Schoots A C, Leclercq P A
Biomed Mass Spectrom. 1979 Nov;6(11):502-7. doi: 10.1002/bms.1200061109.
After appropriate sample pretreatment and derivatization, uremic serum was investigated by combined high resolution gas chromatography and mass spectrometry, using both electron impact and chemical ionization methods. Electron impact and chemical ionization spectra of a number of identified (trimethylsilylated) carbohydrates and organic acids are compared. The utilization of chemical ionization mass spectrometry, with isobutane as the reagent gas, is discussed in detail. The influence of the reagent gas pressure on the total ion current and on the spectral appearance was studied. The identification of compounds, based on electron impact mass spectral data, was confirmed and often aided appreciably by using this technique. The chemical ionization spectra of trimethylsilyated alditols and aldonic acids, as well as of other organic acids showed protonated molecular ions, whereas aldoses did not. Differences with electron impact spectra are found mainly in the high mass region. The loss of one or more trimethylsilanol groups becomes the predominating fragmentation route at higher reagent gas pressures.
经过适当的样品预处理和衍生化后，采用电子轰击和化学电离两种方法，通过高分辨率气相色谱-质谱联用对尿毒症血清进行了研究。比较了多种已鉴定的（三甲基硅烷基化）碳水化合物和有机酸的电子轰击和化学电离光谱。详细讨论了以异丁烷作为反应气的化学电离质谱法的应用。研究了反应气压力对总离子流和光谱外观的影响。基于电子轰击质谱数据对化合物的鉴定得到了证实，并且使用该技术常常能显著地辅助鉴定。三甲基硅烷基化糖醇、糖醛酸以及其他有机酸的化学电离光谱显示出质子化分子离子，而醛糖则没有。与电子轰击光谱的差异主要出现在高质量区域。在较高的反应气压力下，一个或多个三甲基硅醇基团的丢失成为主要裂解途径。
