172
ANALYTICAL CHEMISTRY
Table 11. Effect of Final p H on Coprecipitation of ,Manganese
a
Manganese Coprecipitateda Final pH Mg. 1.31 1.79 1,33 1.65 1.42 1.89 1.52 1.88 1.57 1.96 1.58 1.90 1.62 1.95 1.64 1.80 1.75 1.90 273 mg. of tin present: 100 mg. of manganese added
and dissolved and manganese was determined by the periodate method of Willard and Greathouse ( 4 ) . Nickel. The precipitate was ignited and then transferred to an iron crucible and fused with sodium hydroxide containing a small amount of persulfate. The melt was then dissolved in water and the precipitate was filtered, washed, and dissolved, and nickel was gravimetrically determined with dimethylglyoxime. Iron. The basic stannic sulfate precipitate was treated as described for manganese. Iron hydroxide was subsequently separated and dissolved in 25% hydrochloric acid and comparisons were made with similarly constituted standards, using a photoelectric colorimeter. DISCUSSION O F RESULTS
The adherent film, in the case of manganese as indicated in Table I, contains about 0.1 mg. of manganese, As previously described, the adherent film less accompanying silica weighed approximately 18 mg. The ratio of tin to manganese is thus 180 as compared to about 140 for the precipitate itself. While the evidence is not conclusive, since the xeight of the film is only approximate, it furnishes some indication that the film preferentially substitutes the beaker surface for the coprecipitated element. Except in the rxpPrinicnts cvitcd in Table I , analyses of films vere not made, so that all coprecipitation data refer to the element determined in the precipitate. The reproducibility of the data is well shown in analyses for manganese content of the precipitates in the experiments ill Tables I and 11.
As indirated in the final washings in Table I, much of the coprecipitated element must be well imbedded within the precipitate since hot 2% ammonium nitrate solution, a t p H 1.5, failed to remove any measurable quantity of manganese. This is further indicated in Table 11, since there is no essential difference in the amounts of manganese coprecipitated within the p H range of 1.31 to 1.75. Since basic stannic sulfate is quantitatively precipitated a t p H 1.3 and manganese(I1) precipitates a t pH 8.5, it is somewhat Eurprising that a separation was not effected. The results for nickel were no better. Relatively more nickel was coprecipitated, as may be expected, since nickel(I1) precipitates a t pH 6.7. Iron is coprecipitated in relatively large amounts, but this should be expected since iron(II1) precipitates a t pH 2. The coprecipitation isotherms of Figure 3 nere obtained by a procedure different from that normally used in adsorption experiments with preformed carriers. Because of the relatively large amounts of coprecipitated metals and because of the adherent film, this method of precipitating tin(IV) from homogeneous solution does not allow its application to the determination of tin. This is unfortunate, since basic stannic sulfate appears to be the densest of all the basic salts produced by the urea method. From past experience it has been found that the denser the precipitate the more it adheres to the beaker. Basic stannic sulfate is no exception. However, these properties, undesirable in an analvtical procedure, make the precipitate useful as a carrier in the study of coprecipitation processes. LITERATURE CITED
(1) Gordon, L., A N ~ LCHEM., . 24, 459 (1952). (2) Weiser, H. B., “Inorganic Colloid Chemistry,” VoI. 11,pp. 23050, New York, John Wiley & Sons, 1935. (3) Willard, H. H., ANAL.CHEM.,22, 1372 (1950). (4) Willard, H. H., and Greathouse, L. H., J . Am. Chem. SOC.,39, 2366 (1917). RECEIVED for review J u n e 24, 1952. -4ccepted September 3, 1952. From a dissertation submitted b y Louis Gordon t o t h e Graduate School of the University of Michigan in partial fulfillment of t h e requirements for t h e degree of doctor of philosophy in chemistry.
Rapid Method for Determination of Urinary Fluorine RUSSELL F . MILLER AND PAUL H. PHILLIPS Department of Biochemistry, University of Wisconsin, Madison, Wis.
