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电子轰击、化学电离和场电离质谱由于要求样品在电离前气化,不适于分析极性高的热不稳定化合物。场解吸电离法的出现扩大了质谱的应用范围。现在,场解吸电离法与高场强度磁铁配合,可以分析分子量为3000的化合物。但是应当指出,场解吸电离法还是有局限性的。用场解吸法得到的谱图随分析时间改变,重现性差;实验操作难度大,不容易掌握;碎片离子峰少,提供的结构信息少;解吸需要一定的加热电流,从而使一些化合物发生热分解;对于一些极性特别大的化合物,场解吸法也无能为力。
Electron bombardment, chemical ionization, and field ionization mass spectrometry are not suitable for the analysis of highly polar thermally unstable compounds because they require the sample to be gasified prior to ionization. The emergence of field desorption ionization has expanded the application of mass spectrometry. Field Desorption Ionization now works with high field strength magnets to analyze compounds with a molecular weight of 3000. However, it should be noted that field desorption ionization is still limited. The spectrum obtained by the field desorption method changed with the analysis time, and the reproducibility was poor. The experimental operation was difficult and not easy to grasp. The fragmentation ion peak was less and provided less structural information. Desorption required a certain heating current to cause some compounds to thermally decompose For some very polar compounds, field desorption can not do anything.