probably largely responsible for the relatively small influence of matrix variations on the analytical results. It is also probable that the direct current arc promotes fusion of the sample-internal standard mixture, thereby incorporating the cobaltic oxide into a new glasslike structure of similar physical form for all samples. This is a great aid in improving the efficiency of the internal standard. ACKNOWLEDGMENT
The author thanks G. A. Simmons who first suggested that this work be undertaken. His constructive com-
ments in the preparation of the paper have also been helpful. The author is likewise indebted to W. P. Myers who performed all the wet analyses reported here. LITERATURE CITED
(1) Ahrens, L. H., “Quantitative Spec-
trochemical Analysis of Silicates,” Pergamon Press, London, 1954. (2) Churchill, J. R., IND.ENG.CHEM., ANAL. ED.16.653 .~ - - 119441. (3) Dennen, W. H., Ahrens, L. H., Fairbairn, H. W.,U. s. Geol. Survey, Bull. 980, 25-5?(( 1951). (4) Harrison, G. R., MIT Wavelength Tables,” Wiley, New York, 1939. ~
~~
I
\----,
( 5 ) Hasler, M. F., Harvey, C. E., Barley,
F. W., Am. SOC. Testing Materials, Proc. 48, 944 (1948). (6) Jaycox, E. K., ANAL. CHEM. 27, 347-50 119551.
(7) Lounamaa, N.,’Spectrochim. Acta 7, 358-66 (1956).
(8) Moore, C. E., Natl. Bur. Standards (U. S.), Circ. 488, Sect. 1, 30
(1950). (9) Ibid., Sect. 2, 64 (1952). (10) Price, W. J , Spectrochim. Acta 6,26 f1953).
(11) Wainer,’ E., Dubois, E. M., Am. Ceram. Soc. Bull. 20,4-7 (1941). (12) Zander, J M., Terry, J. H., J . Am. Ceram. SOC.30, 366-70 (1947).
RECEIVED for review October 31, 1956. Accepted February 11, 1957.
Determination of Zirconium in Steel Direct Spectrophotometric Method RICHARD B. HAHN and JACK L. JOHNSON Chemistry Department, Wayne State University, Detroit 7 , Mich.
b A
direct spectrophotometric method for the determination of small amounts of zirconium in steels is described. After removing interfering ions by electrolysis with a mercury cathode, the zirconium is determined by measuring the absorbance of its chloranilate complex a t 550 or 330 mp. Results by this method compare favorably with those by the p-dimethylaminoazobenzenearsonic acid and mandelic acid methods.
C
methods for zirconium usually involve the formation of lakes (1,2,6) or rely upon absorbance measurements obtained by dissolving a precipitate (4,s). Neither method is entirely satisfactory. Lakes are affected adversely by the presence of impurities. Indirect methods are empirical and results must be obtained by comparison with standard samples of similar coniposition (4). Thamer and Voigt (9,10) showed that zirconium ions in perchloric acid solution form soluble, colored complexes with chloranilic acid and used this as a colorimetric method for the determination of small amounts of zirconium. Absorbance was measured at 330 mp. Frost-Jones and Yardley (3) also studied the chloranilic acid method but measured the absorbance a t 525 mp. The sensitivity was less a t this wave length, but larger amounts of zirconium could 902
OLORISIETRIC
ANALYTICAL CHEMISTRY
be determined than by the method of Thamer and Voigt. As these methods involve the direct measurement of a stable, soluble complex of zirconium, they were investigated for the determination of zirconium in steel. The major obstacle is using the chloranilic acid method for the determination of zirconium in steel is the interference caused by the ferric ion. Ferric ions form a dark-colored complex with chloranilic acid which absorbs strongly in both the visible and ultraviolet regions. Attempts to eliminate this interference by reducing iron(II1) to iron(I1) were unsuccessful. Complete reduction could not be attained by using hydrazine or hydroxylamine. Sulfites, dithionites, and other sulfur-containing compounds gave low results. Ascorbic acid formed complexes which absorbed. Heterogeneous reductants-for example, zinc metal-were unsuccessful because the solution became reoxidized immediately upon removal of the reductant. Separation methods were tried. Ether extractions did not remove the iron completely. As electrolysis with a mercury cathode using a Melaven cell gave excellent separations, this was adopted as the method for removing interfering ions. After electrolysis, chloranilic acid was used to determine the zirconium remaining in solution. Very small amounts of zirconium (O.lyo or less) could be determined most accu-
rately by measuring the absorbance a t 330 mp, whereas larger amounts gave better results a t 526 mp. Therefore two procedures were devised. If the range of zirconium in the sample is unknown, measurement a t 525 mp is recommended. PROCEDURE
Reagents. Chloranilic acid (available from Eastman Kodak Co.): 0.1% solution, dissolve 1 gram of ABSORBANCE AT 525 my
1 Figure 1. Standard curve for spectrophotometric measurement of absorbance of zirconium at 525 mp
chloranilic acid in 1 liter of distilled mater; 2 X lO-4M solution, dissolve 0.042 gram of chloranilic acid in 1 liter of dis6lled water. Perchloric acid., 72% ,”, G. F. Smith Chemical Co. Method A. Samples Containing 0.1% Zirconium or More. Weigh a 0.2- to 0.5-gram sample of steel and dissolve in about 20 ml. of 6 M hydrochloric acid. Warm, if necessary. Add 7 ml. of 7 2 7 , perchloric acid and evaporate until copious fumes of perchloric acid are obtained. Dilute to about 20 ml. with water and electrolyze, using a mercury cathode in a hlelaven cell ( 7 ) , with stirring, for 50 minutes using a current of 0.5 ampere. Transfer the solution to a 100ml. volumetric flask, add 8 ml. of 0.1% chloranilic acid and 5 ml. of $27, perchloric acid, then bring up to volume with distilled water. Measure the absorbance a t 525 nip using a 5-cni. cell. Determine the amount of zirconium from the standard curve (Figure 1). Method B. Samples Containing Less than 0.17, Zirconium. Weigh a 1.0- to 5.0-gram sample of the steel and dissolve in 25 t o 50 ml. of 6 M hydrochloric acid, heating if necessary. Add 46 ml. of 7 2 7 , perchloric acid and evaporate to copious fumes of perchloric acid. Transfer to a 500-ml. volumetric flask and dilute to volume with distilled water. Take a 25-ml. aliquot and electrolyze as directed in Procedure A. Transfer the resulting solution to a 100-ml. volumetric flask, add 10 ml. of 72% perchloric acid and 13 ml. of 2 X l0-4M chloranilic acid, then dilute to volume with distilled water. Measure the absorbance a t 330 mp using a 1-em. quartz cell. Determine the amount of zirconium from the standard curve (Figure 2).
