Table
Procedure Used
He Flow Rate, C.F.M.
1 1 1 1
0.008 0,008 0.008 0,008
Ill.
Data for Reproducibility of Sampling and Separation Procedures
He Purge Rate, C.F.M. 0.02 0.02 0.02
Sampling Time, Min. 45 45 20 45
Decay Sampling Time to Bed Xe-Kr Temoperature, Separation, F. Min. -112 30 -112 30 - 112 30 -112 30
R(Kr*sm), AtomlMin.
R(KrS7)! AtomlMin.
/x
lo-)
( X lo-*:
...
2 10
... ... ...
2.16 2.01 0.02 2.01 Av. 2.07 3Z 0.07 3 0,008 0.008 45 -75“ 30 1.5gb 3 0,008 0.008 45 -75“ 30 1.57 1 0,008 0.02 45 - 112 30 1.51 Av. 1.56 3Z 0.04 Separated on sampling bed and contained on chromatographic column at -112‘ F. The following experiments were performed after a change in fission gas source conditions
a
b
D(T)
=
the disintegration rate of the nuclide on the sampling bed, atom/minute
This correction factor was applied to correct the results of individual assays to a common basis-i.e., the number of atoms per minute arriving at the sampling trap. After the methods for identification and determination of the several nuclides were established, a series of experiments mas performed t o test the reproducibility of the gamma spectrometry techniques for each nuclide under identical sampling and separation conditions. Procedure 2 was used for the krypton samples, and Procedure 1, for xenon. Experimental data for K F m , Krs7, Xe133,Xe136, and Xe138are shown in Table 11. The precision of the assays was about 7% for K r 8 5 m and K r S 7 and somewhat better than iyofor the xenon isotopes. The reproducibility of the sampling and separation procedures was demonstrated in additional analyses for krypton by varying the flow rates of the transport gas or the sweep gas, the sampling time, or the specific separa-
tion procedure. The additional data are summarized in Table 111. The first group of data were obtained under the same experimental conditions as the krypton data in Table I1 and are in good agreement The latter group mere obtained under somewhat different fission gas source conditions. The standard deviations obtained in these tests are less than those in Table I1 Therefore, the deviations may be attributed primarily to the spectrometry techniques. I n summary, a rapid method has been developed for sampling, separation, and gamma spectrometry assay of five niediuni and short lived fission gas nuclides, as n ell as a semiquantitative method for 3-minute KrS9. Specific procedures. rvhich yield data nith a precision better than 7’%> have been demonstrated for the analysis of these six nuclides in a helium stream having moderate velocity and ambient temperature. I
ACKNOWLEDGMENT
The authors thank R. H. Marsh for his assistance in portions of thii pro-
1.25* 1.12 1 2; 1 31 zk 0 07
gram and Paul Kruger for hi. helpful comments and suggestions. LITERATURE CITED
(1) Browning, W. E., Bolta, C C.. U. S. Atomic Energy Comm. Rept. ORNL-
2116 119571. %
,
( 2 ) Browning, W. E., ad am^, R. E., Ackley, R . D , Ibid, ORNL-CF-59-6-
47 (1959). (3) Friedlander, G., Kennedy, J. W., “Introduction to Radiochemistry,” Wiley, New York, 1940. (4)Glueckauf, E., Atomic Energy Research Establ. 1Gt. Brit.) CR-2415 (1957); CR-2434‘(1958) ’ (5) Grandy, G. L., NSEC, unpublished data, 1957. (6) Grandy, G. L., Koch, R C., Rev. Sci. Instr. 31, 786 (1960). (7) Koch, R. C., Grandy, G. L., Sucleonics 18, No. 7,76 (1960). (8) Koch, R. C., Grandy, G. L., U. S. A4tomicEnergy Comm. Rept. NSEC-7 (1957). (9) Ibid., NSEC-12 (1958).
RECEIVED for review June 6, 1960. Accepted September 19, 1960. Work sponsored by U. S. Atomic Energy Commission under contract No. AT(30-1)1940 with the Babcock and Wilcox Co. These data are published by permission of both organizations.
