Miniature differential mobility spectrometry using atmospheric pressure photoionization
Miniature differential mobility spectrometry using atmospheric pressure photoionization
复制标题
DOI：
10.1021/ac052213i
复制
发表时间：
2006-07-01
影响因子：
7.4
通讯作者：
Stone, John A.
中科院分区：
文献类型：
--
作者：
Nazarov, Erkinjon G.;Miller, Raanan A.;Stone, John A.
正、负离子谱已获得与微型差分迁移率谱仪配备了光电离源在大气压下工作。以苯为掺杂剂，C6 H6+为反应离子，甲基膦酸二甲酯与丁酮反应得到质子化分子离子和质子结合二聚体离子。从气相色谱注射芳烃，苯，甲苯，和二甲苯，产生的分子离子时，水分含量非常低，但在高水平的水合质子也存在的光谱。质子化产物的形成可能的机制进行了讨论。以苯或丙酮为掺杂剂，用六氟化硫捕获电子产生负离子。二氧化氮的光电离导致硝酸根离子的形成，其产率是浓度的非线性函数。使用合适的掺杂剂增强离子形成高达2个数量级，并且在正模式和负模式中的检测限都在亚ppmv水平。该研究为使用光电离源作为放射性Ni-63源的替代品提供了强有力的理由。
Positive and negative ion spectra have been obtained with a miniature differential mobility spectrometer equipped with a photoionization source operating at atmospheric pressure. With benzene as a dopant, providing C6H6+ as reactant ion, protonated molecular ions and proton-bound dimer ions were obtained with dimethyl methylphosphonate and butanone. The spectra obtained from gas chromatographic injections of aromatic hydrocarbons, benzene, toluene, and the xylenes, produced the molecular ions when the moisture level was very low, but at a high level the hydrated proton was also present. Possible mechanisms for the formation of protonated products are discussed. Negative ions were produced from electron capture by sulfur hexafluoride using benzene or acetone as dopant. Photoionization of nitrogen dioxide led to the formation of the nitrate ion whose yield was a nonlinear function of concentration. The use of a suitable dopant enhanced ion formation by up to 2 orders of magnitude, and limits of detection in both the positive and negative modes were all at the sub ppmv level. The study makes a strong case for the use of a photoionization source as an alternative to the radioactive Ni-63 source.