fission yield of to obtain the total fissions. The precision and accuracy of the method are limited by counting statistics which, of course, are propresent. portional to the amount of Samples containing 0.001 p g . of IiZ9can be detected (using a 2-hour irradiation) with a precision of about 10%. Extraneous activities are eliminated by virtue of the preirradiation carrier chemistry.
fission yield. This value was compared with the total fissions in the sample solution obtained from the more stable fission elements-e.g., Cs13’, Ce144,and Zrg5. This is the ratio referred to as the fraction remainiing. The amount of 1,?36 in each of thje solut,ions was in the 100- to 200-pg. range. The chemical yield of the method utilizing the iodide carrier is indicated in the last column. The sensitivity of this method is a t the nanogram level. Activation of the carrier isotope for yield provides an accurate, convenient, and compatible feature to the method. An uncertainty is introduced when employing t’he
( 2 ) Eastwood, T. A , , Baerg, A. P., Brown,
F., Grunimitt, R. E., Ray, J. C., Ray, L. P., “Radiochemical Measurements of the Neutron Caature Cross Sections of Some Fission Groducts and Protoactinium-233.” T-YCC‘ ( C a n ) 11 (1958).
(3jtGlendenin, L. E., Metcalf, R . P., Improved Determination of Iodine activity in Fission,” paper 278 in “Radiochemical Studies, The Fission Products,” Vol. 3 , C. I). Coryell and N. Sugarman, eds. Sational Nuclear Energy Series, Iliv. IV, 9, McGrawHill, New York, 1951.
LITERATURE CITED
(1) Ilzhelepov, B. S., Peker, L. K., “Decay Schemes of Radioactive Suclei,” pp. 360-4, Pergamon Press, SewYork, 1961.
RECEIVEDfor review May 12, 1964. Accepted June 5 , 1964.
Separation and Spectrophotometric Determination of Technetium in Fissium R. J. MEYER, R. D. OLDHAM, and R.
P.
LARSEN
Chemical Engineering Division, Argonne National laboratory, Argonne, 111.
b The process of distillation of technetium from sulfuric acid has been studied and successfully applied to the separation of technetium from uranium, ruthenium, und a number of other fission elements. Technetium is determined by measuring the absorbance of its toluene-3,4-dithiol complex a t 455 mp. The complex is formed in 9N sulfuric acid in the presence of bromine and extracted into isoamyl acetate. In the analysis of uraniumfission element alloys relative standard deviations of 0.67 and 2.070 were obtained a t the 0.030 and 0.0065% levels, respectively.
T
CORE of the Experimental Breeder Reactor-,II (EBR-11) will he made up of an alloy (fissium) containing 95% uranium, 2.5y0 molybdenam, Z.Oy0 ruthenium, and fractional percentages of rhodium, palladium, and zirconium. From time to time, the core of the reactor will be processed metallurgically to reestablish the fuel integrity and to remove certain undesirable fission products. 1:n the primary purification stel), melt refining, the fuel will be melted in a, zirconium oxlde crucible under an argon atmosphere and the Ilurified metal cast. The material remaining in the crucible after the ~ ~ o u r i noperation g (skull) will be further purified by a process known as the skull reclamation process. One of the stells of the latter process will consist of oxidation of the skull to facilitate its removal from the crucible. I!ecm~setechnetium-,99 ( 2 x lO5years) is a niajcr fission product, its behavior in both the melt refinin:; procrss and the HE