HE basic method for fluorine analysis is that of Willard and TWinter (6), which uses a perchloric acid distillation of an alkaline ashed sample. Several modifications of this procedure for the determination of fluorine have been made (I,.!-5). Although these methods are suitable for the determination of fluorine in urine, the preliminary alkaline ashing required in all these procedures is time-consuming for routine analysis. A simplified procedure for unashed samples has been developed which has given results comparable to those obtained with the ashing procedure. The essential features of the method are: a specific gravity determination was made on the urine sample with a hydrometer; and the sample was then diluted (1 to 15) iyith glass-redistilled water. A 25-ml. aliquot of diluted urine mas pipetted into the dietillation flask for direct distillation of the fluorine.
optimum. Solutions more concentrated than 1 part of urine to 10 parts of redistilled water were inclined to foam and froth, which rendered titration difficult. Likewise, fluorine recoveries from concentrated samples were less accurate. Twent five milliliters of the diluted urine was pipetted into the d i s t i l h o n flasks, and 2 ml. of silver perchlorate (1 gram per ml.) and several glass beads were added. Perchloric acid (25 ml. of 72y0 acid) was then added. Samples were steam distilled a t 135.5’ C. Following the distillation, the usual titration procedures were used. I t required in some cases 1 ml. of 0.05 N sodium hydroxide to bring the distillate into the proper pH range for titration. For calculation and comparative purposes, all samples were corrected for dilution and to a specific gravity of 1.04. For testing procedures, similar aliquots of both diluted and undiluted urine were ashed and analyzed by the method for fluorine determination as modified by the Aluminum Research Laboratories
FLUORINE DETERMINATION
A comparison of the fluorine content of unashed and ashed aliquots of urine is presented in Table I. Over a wide range of urinary fluorine concentrations the unashed diluted urine gave very acceptable values as compared to the sample treated in the normal manner, The data show that the values obtained by
A single sample of urine was collected from each cow and 500 ml. saved for analysis. The urine x a s stored in ground glassstoppered bottles. Specific gravity was determined by means of a hydrometer, and the sample diluted with 15 parts of redistilled water. I t was found that a dilution of 1 to 15 was near
(8). COiMPARlSON OF METHODS
V O L U M E 25, N O . 1, J A N U A R Y 1 9 5 3
173
Table I. Determination of Urinary Fluorine b y Standard and Modified Methods Ashed Samples Fluorine Av. fluorine range, recovered, p.p.m. p.p.m. 1.8-4.0 2.8 16.4-30 24.2 32-45 39.0 46-60 50.8
Unashed Samples Fluorine Av. fluorine' range, recovered, p.p.m. p.p.m. 1.4-3.6 2.5 15.3-30 22.7 30.4-48 39.4 42-57 48.7
No. of .4nalyses 7 12 11 10
Table 11. Recovery of Fluorine i n Ashed and Unashed Urine Samples Ashed Samples Fluorine Fluorine range, recovered, Y
Unashed Samples Fluorine Fluorine range, recovered,
96.3 102.5 100-107.5 103.8 Av. 100.8 Fluorine added, 100 micrograms. 100-105
a
Y
Ya
91.5-95 95-105 92.5-1 10
93.3 100 101.3 98.2
-fa
90.0-102.5
micrograms of added fluorine as sodium fluoride. It appears from the data in this table that there was good recovery of the added fluorine from either the ashed or the unashed sample of urine. Good recoveries were obtained with the nonashed sample, particularly where the amount of fluorine present exceeded concentrations of 10 p.p.m. LITERATURE CITED ( 1 ) Agate, J. N., Bell, G. H., Boddie, G. F., Bow-ler, R. G., Buckell, hf., Cheeseman, E. A , , Douglas, T. H. J., Druett, H. A.,
Garrad, J., Hunter, D., Perry, K. hI. A,, Richardson, J. D., and Keir, J. B. de V.,Medical Research Council, Great Britain, ll!femo. 22, 120 (1949). (2) Aluminum Co. of America, New Kensington, Pa., , illurninurn Research Laboratories, Tech. Paper 914 (1947). (3) Armstrong, W. D., IKD.ENG.CHEY.,ANAL.ED.,8, 384 (1936). (4) Blakemore, F., Bosworth, T. J., and Green, H. H., J . Comp. Path. Therap., 58, 267 (1948). ( 5 ) Clifford, P. A , , J . Assoc. Ofic.Agr. Chemists, 27, 248 (1948). ( 8 ) Willard, H. H., and Winter, 0. B., IND. ENG.CHEM., ANIL. ED., 5 , 7 (1933).
