电喷雾离子源(Electrospray Ionization source,ESI)可以很方便地分析极性物质,但难以分析非极性物质,而离子源的切换是一件麻烦的工作。我们尝试改造常规ESI成电晕喷雾离子源(Coronal Spray Ionization source,CSI),使它也能够分析非极性物质,检测器为一台飞行时间质谱仪。我们将高达2 500~5 000伏特的高压加到一根60μm内径的不锈钢毛细管上,将其作为电喷雾源。当加的高压高达3 500伏特或以上时,在不锈钢管尖端会出现微小的电晕,这部分电晕的作用便是用来电离弱极性或是非极性物质。通过调节加到不锈钢管上的电压,这套装置可以检测到不同种类的弱极性物质,而不需要对装置本身做太多的改动或是卸掉仪器的真空。我们在这套CSI上成功测到了萘和芘,而ESI无法检测出这两种物质。另外我们将其信号强度与APCI对比,发现在同一数量级上。Electrospray Ionization source(ESI)can easily analyze polar compounds,but it is hard for it to detect non-polar compounds.Meanwhile,it will be a hasty job to change ion sources during analysis.We tried to transform an easily built ESI into a Coronal Spray Ionization(CSI)source,which is able to detect non-polar compounds,and fabricated it to a quadrupole time-offlight mass spectrometer(QTOFMS).High voltage was applied to a 60μm I.D.steel needle serving as the spray needle.When the voltage was above 3 500 volts,a tiny corona area would appear around the tip of the needle,acting as the way to ionize weakly polar and non-polar compounds.By adjusting the applied voltage,substances with different polarities could be detected by the same apparatus without breaking the vacuum or making too much alternation to instrument.We successfully detected pyrene and naphthalene in CSI,which couldn't be detected by ESI.We also got that their signal intensities in CSI were in the same order of magnitude with those in APCI.All the results indicate the CSI is a potential good method to analyze non-polar compounds.国家自然科学基金项目(20775063,21027011)资