skull oxidation step had to be established. This was done using unirradiated fissium alloys to which technetium-99 had been added. The concentration range of interest was 0.005 to 0.2%. Several colorimetric methods would which have been reported (4,8-20) afford the necessary high sensitivity, but each of these methods was subject to interference problems from the other fissiuni constituents as well as the nitric acid used in the dissolution of the alloy. The distillation of technetium as the septoxide from sulfuric acid separates the technetium from interferences (6). Hydrobromic acid is added to the sample prior to the distillation to destroy nitrate and to prevent the volatilization of ruthenium as the tetroxide by keeping it reduced. Although technetium is also reduced by bromide in dilute sulfuric acid, it is reoxidized by sulfuric acid above 155” C. Quantitative distillation can he achieved even a t the tracer level with particular attention to cleanliness of the equipment and purity of the sweep gas. The high and variable sulfuric acid content of the distillate severely limited the choice of colorimetric methods available for the technetium determination. Thiourea (8) and thioglycolic acid (9) were investigated briefly but the color developments were prohibitively acid dependent. The thiocyanate method of Crouthamel ( 4 ) was coinpatible with the distillate and was particularly attractive hecauRe of its high sensitivity. However, the conditions which gave satisfactory color development with one batch of thiocyanate were completely unsatisfactory
for another batch. Two more recently published methods, one using 1,5diphenylcarbohydrazide (II) the other using p-thiocresol ( I ) , were not investigated. The detection method described herein basically that of Miller and Thomason (10) but with major modifications. The absorbance of the same yellow toluene3,4-dithiol complex of technetium is measured, but the conditions for obtaining it are quite different. The color can now be formed over a wide range of acidity and can be extracted into a variety of solvents. The application of the procedure reported here to the problem of determining the technetium-99 formed during irradiation of nuclear fuels is being pursued. The use of this method for the determination of burnup in the EBR-I1 as well as other reactors is being pursued. This will be reported in a subsequent publication. ~
EXPERIMENTAL
Apparatus. T h e distillation apparatus is shown in Figure 1. T h e heating mantle is a 100-ml. capacit’g, quartz - lined, aluminum - jacketed, Glas-col mantle designed to operat’e on 110 volts. The heating tape is 2 feet of 1;2-inch wide tape designed to operate on 110 volts and has a power rating of 96 watts. The distillation apparatus is cleaned initially by distilling approximately 5 ml. of perchloric acid through it. This is followed hy a thorough rinsing with distilled (not deionized) water. Thereafter, the apparatus, if in daily use? requires only a cleaning with hot sodium hypochlorite solution follo.rved by a thorough riming with distilled water. VOL. 3 6 , NO, 10, SEPTEMBER 1 9 6 4
1975
Figure 1 ,
Distillation apparatus
Soap, detergents, and deionized water are avoided because they introduce reductants into the distillation flask. Sulfuric acid rather than organic grease is used to lubricate the ground glass joints of the apparatus for the same reason. The life of the quartz-lined heating mantle can be prolonged by decreasing the applied voltage to the mantle toward the end of the sulfuric acid distillation. Reagents. T h e reagents required for the determination of technetium in fissium are listed below. h q u a regia mixture: 20 ml. of hydrochloric acid, 5 nil. of nit,ric acid, 0.5 ml. of hydrofluoric acid. Zinc-toluene-3,4-dithiol suspension: 12.5 mg. of "zinc dithiol" per ml. in 95y0 ethanol. The zinc dithiol, obtained from Fisher Scientific Co., w s finely ground under ethanol before dilut,ion to volume. Rroma.te solution A : 50 mg. of potassium bromate per ml. in water. Bromate solution B : 2.00 mg. of potassium bromate per ml. in water. Helium gas: Grade -4,obtained from C . S.13ureau of Mines. Sulfur dioxide gas : Commercial grade, obtained from the Matheson Co. Isoamyl acetate: 13. p. 137' to 142' C., obtained from Fisher Scientific Co., Eastnian Chemical Co., or Matheson Coleman & I3ell. *ill other chemicals are reagent grade. Standards. Ammonium pertechnet a t e solution wan obtained from Oak Ridge Sational Laboratory. St'andardiaation of this solution was accomplished b), 1)recipitating and weighing tetraphenylar,wnium pertechnetate according to the standard mcthod for rhenium ( 7 ) . Dissolution Prbcedure. Introduce approsimately 1 gram of fissium into an Erlcnnieyer f l a k and c o w r the ,;ample with al)prosiniatcly 5 nil. of 19 76
