V O L U M E 2 3 , N O . 1, J A N U A R Y 1 9 5 1 experiment varied more than those which would actually be encountered. Proper preservation must, however, be emphasized. RANGE O F VALUES
I n 12 normal women students, 21 to 24 years of age, all living in and receiving their meals a t the same dormitory, and having similar work, the average neutral 1;-ketosteroid excretion varied from 7.9 to 10.9 mg. per 24 hours. A normal 1-month-old male infant excreted 0.5 mg. per day; 5 other children, 4 to 11 years, all excreted less than 1.5 nig. per day. In a case of precocious puberty-a male child aged 8-the value was 6 1; in a 14-yearold male child, after pubprty, 5 1. Results in 33 male and 58 female patients above 16 years of age will be discussed elsewhere. Six normal males were included in this series of patients, and 5 of these excreted 11.5 t o 18.8 mg. of neutral IT-ketosteroids pc’r day For 4 normal women included among the female patients, the values were thp same as in the group of women students.
123 T a b l e XII.
Adjusted pH 1.0 3.0 Sample C B Ketosteroid value before adjurtinent of ~ l i , mg./liter 11.2 . 8 3 Value after adjustment of DH a n d standine. hours 5 min. 10.8 8 . 3 1 10.5 6 . 1 2 9 . 8 7.0 3 1 0 . 4 8.4 1 9.9 7.7 21 9.6 8.0
LITERATURE (1)
NO.
17-Ketosteroid Found Before After kaolin kaolin M g . an I liters
6.0 8 . 0 B C
10.0 C
7.9
9,6
10.3
7.9 8.0
10.2 9.8 9 . 8 11.6
7.2 7.7 7.0
10.0 1 0 . 2 10.5 10.6 9.7 10.1
7.8 1 0 . 8 1 0 . 1
crrm
Beher, W. T., and Gaehler, 0. H., Federation Proc., 8,
183
(1949).
(4)
Bitman, J., and Cohen, S. L., Ihid., 9, 152 (1950). Bradbury, J. T., Brown, E. S.,and Brown, W. E., Proc. SOC. Ezptl. Bid. hfed.,71, 228 (1949). Buehler, H. J., Katsman, P. A , , and Doisy, E. .A,, Federation
(5)
Engstrom, W. W.,and >lason, H. L., Eiidocririology,
(2) (3)
Proc., 9, 157 (1950).
‘Table XI. Recovery of Urinar) h-eutral 17-Ketosteroicib a f t e r Kaolin T r e a t m e n t of Pooled Male Urines Sample
S t a b i l i t y of Urinary 17-Ketosteroids at Various pH Values
33, 229
(1943).
Gallagher, T. I?., Peterson, D. H., Dorfman, R. I., Kenyon, .A. T., and Koch, F. C., J . Clin. Invest., 16, 695 (1937). (7) Gibson, J. G., 2nd, and Evans, W. A , , Jr., Ihid., 16,301 (1937). (8) Girard, and Sandulesco, G., Helu. Chim. *4cta, 19, 1095 (6)
Recovery
%
(1936).
Holtorff, A. F., and Koch, F. C., J . B i d . Chrm., 135, 377 (1940). (10) Kinsella, R. A , Jr., Doisy, R. J., and Glick, J. H., J r . , Federation (9)
Proc., 9, 190 (1950). ill)
Lieberman, S., Fukushima, D. K., and Dohriner, K.. J . B i d .
(12) (13) (14)
Mellon, >I. G., A x . 4 ~ CHEM., . 21, 3 (1948). Xathanson, I. T., and Wilson, H., EndOCrilLOlOgy, 33, 189 (1943). Paschkis, K. E., Cantarow, A , , Rakoff. .\. E., Hansen, L., and Walkling, .1.A., Proc. SOC.Ezptl. B i d . &Wed.,53, 127 (1944). I’iiicus, G., J . Clin. Endocrind., 5, 291 (19463. Talbot, S . B., Berman, R. .4.,and MacLachlan, E. A , .I. B i d .
Civm., 182, 299 (1950).
DISCUSSION
The two principal limitations of a method for determiiiing iieutral 17-ketosteroids are that this group includes many substances (11) which are measured against one standard substance, and that acid hydrolysis has its shortcomings. To determine the individual substances requires an elaborate separation. Enzymatic hydrolysis, which is being carefully studied ( 2 , 4 , IO),should presumably eliminate errors due t o protein and bile salts, inasmuch as the authors find that these are introduced during boiling with acid. It wilI, howevcr, require enzyme preparations which hydrolyze glycuronides, sulfates, and possibly other conjugates. For routine clinical use, a procedure of the present type, with rigidly controlled conditions, may have to suffice for some time.
