去氢孕酮在水中的光化学转化过程及降解产物鉴定

何智俐; 高爽; 李文彦; 李永涛; 杨行健; 孙岩

doi:10.7671/j.issn.1001-411X.202204002

去氢孕酮在水中的光化学转化过程及降解产物鉴定

Phototransformation and photoproduct identification of dydrogesterone in water

摘要

摘要:
目的探究典型合成孕激素去氢孕酮(Dydrogesterone，DYD)在模拟太阳光下的光化学转化过程及转化路径。
方法利用光化学反应器，测试模拟太阳光下DYD的光解动力学过程，探究不同pH(5、7和9)、温度(15、25和35 ℃)和天然有机质(Natural organic matter，NOM)质量浓度(0、5和20 mg·L⁻¹)对DYD光解速率的影响，利用超高效液相色谱–飞行时间质谱(UHPLC-QTOF-MS)鉴定DYD光解后产生的潜在产物，并推测潜在的反应路径。
结果光照条件下DYD浓度逐渐降低，说明DYD发生了光降解过程。DYD的光解速率受溶液初始pH影响不明显，一阶光解动力学速率常数(k)为0.015~0.019 h⁻¹；DYD的光解速率在高温和低浓度NOM条件下有所提升(k从0.019 h⁻¹分别升至0.027和0.028 h⁻¹)，但在高浓度NOM条件下被抑制。UHPLC-QTOF-MS分析表明，DYD在光解过程中共生成19种产物，主要为羟基化、加氢、缩聚、光异构化以及开环后的反应产物。
结论 DYD在地表水中会发生光降解作用，温度和NOM是影响其光解的重要因素；光解后形成的19种产物仍保留了DYD的分子骨架，因此可能仍具有潜在的内分泌干扰效应。

Abstract:
Objective To explore the phototransformation of a synthetic progestin, dydrogesterone (DYD), under simulated sunlight, and identify its potential transformation pathways.
Method Photoreactor was used to test the phototransformation process of DYD under simulated sunlight. Experiments were also conducted to explore different pH (5, 7, and 9), temperature (15, 25, and 35 ℃), and natural organic matter (NOM) concentration (0, 5, and 20 mg·L⁻¹) on DYD phototransformation rate. Ultra-high performance liquid chromatography-time of flight mass spectrometer (UHPLC-QTOF-MS) was used to identify the potential photoproducts of DYD, and the potential transformation pathways were speculated.
Result The concentration of DYD decreased over time under simulated sunlight, indicating that phototransformation occurred in the system. DYD transformation rate was not obviously affected by the initial solution pH, and the first-order phototransformation kinetic rate constant (k) was 0.015−0.019 h⁻¹. DYD transformation rate was facilitated by high temperature and low concentration of NOM (k increased from 0.019 h⁻¹ to 0.027 and 0.028 h⁻¹, respectively), but was inhibited by high concentration of NOM. UHPLC-QTOF-MS analysis showed that 19 photoproducts were generated during transformation, via hydroxylation, hydrogenation, polycondensation, and photoisomerization with subsequent ring-opening reactions.
Conclusion Phototransformation will occur for DYD in surface water, and temperature and NOM play important roles in DYD phototransformation. A total of 19 photoproducts detected in this study remain the basic molecular skeleton of DYD, indicating that these products would exhibit potential endocrine disruption to aquatic systems.

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