water. *Add 15 ml. of the aqua regia mixture as rapidly as the vigor of the reaction will permit. After hydrogen evolution ceases, heat for 10 minutes. Separate a n y residue (primarily ruthenium) by centrifugation, add 1 to 2 nil. of 6N sodium hydrouide, and reflux with 5 ml. of 5% sodium hypochlorite. Cool, acidify under reflux with concentrated hydrochloric acid, and add this solution to the aqua regia portion of the sample. Transfer to a 50-ml. volumetric flask and dilute to volume with water. Distillstion Procedure. T o the distillation flask add an aliquot of the dissolved fissiuni solution containing from 17 to 90 pg. of technetium, 10 ml. of concentrated hydrobromic acid, and 15 ml. of 1 8 N sulfuric acid. (More hydrobromic acid must be added if more than the prescribed amount of hy1)ochlorite is used in the fissium dissolution. As much as 20. ml. of hydrobromic acid can be %%rated.) Assemble the still as shown in Figure 1, and pass helium through it a t the rate of 1 to 3 bubbles a second. Set the heating tape Variac and the heating mantle Variac to give a distillation rate of 1 to 2 ml. per minute. (Settings of 90 and 110, respectively, will give this rate.) Discard the fraction boiling below 155' C. (The cut between the lonr and high boiling fractions can be made visually as well as by temperature because there is a definite increase in the viscosity of the condensate a t this point. In addition, the solution in the distillation flask begins t,o froth a t this point.) Turn off the heat'ing tape Variac. Catch the fraction boiling above 155" C. in 10 ml. of water contained in a 40-ml. graduated centrifuge tube immersed in an ire bath. (If smaller volumes of catch solution are used, technetium may be lost.) Continue the distillation until 0.5 to 1 ml. of liquid remains in the still. The temperature at this point will be approximat,ely 325" C. Lower the mantle and allow the apparatus to cool. While doing thia, be careful to readjust the helium flow so that the distillate is not forced up into the condenser. Wash the condenser with water until the volume reaches 25 ml. Complete the washings with approximately 10 ml. of 9N sulfuric acid. Transfer to a 50ml. volumetric flask and dilute to volume with 9.V sulfuric acid. Oxidation Procedure. Pipet an aliquot containing i to 35 p g . of technetium, from either the distillate or a standard solution, into a 50-ml. stoppered centrifuge tube. Dilute to approximately 20 ml., adding sufficient sulfuric acid to make the final concentration 9N. ;\dd approximately 5 ml. of bromate solution ;i and allow the solution t,o stand for 10 minutes. Cautiously add sulfur dioxide gas until the solution just turns colorless. Immediately add bromate solution 13 dropwise until the bromine color just persists. (Low results will be obtained if too much sulfur dioxide is added. This is indicated when more than 3 to 4 drops of bromate solution 13 are neceesary to restore the color.)
% ANALYTICAL CHEMISTRY
Color Development Procedure. Add 1.0 ml. of bromate qolution B, 4 ml. of 957, ethanol, and immediately thcreafter 1.0 ml. of zinc dithiol suspension. (The dithiol suspension should be shaken before it is used.) Shake ne11 and let stand for 1 hour. .Add 10.0 ml. of isoamyl acetate and shake for 1 minute. Centrifuge for 3 minutes to remove suspended water and solid particles from the organic phase. Transfer a portion of the organic phase to a spectrophotometer cell and read the absorbance a t 455 mp (technetium) and 680 mp (molybdenum, cf., Interferences) against a blank which has been carried through the oxidation and color development procedures. Calculate the amount of technetium using the following formula: Weight of Tc in mg.
