IDENTIFICATION OF SURFACE ACTIVE AGENTS 793 active agent could be readily identified by its chromatogram, which was distinguishable from any other gylcol ester. Several sorbitan esters have been investigated by this technique. Figure 4 shows a comparison of the chromatograms for sorbitan mono- laurate (Arlacel 20) before and after trimethylsilylation. The Arlacel 20 is broken down into a large number of components. Peaks A and B represent the main components of free sorbitan. Peak A is probably the hexide or five-membered ring dehydration product of sorbitol. Peak B has been assigned as the hexitan or six-membered ring dehydration product. This pattern is repeated with some minor modifications in each of the sorbitan ester combinations. In the example shown, the fatty acid component is lauric acid. No attempts have been made thus far to make any definite assignments to these peaks. For the purpose of this investigation it is significant to note the differences among the sorbitan esters and use these data as a method of identification. The differences between Arlacels 20, 40, 60, and 80 are apparent after comparison of Figs. 5, 6, and 7 with Fig. 4. It is also apparent that this gas chromatographic method could be an important tool in the elucidation of the composition of these surface- active agents. Table I gives a listing of the relative retention times of the major peaks of each of the glycol esters and sorbitan esters run by this technique. In each case there is no problem in identification of the surface activ e agent from its definitive chromatogram. The trimethylsilylation reaction has also been applied to several other cosmetic raw matedhals. Figure 8 shows a chromatogram of lauric acid diethanolamide after trimethylsilylation. Peak A in this chromatogram is due to free diethanolamine, peak B to free lauric acid, and peak C (the main peak) to the amide. Peak D has been identified as the amine ester. The minor peaks have not been identified. Further investigation of this raw material may provide for identification of the amide ester that is usually present in this raw material. Possibly other more selective columns might perform an improved resolution job. The use of this technique for analysis of ethanolamines is another important application. The diethanolamine impurity gives an excellent peak (Fig. 8). Equally sharp, well resolved peaks are given by monoethanolamine and trietha- nolamine. SUMMARY The technique of tdhmethylsilylation followed by gas chromatography appears to be applicable to the identification of some non-ionic surface-

794 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS active agents. It has been found to be particularly useful for glycol esters and sorbitan esters. Some of the possibilities of extension of this work to quantitative analysis of the components of these surface-active agents has been mentioned. In addition, fatty amides and ethanola- mines have been indicated as areas of research that would merit further interest. (Received July 16, 1965) (i) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16) REFERENCES Hofmann, A. F., J. Lipid Res., 3,391 (1962). Hamilton, J. G. and Holman, T. T., J. Am. Chem. Soc., 76, 4107 (1954). Huebner, V. R., J. Am. Chem. Soc., 35,325 (1958). Holasek, A., and Fried, J., Mikrochim Acta, 1957, 469. Dieckert, J. W., and Reiser, R., J. Am. Oil Chem. Soc., 33, 123 (1956). Privett, O. S., and Blank, M. L., Ibid., 39,520 (1962). Rybecka, S. M., Chem. Ind. (London) 1962, 308. Vioque, E., and Holman, R. T., J. Am. Oil Chem. Soc., 39, 63 (1962). Perry, E. S., and Brokow, G. Y., Ibid., 32,652 (1955). Monick, J. A., and Treybal, R. E., Ibid., 3/!, 193 (1956). Fryer, F. H., Ormand, W. L., and Crump, G. B., Ibid., 37,589 (1960). McInnes, A. G., Tattrie, N.H., and Kater, M., Ibid., 37, 7 (1960). Huebner, V. R., Ibid., 36,262 (1959). Sweeley, C. C., Bentley, R., Makita, M., and Wells, W. W., J. Am. Chem. Soc., 85, 2497 (1903). Bentley, R., Sweeley, C. C., Makita, M., and Wells, W. W., Biochem. Biophys. Research Commun., 11, 14 (1963). Wood, R. D., Raju, P. K., and Reiser, R., J. Am. Chem. Soc., 42, 161 (1965). ERRATUM Due to language difficulties an unavoidable error occurred in the synopsis of "Approaches to a Prophylaxis of Skin Aging," by M. and H. Ippen, J. Soc. Cosmetic Chemists, 16, 305-8 (1965). The corrected synopsis should read as follows: Synopsis--It is shown that smoking has a deleterious effect on skin condition and that this effect can be differentiated from that of damage by sunlight. Smoker's skin is identified as skin which suffers from loss of "turgor" and shows signs of flabbincss in addition, the color of the smoker's skin is pale, with a grayish hue. Dermatological examination of 224 women up to now show moderate correlation between their smoking habits and the appear- ance of their skin, as defined above. By contrast, smoking seems to have only a very minor effect on the skin of male smokers. For the convenience of the readers, the corrected synopsis is repeated on page xxxvii for use in card indexes.