(15) (16)
Chem., 143,211 (1942). (17) Talbot, N. B., Ryan, J., and Wolfe, J. K., Ihid., 148, 593 (1943). (18) Wilson, C., and Holiday, E. R., Biochnin. ,I., 27, 1096 (1933). (19) Windaus, A, Ber., 42, 238 (1909). Z. physiol. Chcrir., 233, 257 (1935). (20) Zininiermann, W., RECEIVED hIay 24, 1950. Presented in part before the Division of Biological CHE~IICA SO L C I ~ Y ,DeChemistry a t the 117th Meeting of the AMERICAX troit, Mich. D a t a in this paper are taken f r o m the analytical section of a dissertation submitted to the Graduate Council of Wayne University by William T. Beher in partial fulfillment of the requirements for the degree of doctor of Iihilosophy in chemistry.
Determination of Selenium in Metallic Copper and Pyritic Materials J. S. McNULTY, E. J. CENTER,
AND R. M. MACINTOSH1 Battelle Memorial Institute, Columbus, Ohio
T
HE importance of a rapid method for the determination of selenium in metallic copper and copper pyrite became evident during metallurgical research in the treatment of copperbearing materials. A method utilizing small samples was of most interest. The gravimetric methods proposed by Scott ( 7 ) required excessively large samples and w x e too time-consuming. The method proposed by Evans ( I ) , based on the separation of selenium, tellurium, and arsenic from copper with sodium hypophosphite, showed some promise in the authors’ hands. 1
Present address, Tin Research Institute, Columbus, Ohio.
The proposed method consists of a modification of the dissolution technique of Evans, distillation of the selenium as the tetrabromide, and an altered volumetric finish outlined by McNulty ( 4 ) . The method is simple and reasonably accurate in the presence of impurities generally found in copper-bearing materials. EXPERIMENTAL
Effect of Sulfuric Acid-Copper Ratio on Selenium Recovery. Possible loss of selenium during dissolution and dehydration of
ANALYTICAL CHEMISTRY
124
During research on the metallurgy of copper, the need developed for a fast method of determining selenium in small samples. Conditions were found for quantitatively separating selenium from copper by distillation. By thus substituting one vapor-phase separation for one or two precipitations, the elapsed time required to analyze a sample was shortened. With little modification, this method can be economically applied to metals and minerals currently being analyzed by procedures involving separation by precipitation.
the sample w m investigated in a series of tests. Knonn quantities of selenious acid were added to electrolytic copper arid sulfuric acid in various proportions, and the selenium recovery was determined after dehydration and distillation. The result? arc1 given in Table I. About 15% of the selenium is lost if thr volunie-weight ratio of sulfuric acid to copper is onlv 5.5 to 1, and about 9% is lost if the ratio is 10.5 to 1. However, if the ratio of acid to copper is 21 t o I , the loss of selenium is ahout 2%. .A small amount of perchloric acid (1 ml.) was added t o each
Interfering Elements. Hoffman and Lundell ( 2 ) observed that arsenic, antimony, and tellurium dibtill with selenium a t 129" C. from a hydrobromic acid solution containing sulfuric acid. Jennison ( 3 ) showed that the masimum amount of these elements likely to be present in ordinary copper metal would be 0.04% arsenic, 0.003% antimony, and 0.003% tellurium. Synthetic standards were prepared containing up to tcln times the amount of impurities likely t o be present in commercial copper metals.
sample t o prevent deposition of elemrlntal selrnium during diqtillation.
Table I. Teet
KO.
Effect of Sulfuric Acid-Copper R a t i o on Selenium Recovery
Xeight of Volume of Copr)er H2804 M1, G. 10 55 55 10 55 10 10 105 105 10 105 10 5 105 5 105 5 105
Seienmm Added
Selenium Recovered
."Io. 1.50
1 .oo 0.50 1.50 1.00 0.50 1.50 1.00 0.50
Recoverv of Additlbe Selenium
.ua.
k
1.29 0.85 0.43 1.39 0.90
86 85
86 93 90 92 99 99 98
0.46
1.48 0.99 0.49
Selenium Recovery from Synthetic Samples. Using electrolytic copper as the base material, a series of tests was made with additions of selenium from 0.002 to 0.03%. .4 ratio of 21 ml. of sulfuric acid to 1 gram of copper was used in all twts during the digestion of the samples. A series of tests was also made using cupric sulfide as the base material. Slightly higher concentrations of selenium, 0.0125 to 0.0375%, were added in these tests. The results presented in Table I1 show that the loss uf selenium is well within the experimcnt:rl limits for both coppcr metal and sulfide samples.