Spectrophotometric Determination of Niobium and Molybdenum with 8-QuinoIinoI in Uranium-Base Alloys KENJI MOTOJIMA and HlROSHl HASHlTANl Division o f Chemistry, Japan Atomic Energy Research Institute, Ibaraki-ken, Japan
b A rapid and accurate spectrophotometric method for the determination of microgram quantities of niobium with 8-quinolinol can b e utilized for the analysis of uranium-niobium alloys containing 5% or less of niobium. The determination of niobium i s based on the extraction of its quinolinate with chloroform and spec48
ANALYTICAL CHEMISTRY
trophotometric measurement of the extract, Extraction of uranium is prevented by use of fluoride ion as a masking agent. This method can also b e used in the analysis of niobiummolybdenum-uranium ternary alloys containing up to 5% of additives; both niobium and molybdenum are determined readily.
T
HE preparation of many kinds of niobium-uranium alloys containing up to 1% niobium by the Metallurgy Research Group of the Japan Atomic Energy Research Institute necessitated a rapid and accurate analytical method for the determination of niobium. The conventional gravimetric methods (6-8, 11) for niobium tend to
be tedious, time-consuming, and of uncertain accuracy, especially when the niobium content is low. Banks et al. (1) and Susano, Menis, and Talbott (12) discussed a differential spectrophotometric method using hydrogen peroxide in concentrated sulfuric acid. However, these gravimetric and spectrophotometric methods cannot be used for the determination of a small amount of niobium in uranium. Kassner and coworkers (4) proposed a spectrophotometric measurement of a chloroform solution of niobium quinolinate, which had been extracted from an ammoniacal citrate solution. A1though this method has high sensitivity, it seemed to the present authors that the optimum p H for niobium was not utilized. I n this investigation, fundamental studies for the extraction of niobium quinolinate were made and a suitable condition for niobium was found. The established method was then applied to the separation and determination of niobium in uranium. Further experiments were made for determining both niobium and molybdenum in uranium. EQUIPMENT
A Shimadzu, QR-50 spectrophotometer nith 1-em. glass cell was used for all absorbance measurements. A glass electrode pH meter (Horiba, illode1 11-3) was used for pH measurements. An Iwaki Model KRI shaker, Squibbtype, 200-ml. separatory funnels which are graduated a t 10, 50, and 100 ml., a special pipet for taking a definite volume of chloroform, and 30-mi. glass-stoppered Erlenmeyer flasks n-ere used for the extraction. REAGENTS STAND.4RD
NIOBIUM
SOLUTION.
A
standard niobium solution m-as prepared by dissolving 0.200 gram of niobium metal in sufficient hot nitric and hydrofluoric acids. The solution was evaporated to fumes with 5 ml. of sulfuric acid to remove most of the nitric and hydrofluoric acids, and then diluted to 1 liter. The solution contains 0.200 mg. of niobium per ml. Working solutions, prepared by diluting this solution with mater, contained a negligible amount of fluoride ion. STANDARD TANTA4LUV SOLUTIOK. A
standard tantalum solution was prepared by dissolving pure metal by the above method. OTHERSTAPI’DARD SOLUTIONS. Standard solutions of vanadium(V), iron(III), copper, molybdenum(VI), titanium(1V) , aluminum, chromium(III), manganese (11), and tungsten(VI) were prepared from either pure metals or pure salts. ~-QUINOLINOL SOLUTION (1%). I n 5 ml. of glacial acetic acid 2 grams of pure 8-quinolinol was dissolved by warming and diluted to 200 ml. with water. PURIFIED CHLOROFORM was used.
