CHROMATOGRAPHY AND ITS APPLICATION 27 Using the "chromatostrip" technique, the 2,4-dinitrophenylhydrazone and semicarbazone derivatives of aldehydes and ketones, and the 3,5-dini- trobenzoate and carbamate derivatives of alcohols were separated using an appropriate solvent in each case. Many investigators have separated the 2,4-dinitrophenylhydrazones of aldehydes and ketones. Using a silica gel-bentonite column, Braddock, et aL (20), were able to separate the cis and trans forms of furfuraL2,4- dinitrophenylhydrazone. White (21), using a similar column and a sol- vent mixture of 75% hexane in ethyl ether, separated 18 pairs of mixtures, representing 12 aldehydes and ketones. He applied this technique to the chromic acid oxidation of crude 2-ethyl butanol. When the crude mixture of the 2,4-dinitrophenylhydrazones was chromatographed, six bands were observed of which the upper two were predominant. The first band yielded the 2,4-dinitrophenylhydrazone of diethyl ketone (identified by its melting point) the lower band, after readsorption, yielded the 2,4-dinitrophenyl- hydrazone of 2-ethyl butyraldehyde. Sorm (22) separated the 2,4- dinitrophenylhydrazones of some volatile aldehydes on a freshly precipi- tated calcium sulfate column, using petroleum ether as the eluting solvent. Rosen (23) used a silicic acid-celite column and benzene as the solvent, in the attempt to resolve 91 pairs of 14 aldehydes and ketones. He was successful in separating 77 pairs. Meigh (24) separated the 2,4-dinitrophenylhydrazones of volatile alde- hydes on paper, using methyl alcohol-heptane as the solvent, and devel- oped the spots by spraying with 10% NaOH. Paper chromatography was used by Uno (25) to separate the benzene-sulfohydroxamic acid deriv- atives of C-1 to C-5 aldehydes using iso-amyl alcohol:acetic acid:water (5:1: 1) as the solvent. A great deal of work has been done on the resolution of the derivatives of alcohols. Siegel, et aL (26), separated the reaction product of mono- hydric alcohols with 3-nitrophthalic anhydride on paper using iso-amyl alcohol-concd. NH4OH-water (30:15:5), as the solvent, and identified them with umbelliferone under ultraviolet light. Momose, et aL (27), used 3,5- dinitrophthalic anhydride to form the acid esters with both lower and higher alcohols and separated them on paper, using butanol saturated with acetic acid and butanol-acetic acid-water (8:1:2), respectively, as the solvents. The spots were detected by first spraying with NaOH and then with aceto- acetic ester, to yield orange-red spots. The resolution of the 3,5-dinitro- benzoates of alcohols on paper has been effected by Rice, et aL (28), and Meigh (29), and on columns by Holley and Holley (30), and White, et aL (31). Kariyone, et aL (32), separated the potassium xanthogenates on paper. Davenport and Sutherland (33), prepared the phenylazophenyl- urethans of terpene alcohols and separated them on an alumina column, identifying them by their melting points.

28 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS The chromatography of organic acids has been investigated thoroughly by numerous authors. However, I would like to cite some examples. Pearl and Beyer (34) separated and recovered, quantitatively, vanillic and protocatechuic acids on a Magnesol © column, using benzene-ethyl alcohol (20: 1) as the solvent. Marvel and Rands (35) were able to resolve o, m, and p-hydroxybenzoic acids on a silicic acid column, using progres- sively more polar solvents of chloroform and n-butanol. The detection of adulterants is of interest to our industry. There is no pr. ocedure for the detection of ethyl vanillin in a vanilla extract in the "Methods of Analysis" of the Association of Official Agricultu•'al Chemists. However, Way and Gailey (36) separated these two components on W•atma•n No. 1 paper, using n-butanol saturated with ammonia as the sol- vent, and detected them with an aqueous hydrochloric acid solution of 2,4-dinitrophenylhydrazine. They were able to quantize this procedure by eluting the cut-out area of a pilot strip and determining the concentra- tion with a Beckman spectrophotometer. Vitte, et al. (37), also separated the above mixture and identified the spots by spraying with a silver nitrate solution and heating to 110 ø. I have purposely not mentioned the use of chromatography in the de- termination of proteins and amino acids, sugars, and inorganic elements, because they are of little interest to our industries. In conclusion then, chromatography is being used and could be used to good advantage by the cosmetic and essential oil industries, for the prep- aration of pure compounds, the analysis of complex mixtures, for control purposes, and for the detection of adulteration. I do hope that, in present- ing this material, I have been able to introduce to you the value of chroma- tography and some of its applications. REFERENCES (1) Rose, A., Atnal. Chem., 22, 1369 (1950). (2) Weissberger, A., editor, "Technique of Organic Chemistry," Vol. IV, "Distillation," New York, Interscience Publishers (1951). (3) Winsten, W. A., and Eigen, E., )t. Arm. Chem. Soc., 70, 3333 (1948). (4) Dent, C. E., Biochem. )t., 4:3, 169 (1948). (5) Martin, A. J.P., and Synge, R. M. L., Ibid., :35, 1358 (1941). (6) Consden, R., Gordon, A. H., and Martin, A. J.P., Ibid., 41, 590 (1947). (7) Miiller, R. H., and Clegg, D. L., Atnal. Chem., 2:3, 396-411 (1950). (8) D•shusses, J., and Desbaumes, P., Mitt. Gebiete Lebensm. u. Hyg., 4:3, 501-541 (1952). (9) Weiss, L. i•., )t. Atssoc. O•qcial Atgr. Chemists, 34, 453459 (1951). (10) Tilden, D. H., Ibid., :35, 423 (1952). III Vanden Heuvel, F. A., and Hayes, E. R., Atnal. Chem., 24, 960 (1952). (13) Leone, E., and Guerritore, D., Boll. soc. ital. bioL spec., 26, 608-609 (1950). (14) Kurtz, F. E., )t. Arm. Chem. Soc., 74, 1902-1909 (1952). (15) V61on, P., and Medynski, G., Ind. De la Parrum., 7, 198-200 (1952). (16) Kirchner, J. G., Miller, J. M., and Keller, G. J., Atnal. Chem., 2:3, 420 (1951). (17) Miller, J. M., and Kirchner, J. G., Ibid., .24, 1480 (1952). (18) Kirchner, J. G., and Miller, J. M., Ind. Eng. Chem., 44, 318 (1952). (19) Miller, J. M., and Kirchner, J. G., Atnal. Chem., 25, 1107 (1953).' (20) Braddock, et al., Ibid., 25, 301 (1953).