=
and Afimare absorbance readings at 455 mp and 680 mp, respectively. The derivation of Equation 1 is presented in the Interference section. Preparation and Use of Tc95 Tracer. Technetium-95 (60 days), which had been codistilled with technetium-99 to ensure isotopic exchange was used in this work to investigate technetium losses during the dissolution of fissium metal, to aid in the establishment of conditions for quantitative distillation, and to investigate the distribution of technetium dithiol between the organic and aqueous phases after color development. The technetium-95 was prepared in the .irgonne National Laboratory cyclotron by deuteron bombardment of approximately 1 gram of molybdenum oxide. A bombardment carried out, for about 1000-pa. hours with deuterons of approximately 19.5 m.e.v. produced sufficient 're95 to last 3 to 4 months (0.1 e.). The irradiated molybdenum trioxide was dissolved in ammonium hydroxide and acidified with sulfuric acid. After t'he addition of Tc99 as a carrier, the Tcgj and Tcg9were distilled. The purity of the product was ascertained by gamma scintillation spectrometry. -4445
DISCUSSION A N D RESULTS
Volatility of Technetium. The literature concerning the volatility of technetium from hot nitric acid solutions is conflicting. Glendenin ( 6 ) was apparently able to evaporate nitric acid solutions of technetium to near dryness without loss of technetium. Embleton and Foreman (5) lost technetium under what were apparently the same experimental conditions. IZecause heat and nitric acid are necessary in the dissolution of fissium metal, the possibility of technetium losses by volatilization during this step was investigated. Technetium-95 tracer was added to several aqua regia di.swlut ions of fissinni nietal. IVhen the dissolutions were coml)lete! the solutions were diluted to volume and
aliquots were gamma counted. S o losses of technetium occurred. In contrast to the above observations, we have noted small (10%) losses of technetium during the aqua regia dissolution of nickel samples which contained known amounts of technetium. These dissolutions were much lengthier than the fissium dissolution, 3 hours us. 15 minutes. The fact that no technetium was lost j,n the dissolutions of fissium is appareni.ly attributable to two factors : the brevity of the dissolution and the presence of a strong reductant, uranium metall during most of the operation. Evaporation of the fissium solutions to dryness did result in technetium losses. This may be the result of higher temperatures after the sample goes to dryness. Distillation. The interference of nitrate and most of the fissium elements in the colorimetric niethods for technetium required t h a t a particular specific separation of technetium from the interferences b e made. I t appeared at, the outset t h a t the only fissium constituent which might not be separable by a distillation from concentrated acid \ u s ruthenium. Glendenin (6) had s,hown in his early work on technetium that trace amounts could be distilled qu.antitatively from sulfuric acid without volatilizing ruthenium if nitrate was first removed by treatment with hydrobromic acid. However, Anders ( 2 ) and Boyd, Larson, and N o t t a ( 3 ) were unable to achieve quantitative distillation consistently unless a strong oxidant such as cerium(1V) was present. Our initial work apparently substantiated the work of Boyd and of =\riders. Xnders attributed this phenomenon to reducing impurities in the sulfuric acid. In his review he suggested that, "Some effort should be made to find an oxidizing agent that is nonvolatile. stable in boiling sulfuric acid, strong enough to keep technetium in the +7 oxidation state, yet not so strong as to oxidize lower states of ruthenium to Ru04." Our efforts to find such an oxidant were unsuccessful. Vpon reinvestigation of the distillation from sulfuric acid in the absence of a strong oxidant, we found that the losses which we had e.ncountered in our initial exlieriments were the result of reaction of the vaporized technetium with impurities in t,he sweep gas and wit,h impurities on the walls of the distillation apparatus. We found that' quantitative distillations of even tracer amounts can be consistently obtained by being particularly attentive to the purity of the sweep gas and to the cleanliness of the distillation apparatus. The bromide which is added prior to the distillation to destroy nitrate also reduces pertechnetate. Hecause technetium ic readily distilled under these
rcducing conditions, the question arises: is a reduced species of technetium also volatile or is the technetium reoxidized to pertechnetate by sulfuric acid in the course of the distillation? T o resolve this uncertainty, the distillation behavior of pertechnetate and reduced technetium was studied. K h e n pertechnetate .is not reduced 1)rior to distillation, the technetium begins to distill a t approximately 110" C. and distills slowly over a large temperature range. Complete distillation is not achieved until 0.5 t o 1 ml. of sulfuric acid remains in the still and the temperature reaches approximately 325" C. This behavior is shown graphically by Figure 2. Increasing the amount of sulfuric acid initially present in the still does not alleviate the need to distill to the small final volume. When pertechnetate is reduced prior to the distillation with bromide, it does not begin to distill until 155' C. Above this temperature, 80 to 90y0 of the technetium distills rapidly, but once again, complete distillation is achieved only by distilling to a small volume of sulfuric acid. This result is also shown in Figure 2 . The coincidence of the curves above 155" C. indicates that the reduced technetium is reoxidized. That hot concentrated sulfuric acid rather than residual bromine is the effective oxidant for technetium is demonstrated by the fact that technetium which has been reduced by sulfur dioxide can subsequently be quantitatively distilled from sulfuric acid even under an inert atmosphere of helium. Although traces of fissium components are found in the dktillate, this appears to be the result of entrainment rather than codistillation. The amounts of fissium components in the distillate are small and are in the same proportions as those found in fissium. The degree of entrainment was checked by uranium, molybdenum, and ruthenium analysea of the distillates. The analyses showed that about 0.05yo of these fissium constituents were entrained. Oxidation State Adjustment. When the color development was carried out directly on the technetium fractions from fissiuni distillations, the results as compared with direct standards were invariahly low and e rra t i Tracer studies sh o wed t h a t a portion of the technetium did not extract into the isoamyl acetate and t h a t the fraction of tracer t h a t ' did extract was always equal to the fraction of the color t h a t developed. Since technetium(1V) does not react with dithiol to form a complex which is extractable into isoamyl acetate, it was concluded that some reduction of the terhnetium occurred in the catch solution. Technet iuni (VI I ) was probably reduced by the traces of bromide (8.
