690 .JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS ..... I • i I ] [ '• I ' ]•l• [ I I • I I ' .... Figure 4. Comparison of extraction methods Comparison Between the Base-Acid Extraction and the Acetonitrile- Hexane Method Figure 4 shows the GIJC recording of a co.mplex mixture after iso- lation by the two methods. While there is little interference from ex- traneous materials after acetonitrile-hexane, there is none after the base- acid extraction. The superiority of the base-acid extraction was ob- served with several formulations. The base-acid extraction method was selected for use because of its freedom from extraneous peaks. The ace- Ionitrile-hexane method is presented for its simplicity and may be used when interferences are known to 1)e absent. Recovery o[ Added Hexachlorophene Salnples of four marketed products were assayed for hexachlorophene. To aliquots of these an amount of hexachlorophene roughly equal to the amount present was added and the materials were then reassayed (Table II). Recoveries were essentially quantitative, the lowest being 95.5%. IIexachlorophene was added to three products not already containing this substance: talc, white ointment (U.S.P., a hydrocarbon beeswax corn-

DETERMINATION OF HEXACHLOROPHENE 691 Table II Recovery after Addition to Marketed Products (Already Containing Hexachlorophene) Hexachlorophene, mg Product Theoretical" Found Recovery, % Face powder 10.36 10.50 101.4 Lotion 12.87 12.65 98.3 Liquid makeup 14.27 13.63 95.5 Cream makeup 17.50 17.95, 17.05 100.0 Amount of hexachlorophene found by assay plus amount added. Table III Hexachlorophene Recovery from Laboratory Formulations Hexachlorophene, % (w/w) Standard Product Added Found Recovery, % Error, % Talc 0.5 0. 497 0. 476 0. 495 97.8 1.9 White Ointment, U.S.P. 0.1 0.101 0.097 0.101 99.3 2.1 Lotion" 0.2 0.189 0.194 0.184 94.9 2.2 a Composition: Polyethyleneglycol 400, 10% PEG 400 monostearate, 1% propylene glycol, 10% methyl par,ben, 0.2% lanolin isopropyl ester, 2% tocopherols, 0.1% antoxi- dant 221 BHA, 0.1% veegum, 0.2% and water, sufficient to make 100%. position), and a lotion whose coinposition is given in Table III. Assays were carried out in triplicate. Recoveries ranged from 94.9% for the lo- tion and 99.3% for the white ointment. These recoveries compare quite well with those reported by the Methods of Analysis Subcommittee (1). In the final method decided on, average recoveries of 94.8% to 100% were obtained. ADDENDUM Silylation of Dichlorophene tinder the same conditions dichlorophene may also be silylated and chromatographed. In Fig. 5 is the chromatographic record obtained when 2 v1 of a solution containing 5.6 vg of dichlorophene, 3.8 vg of DCHP, and 11.8 t'g of hexachlorophene is chromatographed as described above. Good separation is obtained between the two bisphenols and the internal standard.