Although it is known that the solar irradiation of chromophoric dissolved organic matter (CDOM) solutions generates H₂O₂, whether or not organic hydroperoxides (ROOHs) are photochemically formed remains unclear. This study employs high-performance liquid chromatography with the postcolumn enzymatic derivatization method to examine whether ROOHs can be formed in CDOM solutions under simulated solar irradiation. Methylhydroperoxide (MHP) is the only identified ROOH under our experimental conditions, and the quantum yields of MHP (Φ_MHP) vary from (1.09 ± 0.09) × 10^–6 to (4.95 ± 0.11) × 10^–6 in the tested CDOM solutions, including four reference natural organic matters and two effluent organic matters. The quantum yields of H₂O₂ (Φ_H2O2) are simultaneously measured, and the ratios of Φ_H2O2 to Φ_MHP range from 147 to 676. The formation of MHP is highly related to the presence of superoxide radical ions (O₂^•–) and methyl radicals (CH₃^•); therefore, a photoformation mechanism of MHP has been proposed. The photochemically generated CH₃^• reacts with O₂ to yield CH₃OO^•. Subsequently, CH₃OO^• is reduced to MHP by O₂^•–. Our results also suggest that the yield of CH₃^• to MHP under air-saturated conditions is 52% and increases to 98% under oxygen-saturated conditions. The decays of MHP and H₂O₂ are very similar in terms of photodegradation, hydrolysis, Fenton, and photo-Fenton reactions. This study can be useful to understand the photochemical formation of organic peroxides in surface waters.

中文翻译：

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溶解有机物溶液中氢过氧化甲基的光化学形成

尽管已知发色溶解的有机物（CDOM）溶液在阳光下照射会产生H ₂ O ₂，但尚不清楚是否以光化学方式形成有机氢过氧化物（ROOH）。这项研究采用高效液相色谱和柱后酶衍生法研究在模拟太阳辐射下CDOM溶液中是否可以形成ROOH。Methylhydroperoxide（MHP）是我们的实验条件下的唯一识别ROOH，和MHP（Φ的量子产率_MHP）从（1.09±0.09）×10变化^-6至（4.95±0.11）×10 ^-6在经过测试的CDOM解决方案中，包括四种参考天然有机物和两种废水有机物。的量子产率ħ ₂ ö ₂（Φ _{ħ 2 ö 2}）被同时测量，和Φ的比率_{ħ 2 ö 2}至Φ _MHP从147至676范围内的MHP的形成高度相关超氧自由基的存在离子（O ₂ ^•–）和甲基（CH ₃ ^•）；因此，已经提出了MHP的光形成机理。光化学生成的CH ₃ ^•与O ₂反应生成CH ₃OO ^•。随后，CH ₃ OO ^•被O ₂ ^•–还原为MHP 。我们的结果还表明，在空气饱和条件下，CH ₃ ^•转化为MHP的产率为52％，在氧饱和条件下可提高至98％。就光降解，水解，芬顿和光芬顿反应而言，MHP和H ₂ O ₂的衰减非常相似。这项研究对于了解地表水中有机过氧化物的光化学形成可能是有用的。