p 40 30
I
IlOOC 5
IO
15
I
155-C
20
25
30
ml DISTILLED
Figure 2. Effect of bromide on distillation of technetium from sulfuric acid X = Without bromide 0 = With bromide
known t o be present in the distillate. Localized heating which occurred when the sulfuric acid distillate hydrolyzed vias Irobahly a contributing factor in this reduction. T o obtain a solution in which all of the technetium was fully oxidized and yet one which was free of oxidants that would attack the dithiol during the color development, the 1)rocedure of oxidation with bromate, destruction of excess bromate with sulfur dioxide, and finally destruction of excess sulfur dioxide with dilute bromate soliiticn was devised. I3romate was chosen as the oxidant for two reasons: it and its reduction product bromine are easily destroyed, and their removal is easily followed by the disa1q)earance of the bromine color. Considerable care must be exercised when sulfur dioxide gas is being added to destroy the bromate and bromine because too much sulfur dioxide will again reduce the technetium and \)revent full color develo1)ment. The elimination of the last traces of bromine must be done slowly, a bubble a t a time, in much the same way that one apl)roaches the end ]mint in a titration. The gas addition must be discontinued immediately after the bromine color disalqiears from solution and any slight excess of sulfur dioxide must be destroyed immediately by adding dilute bromate solution until a very small excess of bromine is present. Color Development. Miller and Thomason (10) reliorted that ~ i e r technetate and toluene-3,?-dithiol, "dithiol," react to form two complexes, one y ~ l l o w (455 mpi). the othcr rose (540 mp). They formed these complexes by VOL.
36, NO. 10, SEPTEMBER 1964
1977
0 300
V W
2 a
s:
z
r
,0,150
0.100
I
5.0
Figure 4.
I
I
reacting pertechnetate with dithiol in an acid bolution and extracting the complexes as they formed into an organic solvent. To obtain complete color development the phases vere equilibrated intermittently for 1 hour or continuously for 15 minutes. They were able to obtain the yellow complex exclusively if they used 2N hydrochloric acid as the aqueous medium and carbon tetrachloride as the extractant. ;\t other acidities and with other solvents they obtained a mixture of the complexes. Our attempts to apply this method to pertechnetate solutions which were 9N in sulfuric acid resulted in a mixture of the complexes regardless of the extractant used. Our method evolved from a series of more or less empirical adjustments in Miller and Thomason’s procedure. Dithiol was replaced by the more stable reagent, zinc dithiol; the color was allowed to develop completely in the aqueous phase; and bromine was added during color development. The use of bromine is probably the most significant factor in the exclusive formation of the yellow complex. Control of the bromine concentration during color development is very impcrtant. -4 mixture of complexes is formed if tao little bromine is present; the dithiol is destroyed if too much bromine is present. Control of the bromine concentration is achieved by reacting a measured amount of bromate
t
I
I
10.0
I5 0
ZINC DITHIOL ADDED
Effect of dithiol
$
0.20ot
3a
0,100
I 20 0
25 0
1
on technetium-dithiol
color
