Aguilar C, Borrull F, Marcé R M
Department of Analytical Chemistry and Organic Chemistry, Universitat Rovira i Virgili, Tarragona, Spain.
J Chromatogr A. 1998 May 1;805(1-2):127-35. doi: 10.1016/s0021-9673(98)00039-9.
Liquid chromatography-mass spectrometry (LC-MS) with a particle beam (PB) interface is used to separate and identify a group of pesticides. The mass spectra obtained under the different ionization modes, electron ionization (EI) and positive and negative chemical ionization (PCI and NCI) are compared. The operating conditions under each mode, determined by studying the influence on the ion abundance of the ion source temperature of the EI mode, and the gas pressure and ion source temperature in the methane CI were optimized. EI was more sensitive than PCI and NCI and of the latter two modes, NCI gave higher responses, especially for organophosphorus compounds. When on-line solid-phase extraction-LC-PB-MS was applied to real samples, limits of detection in full scan mode were in the range of 0.5 and 10 micrograms l-1 for EI. The analysis of real samples by on-line solid-phase extraction-LC-PB-MS enabled EI detection of one of the pesticides studied and confirmation by PCI and NCI. The combined EI/CI information also enabled the detection of some non-target compounds.
采用带粒子束（PB）接口的液相色谱-质谱联用（LC-MS）技术对一组农药进行分离和鉴定。比较了在不同电离模式下获得的质谱图，即电子电离（EI）、正化学电离（PCI）和负化学电离（NCI）。通过研究EI模式下离子源温度对离子丰度的影响以及甲烷CI中的气压和离子源温度，优化了每种模式下的操作条件。EI比PCI和NCI更灵敏，在PCI和NCI这两种模式中，NCI的响应更高，尤其是对有机磷化合物。当在线固相萃取-LC-PB-MS应用于实际样品时，EI全扫描模式下的检测限在0.5至10微克/升范围内。通过在线固相萃取-LC-PB-MS对实际样品进行分析，EI能够检测到所研究的一种农药，并通过PCI和NCI进行确证。EI/CI组合信息还能够检测到一些非目标化合物。
