j. Soc. Cosmet. Chem., 45, 35-42 (January/February 1994) Assay of triclosan in deodorant sticks and soaps by supercritical fluid extraction and HPLC SANTO SCALIA, MARIO GUARNERI, and ENEA MENEGATTI, Istituto di Chimica Farmaceutica, Universit• di Catania, Via Andrea Doria 6, 95125 Catania (S.S.), and Dipartimento di Scienze Farmaceutiche, Universit• di Ferrara, Via Fossato di Mortara 17, 44100 Ferrara (M.G., E.M.), Italy. Received September 24, 1993. Synopsis A rapid and efficient procedure was developed for the isolation of the bacteriostat triclosan from deodorant stick and soap matrices using supercritical fluid extraction (SFE). Quantitative recovery for triclosan was obtained with two sequential 7.5-min extraction steps using supercritical carbon dioxide at a density of 0.85 g/ml and at a temperature of 40øC for stick preparations or 50øC for soap products. The SFE method was compared with conventional liquid extraction and was found to achieve improved recovery and spec- ificity within a shorter time span. The automated extraction by SFE minimized sample handling, affording enhanced precision. Moreover, SFE reduced the use of hazardous solvents. Triclosan was assayed in com- mercial deodorant products by high-performance liquid chromatography after extraction with supercritical carbon dioxide according to the described procedure. INTRODUCTION The majority of marketed deodorants incorporate an antimicrobial agent (1-3) to inhibit the development of the microorganisms responsible for sweat degradation and malodor generation (4,5). Triclosan (2,4,4'-trichloro-2'-hydroxydiphenyl ether) is the most widely used bacteriostat in deodorant sticks, and it is commonly contained in deodorant soaps (1,2,6). It is included in the list of the antimicrobial agents authorized by the European Economic Community (EEC) directive on cosmetics (7), and it is permitted for use at a maximum concentration of 0.3% (w/w). Hence, the assay of this compound in commercial cosmetics is important for quality control of finished products and for checking their conformance to the EEC legislation (7). Published procedures for the quantitative determination of triclosan in deodorants and other cosmetic preparations are based on spectrophotometry (8), thin-layer chromatog- raphy (9), and high-performanc% liquid chromatography (HPLC) (6,10). The latter technique is the method of choice since it achieves improved specificity and precision. Prior to HPLC analysis of deodorant products, a sample preparation step is necessary to remove the formulation components that can interfere with the analyte determination 35

36 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS and/or cause deterioration of the chromatographic column (6,11). Moreover, solid and semisolid samples such as deodorant sticks and soaps must first be put into solution before injection into the chromatograph. These processes require several sample manip- ulations (e.g., liquid extraction, mixing, sonication, heating, centrifugation, and var- ious sample transfers) that represent a source of possible errors (6,10,11). In addition, the organic solvents used must eventually be disposed of. Supercritical fluid extraction (SFE) has recently become an attractive alternative to traditional liquid extraction methods for the isolation of organic analytes from solid and semisolid matrices (12). SFE uses fluids above their critical pressure and temperature as the extraction medium. Supercritical fluids have densities and solvating powers ap- proaching those of liquids, but they exhibit higher solute diffusivities and lower vis- cosities that lead to more rapid and efficient extractions (12). Moreover, since the solvent strength of a supercritical fluid is directly related to its density (13), it can be modified by simply changing the extraction pressure and/or the temperature (14). Finally, the most commonly used supercritical fluid, carbon dioxide, has the advantage of being nontoxic, non flammable, relatively inexpensive, and easily removed from the extract, as it is gaseous at ambient conditions. This study reports on the development of an SFE procedure for the rapid and efficient isolation of triclosan from deodorant sticks and soaps prior to assay by HPLC. The application of the method to the quantitative determination of triclosan in commercial products is also demonstrated. EXPERIMENTAL MATERIALS Instrument-grade liquid carbon dioxide supplied in cylinders with a dip tube was obtained from SIAD (Bergamo, Italy). Methanol, acetonitrile, tetrahydrofuran, and water were all HPLC-grade as supplied by J. T. Baker (Phillipsburg, NJ). Triclosan and triclocarban (3,4,4'-trichlorocarbanilide) were a gift from Formenti (Milan, Italy). The standards were checked for the absence of other HPLC peaks prior to use. Commercial cosmetics were from retail stores. CHROMATOGRAPHY The HPLC apparatus consisted of a modular chromatographic system (model 880-PU pump and model 875-UV variable-wavelength UV/VIS detector Jasco, Tokyo, Japan) linked to an injection valve with a 20-}xl sample loop (model 7125 Rheodyne, Cotati, CA) and a chromatographic data processor (Chromatopac C-R3A Shimadzu, Kyoto, Japan). The detector was set at 280 nm and 0.32 absorbance units full scale. A high- speed scanning detector (Chrom-A-Scope Barspec Ltd., Rehovot, Israel) was used to obtain the absorbance spectrum of the column effluent over the wavelength range of 220-340 nm. Separations were performed on a LiChrospher CH-8 column (5-}xm particle diameter, 250 X 4.0 mm i.d. Merck, Darmstadt, Germany) fitted with a guard column particle diameter, 4 X 4 mm i.d. Merck) and eluted under isocratic conditions with