J. Soc. Cosmetic Chemists 17 3-8 (1966) ¸ 1966 Society of Cosmetic Chemists of Great Britain Determination of chlorinated phenols in powdered deodorants S. LEE and N. A. PUTTNAM* Synopsis--A rapid UV spectroscopic method is described for the determination of hexa- chlorophene in powdered personal deodorants. The method is based on the absorbance at 33.8 Kcm -x (296 m/x) of an acidic methanol extract of the product. The standard deviation is q- 0.005% at the 0.5% hexachlorophene level. The presence of a chloroxylenol is indicated by an increase in the absorbance at 35.8 Kcm -x (279 m/x) and can be determined simultaneously. If the identity of the chloroxylenol is unknown, the use of an average lEl value at 35.8 I(cm -x only introduces serious error if the chloroxylenol should happen to be 4-chloro-2:5-dimethyl or 6-chloro-3:4-dimethyl phenol. INTRODUCTION Chlorinated phenols are frequently incorporated into personal deodorants as bacteriocides, the most commonly used being hexachloro- phene [2:2Lmethylene-bis-(3:4:6-trichlorophenol)]. However, recent for- mulations have employed a chloroxylenol as an antiseptic agent in con- junction with hexachlorophene. Such compounds, in common with other phenols, show absorption maxima in the wavelength range 270 to 300 m•, the exact frequency being dependent upon the type and position of sub- stituents within the aromatic ring. Under alkaline conditions the absorp- tion maxima are shifted approximately 20 m• towards longer wavelengths, due to the formation of a phenate ion. This shift is often used in the determination of phenols to reduce interferences from other components of the system. However, in "partially hindered phenols," such as hexa- chlorophene, ionisation is only complete in the presence of relatively high concentrations of alkali (1). Absorptions due to both the phenol and the phenate ion are detected in the presence of insufficient alkali. Clements and Newburger (2) have described a UV spectroscopic method for the determination of hexachlorophene in soaps and cosmetic prepara- *Research and Development Department, Colgate-Palmolive Limited, Manchester, 5.

JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS tions. In their procedure, the hexachlorophene was extracted from the product with alkali and then isolated, by acidifying this extract, prior to the spectroscopic determination. A similar determination has been reported by Elvidge and Peutrell (3), which was based on the "difference" absorption at 312 mt• of the sample in a solution buffered at pH 8.0 and in a solution buffered at pH 1.4. Such procedures suffer from the disadvantage that deodorants usually contain aluminium compounds as antiperspirants, which, on treatment with alkali, produce a gelatinous precipitate of aluminium hydroxide with is difficult to remove. In the present communication, which describes a rapid method for the determina- tion of hexachlorophene in powdered personal deodorants, this difficulty is overcome by the use of acidic methanol. The method is based on the absorbance at 33.8 Kcm -• (296 mr,) of an acidic methanol extract of the product. The presence of a chloroxylenol is readily detected at 35.8 Kcm -• (279 ms) and is determined simultaneously. EXPERIMENTAL The spectra were determined on a Unicam SP 700 recording UV/near IR spectrophotometer in 10 mm silica cells. The reference data for hexachlorophene and the chlorinated xylenols was obtained by weighing approx. 100 mg of the phenol into a 50 ml graduated flask and diluting to volume with N/10 methanolic HC1 (pre- pared by adding 100 ml of N/1 hydrochloric acid to a litre graduated flask and diluting to volume with Spectrosol grade methanol). 1 ml of this solution was then pipefred into a 100 ml graduated flask and diluted to volume with solvent. The spectrum of this solution was then recorded against a solvent blank over the wavelength range 41 Kcm -• (224 m?) to 30 Kcm -• (333 ms). A tangent base-line to the absorptions was then .drawn and the E• values, i.e. the absorbance for a 1% solution in a 10 mm •cell, at 33.8 Kcm -• (296 ms) and 35.8 Kcm -• (279 ms) calculated. For the analysis of a powdered deodorant, 0.5 g of the sample was weighed into a 50 ml centrifuge tube and 25 ml of N/10 methanolic HC1 .added. The contents of the tube were agitated for 3 min with a glass rod and then centrifuged at 3000 rpm for 2 min. The upper layer was decanted into a 100 ml graduated flask and the residue re-extracted with a further 2 x 25 ml portions of solvent. The methanolic extracts were combined in the graduated flask and made up to volume with solvent. The spectrum of this solution was then recorded, as described above, and the E• values at 33.8 Kcm -x and 35.8 Kcm -• similarly calculated.