Table 11.
Test NO.
1
2 3 4 5 6
7 8 9 10 11
12 13 14 1.5
16 17
1s
Selenium Recovery from Synthetic Samples
Base Material Electrolytic copper Electrolytic copper Electrolytic copper Electrolytic copper Electrolytic copper Electrolytic copper Electrolytic copper Electrolytic copper Electrolytic copper Electrolytic copper Electrolytic copper Electrolytic copper Cupric sulfide Cupric sulfide Cupric sulfide Cupric sulfide Cupric sulfide Cupric sulfide
Added
I'oiind
niiini
G.
M1.
% '
7%
%
5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 4.0 4.0 4.0 4.0 4.0 4.0
105 105 105 105 105 105 10.5 105 103 105 105 105 105 105 103 105 105 105
0.0020 0.0020 0.0040 0.0040 0.0060 0.0060 0.0100 0.0100 0.0200 0.0200 0.0300 0.0300 0.0125 0.0125 0.0250 0.0250 0.0375 0.0375
0.0019 0.0020 0.0041 0.0041 0.0060 0.0057 0.0008 0.0097 0,0195 0.0195 0,0292 0,0292 0.0124 0.0124 0.0248 0.0247 0.0373 0.0371
95 100 108 103 100 95 98 97 98 98 97 97 99 99 99 99 99 99
-
Figure 1.
Digestion Flask Distillation Head
L,
\
and
The results shown in Table I11 indicate that the tolerablr limit of arscbnic is in the region of 0.05%, the results being 12% high if 0.4% arsenic is added. The presence of 0.03% antimony or tellurium affects the results only slightly. Interfrrence of copper, introduced as spray during distillation, is prevcinted by the addition of potasrium cobalticyariide to the solution before titration ( 1 ) . PROCEDURE
Apparatus. The apparatus (4-6) consists essentially of a 275ml. Johnson flask and distillation head ( E , Figure 1). Several assemblies may be conveniently operated at one time. Dissolution and Digestion. COPPER METAL. Weigh 5 0 grams of sample into a Johnson flask, and add 30 ml. of water, 5 ml. of concentrated sulfuric acid, and 25 ml. of concentrated nitric acid When dissolution is complete, boil t o expel nitrogen dioxide. Cool the solution and add 100 ml. of concentrated sulfuric acid. Evaporate the solution and fume a t 190" C. until the precipitated cupric sulfate becomes gray in color. Cool, and add 1.0 ml. of perchloric acid (600/0) and 10 ml. of water. SVLFIDEMIXERALS.Transfer 4.0 grams of sample into a Johnson flask, and add 15 ml. of water and 50 ml. of concentrated nitric acid. When the reaction subsides, slowly introduce 50 ml. of concentrated sulfuric acid. Heat just below the boiling
V O L U M E 23, NO. 1, J A N U A R Y 1 9 5 1 Table 111.
Test NO.
Effect of ~ ~Antimony, ~ and~ ~ on Selenium Recovery Element -4dded
Element Added
brsenic llrsenic -4rsenic Arsenic Arsenic Arsenic Arsenic .4ntiinony -4ntimony .Intimony Antimony Antiinony ‘I’ellurium Tellurium Tellurium
0.04 0.04 0.04 0.40 0.40 0.40
Selenium Added
% 1 2 3
2 6 7 8 !4
10 11 12
13 14 15
% 0.0100 0.0100 0.0100 0.0100 0 0100 0.0100 0.0100 0.0100 0.0100 0 0100 0.0100 0.0100 0.0100 0.0100 0.0100
0.40
0.003 0.003 0.030 0 030 0.030 0.003 0.003 0.030
StarchIodide Reagent Added MI.
5 I 5 2 1
!
5
125 ~ ~l
Selenium Found
% 0.0102 0.0102 0.0100 0.0123 0.0114 0.0110 0.0113 0.0100 0 0100
1
0.0109
1
0.0103 0,0102 0.0100 0.0100 0.0102
1 1
?
