LC-ESI-MS study of the photo-polymerization products of triclosan

The safety of triclosan in the daily-used chemical products has evoked a great deal concern in the academic community due to the possible formation of dioxin in the photo-induced transformation. The photo-polymerization (PPM) of triclosan under UV irradiation and effects of light sources were investigated by using LC-ESI-MS and HPLC. By analyzing the ion chromatogram for different m/z at negative ion mode, three kinds of products (total seven PPM products) with molecular ion 505, 540 and 794 respectively were identified. The numbers of their isomers respectively were 2, 3 and 2. These compounds were formed by removal of HC1 among triclosan molecules or loss of chloride anions. 2, 8-dichlorodibenzo-p-dioxin transformed by ring-closure of triclosan was also detected in the photolysed products. The light source effects on the formation of PPM products were also investigated by utilizing the HPLC analysis. It was found that the PPM reaction was strongly affected by the light source, and the UVB was much more effective than the UVA.