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Table IV. Total Lead in Gasolines by Gas Chromatography and X-Ray Grams of lead per gallon Gas chroma-X-ray tography fluorescence Gasoline A 2.98 3.12 Gasoline B 0.45 0.50 Gasoline C 2.21 2.09 Gasoline D 2.91 2.76 isomers were not available. The isomer distribution specified by the manufacturer was assumed correct. Greater reliability in the accuracy of the results would be obtained by calibrating with the pure isomers.

The recoveries of 95 to 100% of theoretical include instrumental variations and the possibility of impurities in the commercial samples used as standards. Because of the unusual difficulties in maintaining constant operating conditions during a series of runs at reduced pressure, frequent calibrations or internal standards (6) should be employed. A routine method devised for the analysis of similar aromatic sulfonic acid mixtures gave results with a two sigma variation of 5% relative for the major component when a peak area method with internal standardization was employed. ACKNOWLEDGMENTThe author is indebted to W. A. Gregory for his helpful discussions on the conversion reactions, and to G. J. Wallace, who assisted in the experimental work.Certain samples of sulfonic acids used in this study were generously supplied by J. E. Callen of the Procter & Gamble Co., Cincinnati, Ohio.

GLC only. The data indicate that GLC results are somewhat more accurate when the MEG contents are higher.The DEG contents of several of the samples shown in Table II were also determined by the difference between periodate and dichromate titrations (1) and the results indicate that the dichromate method is not usable for determining DEG in this range.LITERATURE CITED(1) Porter, It. S..