When stored in the dark, the complex appeared to be stable for several days. The effect of sulfuric acid concentration on the formation of the yellow complex is illustrated in Figure 6. Sulfuric acid concentrations higher than 13,V were tried but the dithiol decomposed giving a cloudy organic phase. No readings were taken on these solutions. Figure 7 shows the effect of ethanol on the formation of the yellow complex. The amount of ethanol shown is the total added, both a5 pure ethanol and as ethanol in the zinc dithiol suspension. Some ethanol must be added to the technetium solution before the dithiol suspension is added. The reason for this is not known, but when simultaneous addition of the ethanol and dithiol was attempted, low results were obtained, With our revised procedure for obtaining the yellow technetiuni4ithiol complex, carbon tetrachloride, isoamyl acetate, and cyclohexane are all qatisfactory extractants. We use isoamyl acetate rather than carbon tetrachloride because with the lighter solvent the technetium is in the upper phase after extraction. This simplifies the transfer from the extraction vessel to the spectrophotometer cell. Interferences. Because the eypected concentrations of technetium in fissium were relatively low, 0.005 to O.27,, and because the character of the distillation was such t h a t entrainment wa3 bound to occur, the effect of each of the fissium com-
with the excess bromide already present as the result of steps in oxidation state adjustment part of the procedure. Control of the bromine concentration by bromate addition is far superior to the control provided by adding a measured amount of saturated bromine water solution. The effect of bromate on the formation of the yellow complex is shown in Figure 3. The effect of dithiol concentration on the formation of the yellow complex is shown in Figure 4. When 12 to 16 mg. are used, the intensity of the developed color is constant. The decrease in color when more than 16 mg. are added is due to the partial formation of the red technet,ium-dithiol complex. The effect of time on the development of the yellow complex is shown in Figure 5 . The times given in Figure 5 are those which elapsed between the addition of the dithiol reagent and the ext,raction of the complex into isoamyl acetate. Color development is complete in 45 minutes and there is no loss of color for a t least 3 hours. .\ mixture of the red and yellow complexes is obtained if the solutions are allowed to stand overnight prior to the extraction step. The yellow complex is more stable with respect to time once it is extracted and separated from the aqueous phase. Isoamyl acetate solutions of the yellow complex, stored in the light, showed no change in absorbance over a period of 24 hours.
0.2oot/
(mgs
/
W V
0.150
0
g a
0.100
0.0501
0.0501 0
Figure
1978
I
0.5
I 1.0
I
1.5
5. Effect of time
I
2.0 TIME, hrs
I
2.5
I
3.0
on technetium-dithiol
ANALYTICAL CHEMISTRY
I 3.5
5.0
I
7.0
I 8.0
I 90
I 10.0
I 11.0
I 12.0
I
13.0
L 14.0
NORMALITY OF SULFURIC ACID
4.0
color
I
60
Figure 6. color
Effect on sulfuric acid
on technetium-dithiol
0
2
0.100
a
1
I 2.0
Figure 7.
I
Effect of ethanol on technetium-dithiol color
ponents on t h e technetium determination was investigated. These effects were determined by carrying out a distillation in the presence of each of the ot,her components and then performing a color development. Absorbance measurements were made a t 455 mp. The results of these tests are given in Table I. That molybdenum is indeed an interference is furt’her demonstrated by the spectra shown in Figure 8 : .4 is the spectrum of the yellow technetium-dithiol complex, B is the spectrum of the molybdenumdithiol complex, and ‘Cis the spectrum obtained when a color development was carried out on a blank. fissium distillate. This interference from molybdenum does not become significant until the concentration of technetium in fisium drops below 0.17,. Figure 8 shows that’ the molybdenum complex absorbs most strongly at’ 680
Table I.
Amt. present In distillaticln, mg. 15 1
Ru Rh Pd Ce
1
3 2
Zr
5 400
I;
15
hf 0
Absorhancea at 465 mp 0 0 0 0 0 0 0
000 000 000 000 000 000 042
KOT c present
Table 11.
