胆甾相液晶的质谱研究——Ⅰ.EI、FD和CI质谱的比较

Mass Spectrometry Research of Cholesteric Liquid Crystals Ⅰ. Comparison of EI, FD and CI Mass Spectra

研究了胆甾醇酯类和胆甾醇卤代物的电子轰击电离(EI)、场解吸电离(FD)、化学电离(CI)的质谱。结果表明:胆甾醇酯的EI质谱裂解途径主要由甾环决定,各化合物谱图之间几乎无差别;FD质谱能提供清晰的分子量信息和表征甾环结构的碎片离子峰(m/e 369);CI质谱除了具有FD质谱特征外,大部分还能提供RCOOH结构信息。三种质谱并用,能有效地测试液晶化合物。

Mass spectra (MS) of cholesterol esters and halides were obtained by means of Electron Impact (EI), Field Desorption (FD) and Chemical Ionization (CI). The result shows that EI fragmentation process of cholesterol esters is determined mostly by the steroid nucleus, and there is almost no difference among the mass spectra of various compounds. FD-MS can supply both clear imformation of molecular weights of compounds and a fragment ion at m/e 369 due to the steriod nucleus. Besides having the same feafures as that of FD-MS, CI-MS of most compounds yield information of RGOOH structure. Therefore, mass spectra gained by these three ionization modes are satisfactorily used to analyse liquid crystals.