Ozone and UV photolysis can be effective for the treatment of pharmaceuticals in wastewater, however, these processes can result in the formation of potentially toxic transformation products (TPs). This study investigates the structural elucidation of the TPs formed during ozone and UV treatments of diclofenac (DCF), a ubiquitous pharmaceutical. Using liquid chromatography – electrospray ionisation - mass spectrometer (LC-ESI-MS) and a Waters Xevo™ Quadrupole Time-of-Flight (Qtof) mass spectrometer, the chemical structures of DCF TPs were identified, including the fragmentation ion patterns and exact mass of the detected molecular ions. TPs formed during ozonation showed an addition of one or more hydroxyl groups to the DCF molecule including changes to the double bond equivalent for some products. The other identified DCF ozonation products were formed by removal of the (-CH₂COOH) group in two steps and resulted in the formation of a diverse range of TPs. By contrast, UV photolysis formed DCF TPs via removal of its chlorine atoms and ring closure followed by dimerization. In comparison, all ozonation TPs retained the two chlorine atoms of DCF whereas UV TPs did not possess any chlorine atom except for one compound that retained one chlorine atom. Possible reaction pathways for the identified DCF TPs are also proposed.

臭氧和紫外线光解可有效处理废水中的药物，但是，这些过程可能会导致潜在有毒转化产物 (TP) 的形成。本研究调查了双氯芬酸 (DCF)（一种普遍存在的药物）在臭氧和紫外线处理期间形成的 TP 的结构解析。使用液相色谱 - 电喷雾电离 - 质谱仪 (LC-ESI-MS) 和 Waters Xevo™ 四极杆飞行时间 (Qtof) 质谱仪，鉴定了 DCF TP 的化学结构，包括碎片离子模式和精确质量检测到的分子离子。臭氧化过程中形成的 TP 表明 DCF 分子中添加了一个或多个羟基，包括某些产品的双键当量发生变化。₂ COOH) 基团分两步，导致形成各种不同的 TP。相比之下，紫外线光解通过去除其氯原子和闭环然后二聚形成 DCF TP。相比之下，所有臭氧化 TP 都保留了 DCF 的两个氯原子，而 UV TP 没有任何氯原子，除了一种化合物保留了一个氯原子。还提出了已鉴定的 DCF TP 的可能反应途径。