Occurrence of Benzotriazole-Based UV Absorbers in Japanese Household Dust

Benzotriazole-based ultraviolet absorbers (BUVs) are widely used in polymers due to their high thermal and photo stability. However, their environmental persistence and bioaccumulation potential have raised concerns, and some have become subject to regulation. BUVs have been detected in water, air, road dust, biota, and indoor products such as plastics and paints. They have also been frequently found in household dust (HD), which accumulates semi-volatile organic compounds; however, no studies to date have investigated the presence of BUVs in Japanese HD. This study established an LC–MS/MS method with atmospheric pressure chemical ionization (APCI) to quantify eight BUVs in HD and evaluate their occurrence in Japanese residences. Here, eight BUVs were selected for analysis, including UV-320—classified as a Class I specified chemical substance under Japan’s Chemical Substances Control Law—and UV-328, newly listed in 2024. Sample preparation was optimized by evaluating six solid-phase extraction methods, among which basic alumina-based cartridges demonstrated selective BUV retention. High recoveries ranging from 86.9 to 100% were achieved using a back-flush elution approach. Using the developed method, HD samples collected in 2023 and 2024 were analyzed. Six compounds, excluding UV-320 and UV-PS, were detected in 100% of the samples. Although the maximum and minimum concentrations varied considerably between the two years, the median values and detection frequencies showed generally consistent trends. These findings reveal the contamination status of BUVs in Japanese HD and demonstrate that the developed APCI–LC–MS/MS method is a reliable approach for indoor pollution monitoring.