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J. Soc. Cosmet. Chem., 42, 97-104 (March/April 1991) Gas chromatographic determination of 1,4-dioxane at the parts-per-million level in consumer shampoo products MARK P. ITALIA and MATHEWS A. NUNES, Johnson & Johnson Consumer Products Company, Grandview Road, Skillman, NJ 08558. Received November 16, 199•. Synopsis A packed-column gas chromatographic method for the determination of 1,4-dioxane in shampoo products is presented. The sample shampoo is diluted with water containing isobutanol as the internal standard and injected directly into a gas chromatograph containing a 12-foot X •/,-in stainless steel column packed with OV-1 as the stationary phase. The reproducibility of the method is better than 7% relative standard deviation, with 1,4-dioxane recoveries between 94 and 105%, and is linear over the range of 1 ppm to 250 ppm. The entire analysis can be performed in 15 minutes, allowing for fast sample turnaround. The ruggedness of the method has been demonstrated by the analysis of 13 shampoos, 12 containing ethoxylated surfactants and 1 containing no ethoxylates. All 12 products containing ethoxylated surfactants tested positive for 1,4-dioxane, with the range of 1,4-dioxane found being from 6 ppm to 144 ppm. INTRODUCTION Within the shampoo manufacturing sector of the cosmetics industry there is concern about the level of residual 1,4-dioxane present in final shampoo products. The 1,4- dioxane is introduced into the product via the use of ethoxylated fatty alcohol sulfates as cleansing agents. During the process of alcohol ethoxylation, ethylene oxide can dimerize to form 1,4-dioxane, which is subsequently carried through the shampoo manufacturing process. This compound has been shown to be carcinogenic in animals (1,2) and is listed as a carcinogen with NIOSH (3). Concern over the health risks, along with the probability that the ethoxylated surfactants in use contain a fair amount of residual 1,4-dioxane, has lead many cosmetic and toiletry companies to examine the levels of dioxane in both their raw materials and their finished products. Although many producers have begun vacuum stripping procedures in their manufacture of the fatty alcohol sulfates, there can still be high levels of 1,4-dioxane remaining in the materials that will be inadvertently added into finished product. Mark P. Italia's current address is Knoll Pharmaceuticals, Inc., 30 North Jefferson Road, Whippany, NJ 07981. 97