Determination of dioxane residue in cosmetics by isotope dilution-headspace gas chromatography-mass spectrometry

A comprehensive analytical method based on isotope dilution-headspace gas chromatography-mass spectrometry was developed for the determination of dioxane residue in the cosmetics. Cosmetic sample (2 g) was placed in a headspace vial. Then, 1 g sodium chloride, 1 mL d8-dioxane solution (20 mg/L) and 9 mL water were added. The vial was sealed and heated at 70 degrees C for 40 min. The qualitative and quantitative analyses were carried out for the analyte in selected ion monitoring (SIM) mode after the chromatographic separation on an HP-5MS column (30 m x 0.25 mm x 0.25 microm). The limit of quantification (LOQ) for dioxane was 2.5 mg/kg. The mean recoveries were 90.5% - 104.0% at the spiked levels of 2.5 - 50 mg/kg with the relative standard deviations in the range of 1.26% - 3.98%. The method is accurate, simple, rapid, and applicable for the inspection of dioxane residue in cosmetics.