Department of Green Chemistry, LUT University, Sammonkatu 12, FI-50130 Mikkeli, Finland.
Department of Chemistry and Biochemistry, 1175 North Horseshoe Drive, New Mexico State University, Las Cruces, NM, 88003, USA.
Sci Rep. 2019 Apr 3;9(1):5593. doi: 10.1038/s41598-019-41485-7.
The performance of a differential mobility spectrometer was characterized at ambient pressure and ten values of water vapor concentration, from 1.0 × 10 to 1.7 × 10 ppm using a homologous series of seven ketones from acetone to 2-dodecanone. Dispersion plots at 30 °C with separation fields from 35 to 123 Td exhibited increased alpha functions for the hydrated proton, protonated monomers, and proton bound dimers with increased moisture levels. Increases in the level of moisture were accompanied by decreased quantitative response with progressive suppression in the formation of the proton bound dimer first and then protonated monomer. Product ions for 2-octanone at 7 ppb were not observed above a moisture level of 4.0 × 10 ppm, establishing a limit for observation of analyte ion formation. The observation limit increased from 1.1 × 10 ppm for acetone to 5.7 × 10 ppm for 2-dodecanone. These findings demonstrate that ketones can be determined with a differential mobility spectrometry (DMS) analyzer near room temperature in the presence of elevated levels of moisture expected with the use of membrane inlets or headspace sampling of surface or ground waters. Moisture levels entering this DMS analyzer employed as an environmental monitor should be kept at 1.0 × 10 ppm or below and quantitative studies for individual ketones should be made at a fixed moisture level.
在环境压力下，对差分迁移率光谱仪的性能进行了表征，水蒸气浓度为 1.0×10 至 1.7×10 ppm，使用了从丙酮到 2-十二酮的七个酮的同系物系列。在 30°C 下，分离场为 35 至 123 Td 的分散图显示，随着水分水平的增加，水合质子、质子化单体和质子结合二聚体的α函数增加。水分水平的增加伴随着定量响应的降低，首先是质子结合二聚体的形成受到抑制，然后是质子化单体的形成受到抑制。在 4.0×10 ppm 以上的水分水平下，未观察到 2-辛酮的产物离子，这确定了观察分析物离子形成的极限。观察极限从丙酮的 1.1×10 ppm 增加到 2-十二酮的 5.7×10 ppm。这些发现表明，在使用膜入口或表面或地下水的顶空采样时，预计会存在高水平的水分的情况下，差分迁移率光谱仪（DMS）分析仪可以在接近室温的条件下测定酮。进入这种用作环境监测器的 DMS 分析仪的水分水平应保持在 1.0×10 ppm 或以下，并且应在固定水分水平下对个别酮进行定量研究。
