Department of Chemistry, University of New Orleans , 2000 Lakeshore Drive, New Orleans, Louisiana 70148, United States.
Environ Sci Technol. 2017 Oct 17;51(20):11858-11866. doi: 10.1021/acs.est.7b01991. Epub 2017 Sep 27.
Aldehyde and ketone photoproducts were observed in the aqueous phase under oil exposed to simulated sunlight by using 2,4-dinitrophenylhydrazine (DNPH) derivatization and electrospray ionization-tandem mass spectrometry (ESI-MS/MS). Oil samples were spread over seawater in a jacketed beaker held at 27.0 °C and exposed to simulated sunlight. The aqueous phase was collected after irradiation and derivatized with DNPH, which selectively reacts with aldehydes and ketones. The derivatized hydrazones (aldehyde- and ketone-DNPH derivatives) were washed and enriched with a solid-phase extraction cartridge prior to analysis by ESI-MS/MS in negative ion mode. Over 80 aldehyde and ketone photoproducts were observed from scan range 200-1000 atomic mass units (amu) in the aqueous phase after irradiation but were absent in dark controls. Based on the MS/MS fragmentation of the aldehyde- and ketone-DNPH derivatives, most of the aldehyde and ketone photoproduct mass spectra observed from the aqueous phase were determined to be consistent with dicarbonyls, hydroxycarbonyls, and oxo-carboxylic acids. The formation of the photoproducts can be attributed to photoinduced oxidation of oil. The approach in this study allows the easy identification of molar mass and other structural features of aldehyde and ketone photoproducts without interference from the many tens of thousands of parent compounds in the oil. These results will provide insight into the impact of photochemistry on the fate of oil in environmental systems and will have implications for oil-spill response decisions.
采用 2,4-二硝基苯肼（DNPH）衍生化和电喷雾串联质谱（ESI-MS/MS），在油相中观察到暴露于模拟阳光下的油中醛酮光产物。将油样铺展在夹套烧杯中的海水中，在 27.0°C 下保持，并暴露于模拟阳光下。辐照后收集水相并用 DNPH 衍生化，DNPH 选择性地与醛酮反应。衍生化的腙（醛酮-DNPH 衍生物）用固相萃取小柱洗涤和富集，然后在负离子模式下通过 ESI-MS/MS 进行分析。辐照后，在水相中从扫描范围 200-1000 原子质量单位（amu）观察到 80 多种醛酮光产物，但在暗对照中不存在。根据醛酮-DNPH 衍生物的 MS/MS 碎片，从水相中观察到的大多数醛酮光产物的质谱被确定为与二羰基、羟基羰基和氧代羧酸一致。光产物的形成可归因于油的光诱导氧化。本研究方法允许在不干扰油中数万种母体化合物的情况下，轻松识别醛酮光产物的摩尔质量和其他结构特征。这些结果将深入了解光化学对环境系统中石油命运的影响，并将对溢油应急决策产生影响。