CARBONATE-CYANIDE WASHIKG SOLU-
niobium and mol! bdenum are detcrmined by one of the procedures nienAbout 100 ml. of 2M ammonium tioned below, depeiidiiig on the conipocicarbonate solution and about 20 ml. of 1 M potassium cyanide solution were tion of the sample. mixed, and the volume was brought to Determination of Niobium in Nio1 liter. The resulting solution was bium-Uranium Alloys. About 50 ml. shaken nith about 20 ml. of 2% .8of the dissolved sample solution conyuinolinol-chloroform solution and with taining 5 to 100 pg, of niobium is diluted about 20 ml. of chloroform to remove t o 50 to 70 ml., and treated nith 3 nil. of 8-quinolinol solution. Then the pH interfering metals present as impurities of the solution is adjusted to 5.1 0.2 in the reagents. Then, 10 ml. of 5% 8-quinolinol (acetic acid solution) was with ammonium acetate and ammonium hydroxide, and the solution is transadded to the solution. The solution ferred to a separatory funnel. After the was used after filtering through a wet volume is brought to 100 ml., extraction paper. is made nith exactly 10 ml. of chloroPOTASSIUM CHLORIDE-HYDROCHLORIC form. The extract is washed nith 50 ACID WASHINGSOLUTION. The pH of 0.1M potassium chloride solution ml. of the carbonate-cyanide washing (500 ml.) was adjusted to 1.9 to 2.5 solution. Potassium chloride-hydrowith 2 N hydrochloric acid. The soluchloric acid washing solution is more tion was diluted to 1 liter, and shaken useful when the niobium content is more mith chloroform. After wparation of than 1%. Niobium is determined by measuring the absorbance of the extract the chloroform, the aqueous solution was filtered through a wet paper. a t 385 mp. When the niobiuni content URANYL NITRATESOLCTION.A soluof the sample is less than 1%, microtion containing 0.01 gram of uranium gram quantities of iron. which is always per ml. was obtained by dissolving the present in uranium, interfere with the niobium determination. In this case, corresponding amount of reagent grade two absorbances of the extract are U02(Y03)z6Hz0 (Baker & ildamson) in water. measured a t 385 and 470 mp. The The other solutions were prepared absorbance a t 470 nip is based on the from reagent grade chemicals. All quinolinate of iron alone. Therefore, water used was purified, first by disniobium can be determined in the tillation and then by passage through a presence of a small amount of iron by deionizing column. using the following formula:
TION.
PROCEDURE
General Procedure and Preparation of Calibration Curve. About 50 ml. of slightly acid solution, containing from 5 to 100 pg. of niobium, is treated with 3 ml. of 1% 8-quinolinol solution, and the pH is adjusted to 2.8 to 10.5. The solution is transferred to a separatory funnel and the volume is brought to 100 ml. Extraction is made nith exactly 10 ml. of chloroform by vigorous shaking for 1 minute. The chloroform layer is drann off into an Erlenmeyer flask containing 1 gram of anhydrous sodium sulfate, and is shaken to remove droplets of water. Then its absorbance is measured using a blank as reference. Niobium is determined by use of a calibration curve prepared by similarly treating a series of known amounts of niobium. The calibration curye ia prepared by taking 5 to 120 pg. of niobium. A linear relationship betn een niobium concentration and the absorbance is obtained up to 100 pg. When the extraction is made with 20 ml. of chloroform, this relationship holds to 200 pg. Preparation of Sample Solution. An alloy sample containing not more than 5% of niobium or niobium and molybdenum is neighed into a platinum dish and dissolved in a mixture of nitric and hydrofluoric acids. When dissolution is complete, the solution is treated with 5 ml. of sulfuric acid and evaporated to strong fumes. The solution is cooled and a definite amount of sodium fluoride solution, corresponding to 250 mg. of fluoride ion for each 1 gram of sample, is added. After diluting, a proper aliquot is taken into a polyethylene beaker. Then
where C N b = micrograms of niobium present, A = absorbance measured, and a = absorbance per microgram of niobium or iron. The values of a?:&, and a:;,, are found from the calibration curves for niobium and iron a t 385 and 470 mp, respectively. In this exlicriment, the values n-ere: a:&
=
0.0088
