b u t also permitted the detection of interferences other than those involved in direct precipitation with tetraphenylborate-e.g., Ag(1). It must be kept in mind that the final analytical data for potassium are a composite evaluation of the potassium method itself and of the simple procedure used to prepare the sample for measurement. There is no reaqon to doubt that better results would be obtained for potassium if more constituents of the sample were removed prior to the potassium nieasurement . Table VI1 summarizes the results for potassium in the various S B S samples which n ere decomposed and titrated as described. The reproducibility in samples containing more than 1% potassium is good; the accuracy is about the usual 1% (relative). K i t h mnple. containing less than 1y0potassium, the precision and accuracy are somenhat lesp. The latter effects may be due to interferences by some constituents prefeiit in the sample, \vhich become important Lvhen large amounts of sample, by necessity, are used. For example, when samples containing large percentages-e.g., 20 to 7070-of Al2O3 n ere analyzed, conkistently low results for potassium n ere obtained. These lou results may be due t o the occlusion or adsorption of potassium ion by hydrous aluminum oxide or Gimilar species formed when the pH is adjusted. Presumably, other constituents which form hydrous precipitates could h a r e the same effect nhen large samples are used. Removal of the precipitable constituent in part, if not entirely, would then improve the potafsium results. Besides potassium, the tetraphenylborate ion forms insoluble salts with ammonium, rubidium, cesium, thallium(I), silver, mercury(I1) ions, and many nitrogen bases, nhich constitute the major interferences to the method. ,4 precipitate is also produced with mercury(I), which may be a niivture of mercury and of niercury(I1) tetraphenylborate. Ammonium, silver, and mercury(I1) ions can be easily removed b y standard methods, and the others present no real difficulty because the amountq generally encountered are negligible. The present method proposed for potassium is equally applicable to determining the other species enumerated, provided that each compound Kith tetraphenylborate is sufficiently insoluble and precipitates sufficiently rapidly. Strong Oxidizing agents might interfere b y oxidizing the t e t r a p h e q lborate.
Table VII.
Determination of Potassium in National Bureau of Standards Samples
KZO, %
S B S Sample SO.
la 89
91
99 1 02
SBS 0,il (0.624. 78)“
Found
-
0.i9 0.85 Mean 0.82 8.40 8.37 (8.19-8.41)“ 8.39 8.46 8.32 3Iean and Etd. dev. 8.39 =k 0.064 ( i o .76%) 3.25 3.25 (3,21-3.51)a 3.36 3.30 Xean and Etd. dev. 3.30 ==! 0.055 (*1.7%) 0.41 0.35 (0.38-0.44)0 0.29 0.25 (0.264.31)n 0 33 hIean 0.29
a A4verageresults reported by different analysts. from nhich the SBY value rras computed, had range given in parentheses.
(21)Ridorff, IT-.,Zannier, H.,Ibid., 137, 1 (1952);Angezc. Chem. 64, 613 (1952). 122) Scholl, E.I],, iin-a~. CHEX 29, 1044
ACKNOWLEDGMENT
The authors wish t o t h a n k the U.S. Atomic Energy Commission, which helped support the n-ork d e s c r i b d
i19,5i).
LITERATURE CITED
W.R.,Sympson, R. F.. -A4ss..44 ~ . (1)A4mos,IT. CHEAT. 31,133(1959). 1(2) 2 ) Barnard. Barnard, A. A. J., J.. Jr.. Jr., Chemist Anaiii.ql Anai1pl44, 44. 104 (1955);45, 110 (1956). Biichl, H H.,, IILid., (3) Barnard, A. JJ.,, Jr., Buchl, Ld, 46, 16 (1957): (1957); 47, 46 (1958); 48, 44 (1958). (4) Cooper, S. S., ANAL. C‘HEV. C H ~ 29, . 446 (195i). (5) Crane, F. E., Jr., Ibid., 28, 1794 (1956); ,4nal. Chim. A c t a . 16, 3i0 (19671. (6)-Eiv{nnp, P. J., Krivis, .I F., . .49.41,. CHEAI. 30,1645 (19%). ( 7 ) Elving, P. J., Smith, D. L., unpublished data. (8) Elving, P. J., Smith, D. L., Jamieeon, D.R.. unuublished data. (9) Findeis,‘ il. F., DeVries, T.,.IYAL. CHEM.28,209(1956). (10)Ibid., p. 1899. (11) Flaschka, H., 2.anal. Chem. 136. 99 (1952). (12)Geske, D. H., J . Phys. Chem. 63, 1062 (1959). (13) Gloss, G. I%.,Chemist Analyst 42, 50 (1953). (14)Hahn, F. L., 2.anal. Chenz. 145, 97 (1955). (15)Heyrovsky, il Chem. Iisty 50, 69 (1956);52,40 (ldb8). (16) Kemula, W.,Lornacki, J., Rocznickz Chem. 28, 635 (1954). (17)Kirsten, W. J., Berggren, A., Nilsson, K., A N A L . C H E Y . 30,237 (1958). (18) Lane, E. S., Analyst 82,406 (1957). (19) Morris, J. B., Schempf, J. M., A x . 4 ~ . C H E M . 31,286 (1959). (20) Raff, P., Brotz, W.,2. anal. Chem. 133,241(1951).
123) Smith, Edward, Vniversity of Michigan. Ami :lrbor, IIich., private comniuiiicittion, 1960. (24) Spier, H. IT., Riochem. Z . 322, 467 (1952). (25) Spier, H. W.,Wagner, G., Klzn. Wochschr. 30. i5i (1952). (26) Sporek, L:, Killiams, A. F., Analyst 80,347(1955). ( 2 i ) Washington, H.S.,“Chemical ,Analrsie of Rocks,” 4th ed., pp. 220-2, Wiley, S e w York, 1930. 128) \Vittig, G.,IScicher, G., Ruckert, A., Raff, P., Ann. Cheni., Lzebigs 563, 110 I 1949)
R E C E I T E Ufor rrviely &lay 11, 1960 .lccrpted Jiine 30, 1960.
Correction Rad io metric Extract ion Method for Fluoride. Pyrolysis-Ion Exchange Separation I n this article by‘W. J. illaeck et al. CHEM. 32, 922 (1960)], On page 923, column 1, line 31, t h e sentence should read “Columns may be re-used b y passing 100 ml. of 6 N hydrochloric acid followed by 100 ml. of elutant through after each sample.” On page 924, last column of Table I, line 11, “oxide” should be “increase.” [-kh.AL.
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