Table II. Zirconium in Nickel-Chromium Steels (Per cent zirconium) Chloranilic Acid, Method B (Absorbance Read at 330 M p ) Sample 1 Sample 2 Sample 3 0 028 0 033 0 035 0 036 0 045 0 053 0 042 0 040 0 037 0 OOi3 0 0043 0 0074
Steel NO.
307-4 307-5 307-6 T-1755
Table I.
Ion Sod-c1Ti +4 Fe+i+ Nb +5 WOa--
Effect of Diverse Ions Times Greater Amount than Tolerated, Zirconium Mg./lOO pl1l.a Concn. 200 20 5000 500 10
0.5
1 .o
100
5
10
0.5 5 F0.1 1 Amount that causes an error of 3% in determination of zirconium. 5
0 040
0 006
Table 111.
Zirconium in Simple Carbon Steels Per Cent Zirconium Colorimetric, Colorimetric, Mandelic 330 mp 525 mp acid ~
Steel SO.
1 2 3
0.008
0,008
TL72802
0 022
0.018
r---l
0 090 0 160
ABSORBANCE AT 330
s o ppt.
0.108 0.221
my
0.110 0 220 0 025
Phosphate method 0,025 0.20 0.34 0 05
The zirconium content of simple carbon steels mas determined by the chloranilic acid method using Procedures A and B. These determinations compared ivith results obtained from the mandelic acid method (5) and the phosphate method are given in Table 111. These data indicate substantial agreement between both chloranilic acid methods and the mandelic acid method. Results from the phosphate method are high. As mandelic acid is a more specific precipitant for zirconium than the phosphate ion, the high results in the phosphate method are caused by coprecipitation of impurities. ACKNOWLEDGMENT
DISCUSSION
The method was tested first on “synthetic” steels obtained by adding known amounts of standard zirconium perchlorate solution t o a solution of ferric perchlorate. These solutions were electrolyzed and the zirconium content was determined. Quantitative recovery of the zirconium was obtained in all experiments. The interference of various ions was
.Iv. 0 032 0 045
Haves and Jones Method 0 02 0 03 0 05 0 003
Figure 2. Standard curve for spectrophotometric measurement of absorbance of zirconium a t 330 m p
The authors wish to thank E. D. AIartin, Inland Steel Co., and Kenneth L. Proctor, Philadelphia Naval Shipyard, for supplying steel samples used in this investigation. LITERATURE CITED
studied. Varying amounts of foreign ions were added to solutions containing known amounts of zirconium and determinations mere made, without electrolysis, a t both 525 and 330 mp. Interferences were the same a t both wave lengths (Table I). The effect of various other foreign ions is given by Thamer and Voigt (9). The effect of varying the concentration of perchloric acid was studied. Quantitative results were obtained in solutions 1.5 to 2.5M in perchloric acid. Acid concentrations lower than 1.5M gave high results for zirconium, whereas concentrations greater than 2.5M gave low results. The method was tested also using nickel-chromium steels whose zirconium had been determined by the method of Hayes and Jones (4) (Table 11).
(1) Boer, J. H. de, Chem. Weekblad 21, 404 f 1924). ( 2 ) Charonant, ’R., Cornpt. r a d . 199,
1620-2 (1934). (3) Frost-Jones, R. E. U., Yardley, J. T.., A n ~ l y 7~7t, 468-72 (1952). (4) Hayes, Vir. G., Jones, E. W., IND. ENG. CaEx.. AXAL. Ed.,, 13,. 603-4 (1941).’ (5) Kumins, Charles, Ibid., 19, 376 ( 1 947). -\ - -
(6) Liebhafsky, H. A., Winslow, E. H., J . Am. Chem. Soc.,. 60, . 1776-84 (1938). (7) Melaven, A. D., IND.ENG.CHEM., AKAL.ED.,2 , 180 (1930). (8) Nazarenko, V. A., J . Appl. Chem. IlJ.S.S.R.’, 10. 1696-9 11937). (9) Thamer, B. J., Voigt, A.‘F., J . Am. Chem. SOC.73,3197-202 (1951). (10) Thamer, B . J., Voigt, A. F., J . Phys. Chem. 56, 225-32 (1952). RECEIVED for review October 29, 1956. Accepted December 10, 1956. Division of Analytical Chemistry, 130thbleeting,ACS, Atlantic City, N. J., September 1956. VOL. 29, NO. 6, JUNE 1957
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