a z o = 0.0110 =
0.0110
Determination of Niobium and Molybdenum in Niobium-MolybBACKdenum-Uranium Alloys. EXTRACTION DIFFEREKTIAL NETHOD. About 50 ml. of the sample solution, containing not more than 200 p g . each of niobium and molybdenum, is treated n.ith 8-quinolinol. After the pH of the solution is adjusted to 5.1 =t 0.2, and the volume is brought to 100 ml., the extraction is made with exactly 20 ml. of chloroform. The washing is done as described above. Then the chloroform solution is divided into two fractions. One fraction is shaken with about 50 ml. of 0.05M oxalic acid solution which is saturated with chloroform, to remove niobium. By this treatment, microgram quantities of iron present in the sample as an impurity are also removed. The absorbance of the other fraction is measured a t 385 and 470 mp using this backextracted solution as reference. Niobium is determined by the use of the previously described formula. I n this VOL. 33, NO. 1, JANUARY 1961
49
0.6 r
4
6
8
1
0
PH Figure 1 . Effect of pH on extractability of niobium quinolinate Each contains 50 pg. of niobium
experiment, the values of the absorbance per microgram of niobium and iron were: a::, = 0.00420
a:;, = 0.00525 a::,
=
0.00525
On the other hand, molybdenum is determined from the absorbance of the washed extract a t 380 mp by using a blank as reference. I n this experiment, the absorbance per microgram of molybdenum was 0.00415. EXTRACTION
OF
NIOBIUM
QUINOLINATE
Wave Length. The maximum absorption of the niobium quinolinate extracted with chloroform at 385 mp (4) has been confirmed, and this wave length has been adopted in the present investigation. Effect of Variables. pH. A series of several solutions each containing 50 pg. of niobium was treated with 3 ml. of 8-quinolinol solution and enough acid or base to fall within a p H range from 1 to 12. Then extractions were made and the absorbance of the extracts was measured, by the procedure mentioned above. pH measurements
' 3
3
5
6
PH
131
Figure 2. EfFect of pH on extractability of niobium quinolinate in presence of fluoride Each contains 50 pg. of niobium 1. 1 0 m g . F 2. 5 0 m g . F -
3.
50
100 mg. F-
ANALYTICAL CHEMISTRY
were made on the aqueous layers after extraction. The results obtained are shown in Figure 1. Extraction is almost complete over a pH range from 2.8 to 10.5. ANOWKTO F REAGENT. When more than 2.0 ml. of reagent solution was used, the absorbances were reasonably constant. Therefore, 3 ml. of 8-quinolinol solution was sufficient. DIGESTION.The results of several experiments showed that no digestion is necessary. SHAKINGPERIOD.The quantitative extraction of niobium quinolinate with chloroform seems to be attained by vigorous shaking for 30 seconds. OTHER SUBSTANCES.The effects of fluoride, tartrate, citrate, oxalate, and disodium hydrogen (ethylenedinitril0)tetraacetate (EDTA) on the relationship between pH and extractability of niobium quinolinate were examined (Figures 2, 3, and 4). As the amounts of the reagents are increased, the pH range for the quantitative extraction of niobium quinolinate becomes more limited and extraction is incomplete. The effect of carbonate is not negligible, as shown in Table I. Table 1. Effect of Extractability of 4.44 Carbonate So1n.b Added, M1. 0 1
Carbonate on Niobium" Absorbance at 385 M p 0.540
0.495 0.420 5 0.385 7 0.272 10 0.205 50 p g . of niobium present in each case. Ammonium carbonate used. 3
*
Acetic acid does not interfere with niobium extraction. However, in this case, the extract must be washed with ammoniacal solution to remove acetic acid which contributes to the absorption of 8-quinolinol a t 385 mp. When hydrogen perioxide is present, a film tends to form inside the separatory funnel during extraction, and this causes low recoveries of niobium. Sodium sulfite in acid medium completely prevents the extraction of niobium. I n this case, if the aqueous layer is treated with hydrogen peroxide followed by the removal of excess hydrogen peroxide by boiling, niobium is quantitatively extracted and recovered. These properties may be of value for the separation of this element from others. APPLICATION TO URANIUM ALLOYS
Masking Agents. Because uranium quinolinate is readily extracted with chloroform as well as niobium, a suitable masking agent and accurate
.
