毛细管直接进样质谱仪在液体样品分析中的应用

Application of Capillary Introduction Mass Spectrometer to Direct Analysis of Liquid

毛细管进样是目前小型质谱中常见的进样方式,它主要用于在大气压条件下对气态样品直接进行成分分析。本研究将自行搭建的一台基于毛细管进样和电子轰击电离源的小型四极杆质谱仪用于液体样品的分析研究,主要通过对甲苯样品的测定来验证液体直接进样分析方法的可行性。液体进样的方式能防止大气采样过程中空气的摄入,降低谱图上空气背景的干扰。结果表明,采用5μm内径的进样毛细管时,仪器能直接用于对液体样品的分析。此外,实验中还通过在毛细管上施加高电压的方式使采集的液体形成电喷雾,以此来促进液体的气化过程,使样品更易于被电离,这一方案能显著提高仪器的检测效率和灵敏度。

Capillary introduction was widely employed in miniature mass spectrometer to permit atmospheric sampling of gas analyte.Feasibility of direct liquid analysis using capillary introduction mass spectrometer was explored in this study.All the experiments were carried out on a newly developed miniature mass spectrometer,which consisted of a capillary interface,an electron impact ionization source and a quadrupole analyzer.Direct analysis of liquid conduced to the decrease of air injection,hence air interference could be effectively reduced even the analysis was performed at atmosphere.The results indicated that the miniature mass spectroemter was capable of performing direct analysis of liquid when a 5-μm capillary was used as the sampling interface.Furthermore,to improve the ionization efficiency of analyte,electrospray was used as a nebulization technique to transfer liquid sample into aerosol,which could evidently increase the sensitivity.