Photodegradation of perfluorooctanoic acid by 185 nm vacuum ultraviolet light

The photodegradation of persistent and bioaccumulative perftuorooctanoic acid （PFOA） in water by 185 nm vacuum ultraviolet （VUV） light was examined to develop an effective technology to deal with PFOA pollution. PFOA degraded very slowly under irradiation of 254 nm UV light. However, 61.7% of initial PFOA was degraded by 185 nm VUV light within 2 h, and defluorination ratio reached 17.1%. Pseudo first-order-kinetics well simulated its degradation and defluorination. Besides, fluoride ion formed in water, 4 shorter-chain perfluorinated carboxylic acids （PFCAs）, that is, perfluoroheptanoic acid, perfluorohexanoic acid, perfluoropentanoic acid, and perfluorobutanoic acid. These were identified as intermediates by LC-MS measurement. These PFCAs consecutively formed and further degraded with irradiation time. According to the mass balance calculation, no other byproducts were formed. It was proposed that PFCAs initially are decarboxylated by 185 nm light, and the radical thus formed reacts with water to form shorter-chain PFCA with one less CF2 unit.

硝苯吡啶水凝胶型骨架片剂的研制

根据水凝胶骨架释放机制,研制了硝苯吡啶溶蚀型骨架片剂A。其体外溶出行为符合一级动力学过程。体外环境如介质、桨速不影响其溶出行为。片剂A的体内血浓用气相色谱法测定,其体内配置状态以二室模型描述较为适宜,经计算机模型嵌合程序迭代处理求得动力学参数。生物等效性研究表明:片A与国外长效片B无显著差异,而与市售普通片C有显著差异。A相对于B和C的生物利用度分别为97.66%和281.80%。稳定性试验表明片剂A对光不稳定,温度、湿度对其基本无影响。薄膜包衣延缓了药物的光解。