_ - ~ 6
4
IC
8
?t-
Figure 3. Effect of pH on extractability of niobium quinolinate in presence of tartrate or citrate Each contains 50 g. of niobium 1 3 mi. of 1 O ~ L Ktartrate N ~ roln. 2. 10 ml. of 10 0 KNa tartrate s o h 3. 10 mi. of 5Jcitric acid soh.
p H adjustment are essential to the separation of niobium from uranium. Acetic acid, which has been widely used as a masking agent for uranium (3), proved unsuitable for separating niobium from uranium, because when more than a certain amount of uranium is present the extraction of niobium quinolinate becomes incomplete, as shown in Figure 5. The reason for this is not clear. Although fluoride affects the extraction of niobium, as shown in Figure 2, the suitable pH range for the quantitative extraction of niobium, when considerable uranium is present, shifts to the acid side, because the fluoride is consumed by the uranium to form a soluble complex. When the amount of fluoride ion is fixed a t 50 mg., the p H range for the quantitative extraction of niobium is changed with the amount of uranium, as shown in Figure 6. Therefore, niobium can be separated from uranium by adding a definite amount of fluoride and selecting a suitable extracting p H which is varied according to the amount of uranium; however, this
0 22 m
:
02
c 1
, 8
6
8
10
PY
Figure 4. Effect of pH on extractability of niobium in presence of oxalate or EDTA 1. 2.
Each contains 50 pg. of niobium. 10 mI. of 5% ammonium oxalate soh. 3 ml. of 5 % EDTA soh.
0--0--0--0--3
Table
II.
Uranium Taken, Mg.
Determination in Uranium”
\J
of Niobium /
u..
Niobium, p g . Added Foundb
0
i
*\
I
,
I
4
a
6 Uranium present, rng. 2
200 300
Figure 5. Effect of uranium on determination of niobium
’
1
2
- ~-
400
__
n’
3
_ _ L _ -
35
5C
10
100
method is tedious. On the other hand, if the ratio of fluoride ion to uranium is defined, a suitable extracting p H range can be chosen-for example, when 250 mg. of uranium is treated with 50 mg. of fluoride ion, this p H range is 4.9 to 5.3. By use of these properties, 5 to 100 pg. of niobium in not more than 300 mg. of uranium can be successfully extracted. However, under these conditions a small amount of uranium is extracted and must be removed before niobium determination. Washing with ammonium carbonate solution effectively removes uranium from the extract. Some niobium is eliminated by this washing, but this can be prevented by the preliminary addition of 8-quinolinol to the washing solution. The data obtained by using the proposed procedure are shown in Table 11. Uranium can also be removed with a potassium chloridehydrochloric acid washing solution. Effect of Foreign Metals. The behavior of many foreign metals was studied under t h e same conditions as for the separation of niobium from uranium. These considerations may
0 4 -
10.3
49.8
25 50
Acetic acid used as masking agent Glacial acetic acid 5 ml., p H 5 to 5.5
2
10
50
EO
PH Figure 6. Effect of p H on extraction of niobium in presence of uranium and fluoride Each contains 50 mg. of Auoride and 50 pg. of niobium 1. 200 mg. uranium present 2. 100 mg. uranium present 3. Nouranium
10
25 50 100
9.7 24.8 49.9 9.5 23.9 47.6 96.0
Average of two determinations.
