t
21
20
19
33;:
25 24 23
20
38
24
24
19
c; I’.‘)
0.2
1.0
%n 71 76 85
I02
84
1’5
4 ’
‘73
87 83 80
204
I60
206
218
105 1x7
85 92
IIG 114
42 43
G4 56 G2
A\?. 77
IGCJ
83
209
108
87
1’5
42
GI
175
-_ Awd.
Clriva.
Acta,
37 (1967)
172-178
results ol,tainecl for G-2 sl10w fairly good agrcemcnt wit11 tire recommended valucs~~~ for G-I on copper and gallium (respectively 13 p.p.m. and 18 p.p.m,). However, the lower than the present rcccm~n~endcd value of zinc in G-x, 45 p.p.m., is considcra,biy result for G-2. A significant differcncc Ixtwcen other trace element contents of G-I rtncl the replacement G-2 has also Ix33 establislicd prcviously26.‘fi.
aml*.4l~lsoN
cm
hC’rlvi\‘rloN
1~1isu1:1‘.s
I~I~ICSISN~T
..____________
__-._-.-.
1msu1.75 ..._._
IZOI<
----
W-r
cu
116
110
Gil
-lo
%n
--
83
.-- --
I’IIISSILN’I’
-_--
IlI%UL’rS
-.._
I’OH
ilcfereme
112’
,
18.3’V,
82
85’3,
82.81,’
‘r-1
~
ANI)
SUIII~~~
COMl’Al
\VITII -.
NB~TI
of values
rcportcd
As can Ix seen from tonalite T-I and previous rock is satisfactory.
DATA
(1’.1’.1n.)
._P-I.--___-_ Clb
CU
.T~~b
Gz
Spcctrochcmical
by scvcrnl
I’UIILISlllil~
--____.-.
and
spcctrogr;~phic
fluorcsccncc Neutron activation
worlc
I lb”’
,G.g’lU
I’IIlS\‘IoUS
S-ray
LiAYXa,
1’ lhngc
i’ilI:v~ous
-._ _--.-- -.--.--..----.-.-..
__.. -
Clicmic:d
1107
1202”,
18’2,
IWl~lhd
‘~IIOMAS3~ This
AND
-___-_--__.-
I G
._._._...
‘rON,\I.I’~IC
- ______
_-.-_-__--
~NGAhYlXLS
-.--
vhr.uiisI~
f’rcvio~isly plc/dislrcrl uelclron (1~l(!ul1 fJ*p.r,l.) zJal11c.s’~ rictivcif iou dcilu (*./Ar,l.) (/A/Lr,r.) .-_.___.__. ______ -__. - ..___._ --._- ._-_ -_..--._-_ _....- ..___-_____ Iteconin~cndd
-___--.-
r~Ixz0~Inl1~s~1~1~
- .-----
_...
J’Yc*sl~ I1I ItJO VI<
i.lo,rc~rll
wrrll
40-55’ 45 40
IGO
x7-25”
IGO-220”
19
rgB 169
-
---
workers.
Table IV, the agreement published data for copper,
bctwecn the prcscnt results of gallium and zinc in this standard
Precisio~rL ad accwacy From Table II it can 1x2 seen that the average pt-ccision for the determination of copper, gallium and zinc by the present method is about 3_ sty0 for concentrations escccding IO p.p.m. The results were obtained by rcpcatccl runs on duplicate samples of each rock. No systematic errors due to flus inhomogeneity within the irradiation unit are therefore likely to influence the mean values. On the other hand, the accuracy may be considerably affected by shielding effects in samples or stnnclarcls either in the primary activation or in the chemical yield determination. However, as none of the major constituents of the rock samples arc strong neutron absorbers, and as dilute solutions of the elements were used as standards, such effects can bc neglected. Serious systematic errors may occur clue to interfering nuclear reactions induced by fast neutrons, In the present work f%n(n,p)s*ICu is the only fast neutron rcnction which can result in significant interference. In the cast of nepheline syenite STM-I where the ratio Zn :Cu is about 200, the correction due to the contribution from the (n,p)-reaction amounts to approsimately 5:/o_ For the other standards the R?ictl. Chirn. Acta, 37 (1907)
x72-178
Cu,
Ga AND
&IN
ROCKS
177
as the interference is negligible. Interfcrcncc from fission of 23JI-J is also negligible, fission yields of the elements analysecl arc known to be cstremely small. On the basis of tlx discussion above and of the good agreement between the present results and recommcnclecl values for W-x, it seems reasonable that the mean values reported in this work are accurate to about j-5’;: when the concentration of the actual elements exceeds IO p.p.rn.
The sensitivity of the present method for the determination of copper and gallium depends on the respective amounts of gallium and iron present (cf. Fig. I). Usually the limit of sensitivity is of the order of 0.5 Jxp.m. for both eletnents. If required. far better sensitivity can be acllievcd by introducing additional separation steps. The sensitivity of the zinc determination depends on the weight of sample and the neutron flus employed. With roe-mg samples and a neutron flux of 2 * x0*" n/cm%ec tlic limit of sensitivity is about 0.4 1xp.m. The mcthocl described is simple and sufficiently sensitive for the general cletermination of copper, gallium and zinc in igneous rocks. The mcthocl should be attractive for studies of fractionation processes of tllese elements within igneous rock systems. This work was cnrriecl out wllile one of the authors (A.O.B.) held a research fclJowshipgrnnte
A neutron activation method for the simultaneous gallium and zinc in rocks is clescribed. The metllocl is seJ>aration steJx and measurement of y-activity. Clwmical rc-activation. Results for a series of igneous “standarcl accuracy of the mean values is ca. sy’/o for cc,nc.c:ntrations
clctermination of copper, based on anion-eschange yields were determined by rocks” arc prcsentcd. The escecding I0 p.p.m.
On d4crit une m&hode par activation au tnoyen de neutrons pour le dosage simultan@ du cuivre, du gallium et du zinc dans des roches. Elle cst basde sur des sdparations ,2 l’aidc d’&hangeur d’anions et mesurc de l’activitc! y. Des rhultnts sont donnh pour des &zhantillons standards. La pr6cision des valeurs moyennes est d’environ dc sf/o pour dcs concentrations dc5passant IO p.p.m. ZUSAMXIISNI'ASSUNC
Es wird die gleiciizeitige I3estimmung von Kupfer, Gallium und %inJc in Gcsteinen mit der Neutronenaktivierungsanalyse bescllrieben. Das Verfahren verwendet zur Trennung Anionenaustauscher und die IvIessung dcr y-Aktivitiit. Die chemischen Ausbeuten wurden durch Reaktivierung bestimmt. Es wcrden Ergebnisse Die Genauigkeit der Mittelwerte betr:igt einer Reille von Beispielen angegeben. etwa 50/t:,bei Konzentrationen von mehr als IO p.p.m.
178
1 2
3 ‘I 5 fi 7 8 ‘3
IO IL 12 ‘3 ‘4
1.5 I0
‘7
18 I0 20
A. 0.
BRUNI:EJ.‘I’,
0.
JOHANSEN,
IS. STEINNES