Photochemical fate of the vasodilator drug pentoxifylline in surface waters

This study is the first to comprehensively investigate the photochemical fate of pentoxifylline in natural water systems. Among all attenuation processes, indirect sunlight photolysis is very likely the primary process for pentoxifylline degradation. The combination of dissolved organic matter (represented by fulvic acid), NO₃⁻ and HCO₃⁻ closely simulated the photolysis rate in real surface water (Jingmei River, Taipei) (t_1/2 = 34.7 ± 2.2 h), indicating that these three parameters are the most important determinants of the photolysis fate of pentoxifylline. The results also showed that HCO₃⁻ contributes to photodegradation of pentoxifylline in the NO₃⁻ system due to the participation of ·CO₃⁻. Although pentoxifylline was degraded, total organic carbon remained constant during the photolytic process, indicating that byproducts were generated in the solution. Five byproducts that have not been previously reported are proposed for the first time in this study. Among all of the byproducts, two byproducts (P4 (M.W. = 250) and P5 (M.W. = 227)) were only detected in the presence of NO₃⁻ and HCO₃⁻, implying that ·CO₃⁻ possibly caused different photolytic pathways of pentoxifylline.