be necessary in the analysis of uranium alloys containing relatively large amounts of impurities. In this experiment, 50 to 200 pg. of each metal was extracted from solutions containing 250 mg. of uranium and 50 mg. of fluoride ion, by a procedure similar to the one finally adopted. Cranium in the extract was removed by washing with either 50 ml. of a potassium chloride-hydrochloric acid washing solution or an ammonium carbonate solution containing 1 ml. of 3y0 8-quinolinol solution. The relationship between extractability of these metals and pH is shown in Figure 7 . Vanadium, ferric iron, copper, molybdenum, and some titanium and nickel are extracted as well as niobium a t p H 4.9 to 5.3. About 50 pg. of aluminum, chromium, and manganese, and 200 pg. of tantalum, tungsten, and zirconium are not extracted a t all. The extractedvanadium, nickel, and copper can readily be removed from the organic layer by washing with a carbonate-cyanide solution. The methods for eliminating molybdenum and iron interferences are described below. When niobium content is moderately high and other interfering metals are negligible, washing with a potassium chloride-hydrochloric acid solution to eliminate uranium may be preferable to washing with a carbonate solution, because this washing solution is easily prepared and is stable. The relationship between the extent of stripping of these metals and the p H of the washing solution is shown in Figure 8. I n these experiments, ClarkLubs buffer solutions were used. By washing for 1 minute, about 1 mg. of uranium in chloroform is readily removed a t p H 2.7, while niobium remains quantitatively even a t pH 1.9.
i 2’
4
45
1
50
PH
100
* Fluoride ion used as masking agent. 6
__L-
Figure 7. Extraction behavior of metals in presence of uranium and fluoride Each contains 200 mg. of uranium and 50 mg. of fluoride ion Amounts of metals tested (pg.), 50 Cu, 50 Fe, 50 Mo, 5 0 Nb, 40 Ti, 100 V
Consequently, the pH of the washing solution should be adjusted to 1.9 to 2.5. Determination of Niobium and Molybdenum in Their Uranium Alloys. Molybdenum quinolinate can
be quantitatively extracted with chloroform, and the extract has a n absorption maximum a t 373 mp (9). By measuring the absorbance of the extract a t 380 mp, microgram quantities of molybdenum can be determined ( 2 , 9 ) ,and this method has been applied to the determination of this metal in uranium (IO). As described above, molybdenum is also quantitatively extracted with niobium, and the extract is so stable that it is not changed by washing with acid solutions such as 0.1M hydrochloric acid or 0.05M oxalic acid. Therefore, the determination of niobium is seriously affected by molybdenum. On the other
Figure 8. Stripping of metal quinolinate with various buffer solutions Voi. of chloroform soh., 10 ml. Vol. of buffer soh., 50 ml. Approximate amounts of metals tested (pg.), 25 AI, 50 Cu, 50 Fe, 50 Mo,5 5 Nb,
45 TI, 1000 U, 50 V VOL 33, NO. 1, JANUARY 1961
51
Table 111.
sample No.
Metal Taken, Grams Uranium Niobium 4,3398 5.7073 5.9342
1 9
3
Recovery of Niobium from Synthetic Mixtures
0.0763 0.1022 0,2018
Aliquot of S o h . Used for Detn. 10/20,000 10/40,000 5/50,000 10/50,000 15/50,000
20/50,000
25/50,000 a
06
Niobium Content, 70 Calcd.a Found 1.73 1.76 3.32 3.32 3.32 3.32 3.32
1.76, 1.73 1.78, 1.78 3.34, 3.33 3.35, 3.34 3.35, 3.34 3.28, 3.28 3 23, 3 23
Theoretical amount of niobium. E
4
o
PH
hand, extracted niobium can readily be stripped off with the oxalic acid solution, the pH of which is below 2.4. The relationship between the pH of the washing solution and the extent of stripping of niobium, molybdenum, and some of other metals is shown in Figure 9. Making use of these results, it is possible to determine both niobium and molybdenum which have been extracted with chloroform as quinolinate. The determination method for niobium may conreniently be called a back-extraction differential method. The details are described in the proposed procedure. Results. The results obtained from the analysis of three synthetic samples of niobium-uranium alloys and simulated sample solutions of niobium, molybdenum, and uranium are shown in Table I11 and IV. The validity of the method n as proved by
Table IV.
