Clermont Université, Université Blaise Pascal, Laboratoire de Photochimie Moléculaire et Macromoléculaire, UMR CNRS 6505, Clermont Ferrand, France.
Photochem Photobiol. 2010 Mar-Apr;86(2):247-54. doi: 10.1111/j.1751-1097.2009.00654.x. Epub 2009 Nov 23.
Photodegradation in aqueous solutions is an important pathway for many agrochemicals such as pesticides. In the present work, the photochemical transformation of cyanophos (CYA) was investigated in aqueous solutions using UV light within the 254-313 nm range as well as solar light. The study was performed in order to have a deep insight into the mechanistic pathways for the photochemical disappearance of CYA. Upon UV irradiation of an aerated solution of CYA, the degradation quantum yield was found equal to 1.8 x 10(-2). It is independent of the excitation wavelength but varies with oxygen concentration. It increased by a factor of 2 from oxygen-saturated to oxygen-free solution. Photosensitized experiments were performed using acrylamide and hydroquinone as energy acceptor and energy donor substrates, respectively. They show that both singlet and triplet excited states were involved in the photochemical behavior of CYA. The laser flash photolysis experiments clearly showed the involvement of the triplet excited state which was efficiently quenched by molecular oxygen and acrylamide with the rate constants 1.97 x 10(9) and 2.71 x 10(9) mol(-1) L s(-1), respectively. The photoproducts structures were proposed according to the mass spectral data using the LC/MS technique. The analytical study shows that various processes such as hydrolysis, homolytic bond dissociations and Photo-Fries process occur.
在水溶液中的光降解是许多农用化学品（如杀虫剂）的重要途径。在本工作中，使用 254-313nm 范围内的紫外光以及太阳光研究了水中氰戊菊酯（CYA）的光化学转化。这项研究的目的是深入了解 CYA 光化学消失的机制途径。在有氧的 CYA 溶液中进行紫外线照射时，发现降解量子产率等于 1.8×10(-2)。它不依赖于激发波长，但随氧气浓度而变化。从饱和氧到无氧溶液，它增加了 2 倍。使用丙烯酰胺和对苯二酚分别作为能量受体和能量供体底物进行光敏化实验。结果表明，单重态和三重态激发态都参与了 CYA 的光化学反应。激光闪光光解实验清楚地表明，三重态激发态参与了反应，它被分子氧和丙烯酰胺有效地猝灭，速率常数分别为 1.97×10(9)和 2.71×10(9)mol(-1)L s(-1)。根据使用 LC/MS 技术的质谱数据提出了光产物的结构。分析研究表明，发生了各种过程，如水解、均裂键离解和 Photo-Fries 过程。