Results of Determination of Technetium in Fissium s o . of
Technetium deterAdded, yc Found, av. yc minations 0 0 0 0 0
WAVELENGTH ( m p l
Absorption spectra of dithiol complexes
Figure 8. A. E. C.
mp while the technetium complex absorbs most strongly a t 455 mp. This difference in absorption makes it possible to correct for the molybdenum interference. The total absorbance a t 455 mp and at 680 mp can he expressed as follows:
+ K2CI
(2)
A680 = K ~ C T ~KeCr
(3)
’‘1165
= KlCTa
+
where ; 1 4 5 s and are the absorbances a t those wave lengths. CTc represents the milligrams of technetium in 10 ml. and C, represents the milligrams of interfering ion. K,, KP, K 3 , and K4 are constants. Solving Equations 2 and 3 si.multaneously gives
Effect of Fissium Components on Analysis
Element
a
I 8.0
4.0 6.0 ETHANOL ADDED (rnls.)
0299 0199 0133 0100 0066
0 0060 0 0033
0 0:102
n 0 0 0 0 0
019s
0135 01 0 2 O(l6.i MI61
O(l36
10 3
4 4
8 1 2
With - 1 6 pg. of technetium With -6 p g . of molybdenum Distillate from - 4 0 0 mg. of firsium
The method was tested by analyzing fissium solutions containing various concentrations of technetium. The results of this testing are given in Table 11. The results a t the O.O030j, level begin to show a high bias. This bias is caused by the large molybdenum correction, 307,, a t this level. The precision of the method was tested a t the 0.030% and a t the 0.006570 levels. Relat’ive standard deviations of 0.67 and 2.OyG, respectively, were obtained with no apparent bias. LITERATURE CITED
(1) AI-Kayssi, M., hfagee, R. J., Talanta 10, 1047 (1963). ( 2 ) Anders, E., “The Radiochemistry of Technetium,” Sational Academy of
Sriences. Nuclear Science Series NASNS-3021, p. 13, USAEC (1960). (3) Bnyd, G . E., Larson, Q. V., Motta, E. E., J . Am. Cherri. Sor. 82, 809 (1960).
The ratio Kzi’K4was evaluated from a series of molybdate solutions which !?-ere put through the color development procedure and read at 680 mp and 455 nip. 13y substituting these values into Equations 2 and 3 and solving for IC2 /K4, an average value of 0.640 was obtained. This value was verified by develoliing the dithiol color on a series of di+tillates from fissium which contained no technetium. The contants K1 and KI were evaluated a t 16.71 and 12.08 by developing the dithiol color on a $cries of standard technetium solutions. (The value of 16.71 for Kl gives a molar absorptivity of 10,iOO. 3Iiller and Thomason (10) reported a \ d u e of 15,000.j Substituting the values for thi. constants into Equation 4 $ one obtains the correction factor given in Equation 1.
(4) Crouthamel, C. E., ANAL.CHEM.29, 1 i 5 6 i1957). ( 5 ) Embleton, J. R., Foreman, J. K., I’. K. At. Energy Authority Production Group PG, R e p t . 93 ( W j (1960). ( 6 ) Glendenin, 1,. E., “Radiorhyiral Studies: The Fission Products, S a tional Yuclear Energy Series, Div. IV-9, Paper 259, C. 1). Coryell, N. Sugarman, eds., p. 1545, McGraw-Hill, S e w York, 1951. ( 7 ) Hillehrand, W.F., Lundell, G. E. F., Bright, €I. A , , Hoffman,,, J. I., “Applied Inorganic .4nalysis, 2nd ed. p. 321> Wiley, Yew York, 1953. (8) LIagee, It. J., Jasmin, F., Watson, C. I,., l ’ d ~ n t a2 , 93 (1959). ( 0 ) LIilIer~ F. J., Thomason, P. F., A N A L CHEM. . 32, 1429 (1960). (IO) / b i d . , 33, 404 (1961). i l l ) Lliller, F. J., Zittel, H. E., /bid., 35, 299 (1O6;3). RECEIVEDfor review April 9, 1064. Accepted June 16, 1964. Work performed under the auspices of the (.. H. A t o m i c Energy Commission under contracat So. ~~-:31-10g-rrig-~38. VOL. 36, NO. 10, SEPTEMBER 1 9 6 4
1979