using an ashed sample compared with the nonashed sample are in fairly close agreement. There x-as agreement between these tm-o methods within 1 to 10%; the greatest deviation occurred with urines containing the smallest quantities of fluorine. Recovrry data in Table I1 indicate good recovery from 100
RECEIVF.D for review July 12, 1952. .Iccepted September 17, 195'2. P u b lished with the approval of the director of the Wisconsin Agricultural Experiment Station. Supported in part by a grant from the Aluminum Co. of America, Pittsburgh, P a . , on behalf of itself a n d American Smelting and Refining Co.. Kaiser riluminum and Chemical Corp., Monsanto Chemical Co.. Reynolds Metal Co., Tennessee Valley Authority, and United States Steel Corp. of Delaware.
Extraction of Aluminum Soap with Acetone KAROL J. MYSELS', HAROLD H. POMEROY2, AND GEROULD H. SMITH3 Stanford University, Calif. XTRACTION of aluminum soap with acetone is frequently used in commercial practice to determine the free or uncombined acid. It has also been used to determine the extent to which this acid is held by the soap (1, 2 ) and to prepare pure
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4
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0
acetone removes relatively rapidly the free and bound acids as shown by the rapidly rising initial part of tJhecurves of Figures 1, 2, and 3 and then causes slow hydrolysis of the soap as shown by the almost horizontal part of these curves. The rate of hydrolysis increases with temperature of extraction (Figure 1), R-ith moisture content of the acetone (Figure 2), and with the solubility of the fatty acid (Figure 3). Hence, by using carefully dried acetone and a low temperature, the extent of hydrolysis can be greatly reduced.
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1
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ACETONE, LITERWGRAM OF SOAP
Figure 1. Effect of Temperature of Extraction upon Composition of A l u m i n u m Soap Soxhlet-Extracted w i t h Acetone Dried over Drierite aluminum monohydroxy soap (6). The results of these procedures depend greatly on conditions. The purpose of this paper is to present some data clarifying the effect of these conditions. Anhydrous acetone would have no effect on aluminum soaps such as the hydroxy dilaurate, (RCO0)2Al(OH), but may dissolve any free acid present or that bound by solution, adsorption (a), or in acid soap (RC00)2AI(OH).HL ( 1 ) . However, anhydrous acetone is seldom, if ever, encountered ( 3 , 6) and ordinary dry acetone contains enough (0.3%) moisture in 1 liter to hydrolyze completely 37 grams of the soap. I n fact, extraction with 1
Present address, University of Southern California, Los Angeles, Calif, address, Merco Centrifugals, San Francisco, Calif. Present addresq, Union 011Co , Brea, Calif
* Present 8
0 EXTRLSTOH WE* 0 EXTRACTION OVER V EXTRACTION W E R 0 EXTRACTION WITH ACETWE
CAW, XIW, NA,W4
UNlXliED
That hydrolysis does not proceed a t a uniform rate through extraction is apparent from the fact that the almost horizontal portions of the curves do not extrapolate to the same intercept which would be the composition of original soap. The composition of this original unhydrolyzed soap may, hoKever, be obtained by plotting the intercepts obtained in Figures 1 and 2 against the
