ABSTRACT
BACKGROUND: 1,4-Dioxane (1,4-D) is a by-product of the synthesis of surfactants, typically found in some cosmetics products such as shampoo, toothpaste, and soap. The presence of 1,4-D in cosmetics products is limited to certain amount since 1,4-D is classified as a probable human carcinogen. OBJECTIVE: This present study was intended to validate static headspace gas chromatography-mass spectrometry (HS GC-MS) for the determination of 1,4-D in cosmetics products. METHODS: The condition of headspace and GC-MS was optimized to get the best condition for analysis of 1,4-D using 1,4-Dioxane-d8 (1,4-D-d8) as internal standard (IS). The developed method was validated by evaluating the key performance characteristics, including specificity, linearity, limit of detection (LoD), limit of quantification (LoQ), accuracy, and precision. RESULTS: The results showed that HS GC-MS was specific since the peaks of the selected ion monitoring (SIM) mode could be separated and confirmed at m/z 88 and m/z 96 for 1,4-D and 1,4-D-d8, respectively. The method was linear over the concentration range of 0.1287-1.2875 µg/mL, with R2 > 0.999 and RSD residuals < 2.0. A collaborative study were conducted on this method, with ten participating laboratories from four countries. The outcome of this study was found to be accurate and precise, as evidenced by the excellent recoveries ranged from 94.6-102.1% and with good reproducibility with RSD values ranged from 0.2-1.1%. The collaborative studies exhibited that all data reported by ten participating laboratories in four countries were inliers without any extreme values observed either in mean or RSD values. CONCLUSION: This HS GC-MS is found to be fit and suitable for the determination of trace level of 1,4-D in cosmetics products. HIGHLIGHTS: HS GC-MS method could be proposed as a standard method for quantitative analysis of 1,4-D in cosmetics products since the collaborative studies indicated that the developed method meet the requirement in "Guidelines for Collaborative Study Procedures to Validate Characteristics of a Method of Analysis".