l
during the distillation and reprecipitate when the hydrobromic ~iacid~is expelled. i~ ~ , , The ~ air-inlet hose should be provided with a bleeder to prevent possible suck-back of distillate. Titration. Remove the receiving beaker from the distillation assembly, and add 2.5 ml. of 90% formic acid and approximat.ely 3 grams of urea. Heat to dispel bromine. Neutralize with sodium hydroxide (1 pound per liter of water), using phenolphthalein indicator. Add 13 ml. of 18 N sulfuric acid and 2 ml. of 6% potassium cobalticyanide and cool the solut,ion to 20” C. Add 5 ml. of starch-iodide reagent (1 gram of potassium iodide in 100 ml. of 0.1% wheat starch paste) and titrate immediately wit,h 0.005 to 0.01 1%’ sodium thiosulfate solution. The end point is indicated by a color change from violet to pink which persists a t least seven seconds. Standardize t.he sodium thiosulfate solution against a selenite or selenious acid solution carried through all the steps leading to the titrat,ion. Run a reagent blank to establish the purity of new lots of chemicals. CONCLUSIONS
point to dissolvr any residual sulfur. Evaporate as described for copper metal, cool, and add 1.0 ml. of perchloric acid (60%) and 5 ml. of water. Distillation. Assemble the digestion flask and distillation head after coat,ing the ground joints with silicone grease. Clamp the neck of the flask to a ring stand or place in a special rack, allowing space for a Bunsen burner below the flask. Immerse the outlet, L , in 50 ml. of 0.170 aqueous hydrazine sulfate solution contained in a 250-ml. Bereelius beaker. Cool the beaker in a 6-inch evaporat.ing dish containing cold water. With the stopcock closed, introduce compressed air (or carbon dioxide) into tube J, a t such a rate that 2 o r 3 bubbles per second rise from L. Introduce 5 ml. of 48% hydrobromic acid into the sample through the funncl, I . Heat the flask gently with the Bunsen burner. Withdraw bromine vapor from the surface of the covered receiving beaker by means of a hooked glass tube connected to a water aspirator. When the solution in the flask becomes green, increase the flame and start 10 ml. of hydrobromic acid flowing into the eamplc a t the rate of 0.75 to 1 .O ml. per minute, keepin! the solution dark green. Maintain a vapor temperature of 123 to 130” C. Heat the thermometer well, E , occasionally t o remove condensate. The precipitate of copper sulfate will dissolve
Tiic method dcscrihcd is successfully used in the analyscs of copper bullion, mattes, and pyritic samples. The accuracy and reproducibility of the results are within the acceptable limits for control work. To avoid possible loss of a small amount of selenium, care should he taken not to fume the samples unnecessarilp during digestion. LITERATURE CITED
Y., Analyst, 67, 346-51 (1942). (2) Hoffman, J. I., and Lundell, G. E. F., J . Research Natl. Bur. Standards, 22, 465-70 (1939). (3) Jennison, H. C., and Smith, C . S., “Metals Handbook,” pp. 1389-95, Cleveland, Ohio, Ainericsn Society for Metals, 1939. (4) McNulty, J. S.,ANAL.CHEM.,19, 809-10 (1947). (5) Pavlish, A. E., and Silverthorn, R. IT., J . Am. Ceram. Soc., 23, 11+18 (1940). (6) Scherrer, J. A., J . Research S a t l . Bur. Standards, 16, 253-9 (1936). (7) Scott, W. IV., “Standard Methods of Chemical Analysis,” 5th ed., pp. 388-9, New York, D. Van Nostrand Co., 1939. ( 1 ) Evans, R.
RECEIVED .4ugust 8,
1950.
Impurities in Catalyst Materials Quanti t a t ive Spec t roscop ic A nalys is Usi ng A 1te r na t i ng Cu r re nt Spark DUANE D. HARMON
AND
RAYAMONDG . RUSSELL, Gulf Research & Development
co.,Pittsburgh, Pa.
The use of catalysts requires constant checking on the catalytic activity and the content of certain of the inorganic ions present. A method of checking that was quick and reasonably accurate was desired. -4 spectrographic method has been developed which will give results precise to within *loyo of the amount present of any of the desired cations. This method has been applied to the determination of iron, vanadium, nickel, and sodium in catalyst materials, the entire analysis taking less than 4 hours for a group of samples. This method should be applicable to any nonmetallic sample which can be put in powdered form. I t will give more information in a s h r t e r time than is possible by ordinary chemical methods. It utilizes the alternating current spark form of excitation and a briquetted pellet.
M
A N Y catalyst materials used in the oil industry are composed of an aluminum silicate matrix containing several minor impurities. During the life of the catalyst its activity decreases to the point where it is no longer economically feasible to continue its use, and a t the same time an increase in metallic impurities occurs. This “pickup” can be attributed either t o the metals present in the oil, or to the equipment used to handle the catalyst.
To determine these impurities by wet chemical methods is laborious and time-consuming, and the chemical determination of elements present in amounts less than 0.1% is relatively inaccurate. Inasmuch as spectrographic methods are usually more rapid and more accurate in these ranges, a spectrochemical method was developed for iron, nickel, vanadium, and sodium which were elements of particular interest a t this time. Several methods have been proposed for the analysis of im-