Determination of Niobium and Molybdenum in Uranium“
Taken, pg. Xiobiurn Molybdenum 10
10 10 25 25 25
50 50
60
inn
-__
100 100 200 200 200 a
b
52
these data. The proposed method was applied t o the determination of niobium or molybdenum in a number of experimental niobium-uranium alloys and molybdenum-uranium alloys nominally containing 0.05 to 1% of these metals. The results indicate that the method provides reasonably reproducible figures and is very reliable. This method cannot be extended to the analysis of alloys containing more than 5% of niobium or molybdenum, because the control of the relation between amount of fluoride added and extracting pH becomes difficult. When a low content of niobium is treated. common impurities in uranium such as aluminum, iron, and nickel do not interfere with the determination of niobium. The differential method is recommended for determining niobium in the presence of molybdenum. By using this method, both niobium and
25
100
200 25 100 200 25 100 200 26 100 200 25 100 200
AS$jb
0.050 0.052 0.044 0.134 0.135 0.130 0.256 0.255 0.251 0 514 0.509 0.496 1.065
0,992 0 892
A 3*oc
0.103 0.418 0.839 0.101 0.409 0.809 0.105 0.419 0.819 0 104 0.420
0.816 0.106 0.420 0.838
Found, pg. Niobium Molybdenum 9.5 9.9 8.4 25.5 25.9 24.8
48.8 48.5 47.8 97 8 96.9 94.7 203 189 170
Each contains 200 mg. of uranium. Absorbance a t 385 mp of first extract against back-extracted solution. Absorbance a t 380 mp of back-extracted chloroform solution against blank.
0
ANALYTICAL
CHEMISTRY
24.8 101 152 24.4 99.1 196 25.2 101 197 26 1
ioi
~
197 25.6 101
202
Figure 9. Stripping of metal quinolinate with oxalic acid at various pH values Vol. of chloroform soh., 10 ml. Vol. of oxalate soh., 5 0 ml. Approximate amounts of metals tested (pg.), 5 0 Cu, 50 Fe, 75 Mo, 5 0 Nb, 50 Ti, 40 V
molybdenum are simultaneously determined, but in the presence of ten times as much molybdenum as niobium the method is not recommended for the determination of niobium. LITERATURE CITED
(1) Banks, C. V., Burke, K. E., O’Laughlin, J. W.,Thompson, J. A., ANAL.
CHEM.29,995 (1957).
( 2 ) Gentry, G. H. R., Sherrington, L. G., Analyst 75, 17 (1950). (3) Hollingshead, R. G. W., “Oxine and Its Derivatives,” Vol. 11, p. 436,
Butterworths, London, 1954. (4)Kassner, J. L., Garcia-Porrata, Asdruhal, Grove, E. L., ANAL.CHEM.27, 492 (1955). (5) Kriege, 0. H.?. “Gravimetric Determination of hiobium in UraniumNiobium Alloys,” U. S. At. Energy Comm. Rept. LA-2049 (1956). (6) Milner, G. W. C., At. Energy Research Estab. (G. Brit.), “Analysis of Uranium-Niobium Alloys,” AERE-C/R-852 (1952). (7) Pvlilner, G. W. C., Barnett, G. A., Smales, A. A., Analyst 80, 380 (1955). (8) Milner, G. W. C., Wood, A. J., At. Energy Research Estab. (G. Brit.), “Analysis of Uranium-Tantalum and Uranium-Niobium Alloys,” AEREC/R-895 (1952). (9) Motojima, K., Hashitani, H., B u m e k i Kagaku 9, 151 (1960). (10) Motojima, K., Izawa, K., Japan At. Energy Research Institute, unpublished work. (11) Rodden, C. J., “Analytical Chemistry of the Manhattan Project,” McGraw-Hill, New York, 1950. (12) Susano, C. D., Menis, O., Talbott, C. K., ANAL.CHEW28, 1072 (1956).
RECEIVED for review March 28,1960. Accepted August 15, 1960.
