JOURNAL OF COSMETIC SCIENCE 496 extracts without further treatment. To confi rm the identity of analyte peaks, chromato- graphic peak identifi cations were confi rmed by retention time, peak width, and the UV spectrum of the chromatographic peak. RECOVERY STUDIES A tertiary solvent mixture was chosen that contained mutually miscible solvents: 1/3 (v/v) hexane, 1/3 (v/v) isopropanol, and 1/3 (v/v) ethyl acetate. This solvent mixture gave good recoveries of retinoids from a wide range of sample matrices. The solvent mixture was also compatible with direct injection onto the column without further sample ma- nipulation, which helped minimize the decomposition of the extracted retinoids. Table I shows results obtained for four different sample matrices spiked with four differ- ent levels of retinoic acid, retinol, and retinyl palmitate. Recoveries were generally 95% or greater. Since additional studies showed that increasing the volume of extractant did not lead to better recoveries, a single liquid/solid extraction using 10 ml of extractant was chosen for simplicity and rapidity. COSMETIC SKIN CARE PRODUCTS SURVEYED The 29 consumer cosmetics surveyed in this study included anti-wrinkle, anti-aging, skin renewal, line removal, skin-whitening, skin-moisturizing, and skin-cleansing prod- ucts, and were in the form of creams, lotions, complexes, and serums (see Table II for more information on each cosmetic product analyzed). Many of the products highlighted the presence of vitamin A and/or other vitamins in the formulation (e.g., “vitamin en- riched,” “a natural vitamin A wrinkle cream,” “retinol formula,” “a retinol facial treat- ment with multi-vitamins,” “refi ning night cream with 0.5% pure retinol,” “vitamin A cream extra strength,” “max retinol vitamin A,” and “double retinol wrinkle treatment”). Seventeen (59%) of the products included retinol, either in the product name or in the list of ingredients, four included retinyl palmitate, and six included both. One product found to contain retinoid did not indicate the presence of either retinol or retinyl palmi- tate in the list of ingredients. Twenty-fi ve (86%) of the products were labeled to contain anti-oxidants or stabilizers such as vitamin C, vitamin E, BHT, and di- or tetra-sodium EDTA to prevent oxidation or decomposition of the retinol or retinyl palmitate. In addition, 22 products (76%) were labeled to contain a sunscreen, recommended use with a sunscreen, or recommended night-time use only due to the possibility of increased photosensitivity. Finally, 18 prod- ucts (62%) provided product use warnings such as “for external use only,” “avoid contact with the eyes or mucous membranes,” “discontinue use if persistent irritation occurs,” or “keep out the reach of children.” SURVEY RESULTS The results of the analysis are given in Table III. Eighteen products (62%) were found to contain retinol. Six (21%) were found to contain retinyl palmitate, and fi ve (17%) were found to contain both retinol and retinyl palmitate. No products were found to contain

DETERMINATION OF RETINOIDS IN COSMETICS 497 Table II Sample Descriptions Product type Labeled ingredient Anti-oxidant or stabilizer Sunscreen included or recommended Product use warning Anti-wrinkle facial serum RP Isostearic acid Vitamin E EDTA Not listed Not listed Wrinkle-corrector cream RL BHT Apply morning or evening Not listed Line defense complex RL Not listed Use SPF 15 daily Yes Liquid makeup Not listed Not listed SPF 20 Yes Anti-wrinkle cream RP Vitamin E Not listed Not listed Anti-cellulite treatment cream RL BHT EDTA Not listed Yes Anti-wrinkle cream RL EDTA Vitamin E BHT SPF 15 Yes Nightly renewal cream RL Vitamin C BHT EDTA Night-time use Yes Line eliminator RL Vitamins C and E BHT EDTA Night-time use only Yes Renew body serum RP EDTA Not listed Not listed Refi ning night cream RL BHT EDTA Use sunscreen Yes Wrinkle corrector RL Not listed Not listed Not listed Day cream RP BHT Vitamin E EDTA SPF 20 Yes Anti-wrinkle treatment cream RL Vitamin E EDTA BHT Use sunscreen Not listed Anti-wrinkle night complex RL Vitamin E EDTA Use sunscreen Yes Skin-refi ning lotion RL EDTA Not listed Yes Skin-whitening serum RL EDTA Vitamins E and C BHT Use nightly Yes Anti-wrinkle cream RL Vitamin C BHT EDTA Use nightly Not listed Anti-wrinkle cream RL/RP Vitamin E EDTA SPF 20 Yes Wrinkle treatment RL EDTA BHT Vitamins C and E Use nightly Not listed Anti-age complex RL Vitamin E BHT EDTA Nightly use Yes Smoothing serum RL Not listed Nightly use Yes Moisturizer RL/RP Vitamins E and C EDTA Nightly use Yes Clean complex RL/RP EDTA Use sunscreen Yes (Continued)