超音速分子線法を試料導入系とするガスクロマトグラフ質量分析計の試作研究

抄録

The effect of vibrational supercooling in supersonic molecular beam (SMB) on the electron impact mass spectrometry (EIMS) was demonstrated for a number of organics, (i) hydrocarbons, (ii) monoterpenes, and (iii) fatty acid esters. With SMB/EIMS, all of these compounds showed enhanced molecular ion, and their conventional fragmentation patterns were retained at smaller intensities whereas the fragment ion intensities were greatly suppressed.
Effect of impact electron impact energy was also examined. With increase in electron energy, fragment ion intensity increased for (i) hydrocarbon and (ii) aliphatic alcohol, whereas fatty acid methyl ester showed opposite behavior. At 20 eV, peak intensities of McLafferty rearrangement (m/z 74) and molecular ion were 100 % and 55 %, respectively, whereas at 70 eV, they were 25 % and 100 %, respectively. Sensitivity for GC/MS mode was also examined.