The determination of 1,4-dioxane in cosmetic products by gas chromatography with tandem mass spectrometry.

1,4-dioxane is a potential human carcinogen and contaminant produced during the manufacturing process from specific cosmetic ingredients, such as certain detergents and emulsifiers. As such, 1,4-dioxane is not identified on product ingredient labels. To assess the concentration of 1,4-dioxane in cosmetic products, a gas chromatography-tandem mass spectrometry (GC-MS/MS) method using pulsed split injection and electron ionization was developed and validated. For liquid cosmetic products such as shampoo and lotion, test portions were extracted using fast ultrasound-assisted extraction (UAE) procedure without sample cleanup. For solid products (e.g. beauty bars), a C solid phase extraction (SPE) procedure was optimized to reduce potential interferences. The corresponding stable isotopically labeled analogue (1,4-dioxane-d) was selected as an internal standard to compensate for matrix effects and sample recovery. Method recovery experiments were performed in lotion, oil gel, hair detangler, bubble bath and beauty bar (solid) sample matrices with recoveries of 84-108% and relative standard deviations less than 5% at three spike concentrations. Method limits of detection (LOD) and quantification (LOQ) for 1,4-dioxane were determined at 0.2 μg/g and 0.5 μg/g, respectively. The method was successfully used to determine 1,4-dioxane in 82 leave-on and rinse-off cosmetic products marketed toward children including bath products, hair treatment, lotions, beauty bars, washes, shampoos, and other products. 1,4-dioxane was detected in 47 of the 82 products with an average concentration of 1.54 μg/g (range: 0.23-15.3 μg/g). The method can increase sample throughput and reduce matrix-induced interferences.