纸喷雾软电离质谱分析性能研究.

Paper spray mass spectrometry has received considerable attentions in recent years due to its simple operation, low cost and without tedious sample pretreatment prior to analysis. However, paper spray ionization (PSI) as a type of electrospray-based ionization source, there are few reports on exploring the ionization performance differences between it and two frequently used electrospray ionization (ESI) and nanoelectrospray ionization (nanoESI). Herein the ionization performance of above three ionization sources was compared systematically by using gasolines, myoglobin, cytochrome c and glycidyl azide polymer (GAP) as samples. According to the obtained results, the ionization performance demonstrated the following trend: PSI<ESI<nanoESI, in which PSI gave the softest ionization performance relative to other two ionization sources. Specifically, when commercially available 92# and 95# (Research Octane Number, RON) gasolines were used for analysis, PSI was favorable to give more intensive peaks for stronger polar compounds, whereas more abundant peaks for weaker polar compounds were observed in mass spectra by ESI and nanoESI. When proteins such as myoglobin and cytochrome c were ionized, the charge state distribution (CSD) for PSI moved to higher mass-to-charge ratios relative to ESI and nanoESI, and the average charge states (Zave) from PSI were lower than those from ESI and nanoESI. As an example for myoglobin, the Zave value was 18.07±0.01 for PSI, whereas the corresponding values were 19.47±0.01 (ESI) and 19.67±0.01 (nanoESI) in comparable experimental conditions (n=3), respectively. When cytochrome c was used for analysis, the Zave values were 14.14±0.17 (PSI), 14.44±0.13 (ESI) and 14.67±0.01 (nanoESI), respectively. As GAP sample was analyzed using PSI, it was more favorable to maintain the structures of intact GAP, and both the number.average molecular weight (Mn) and weight-average molecular weight (Mw) had higher values. For both ESI and nanoESI, lower values of Mn and Mw were obtained. These results provided confident evidences that the performance of PSI was much softer in ionizing different types of compounds than those of ESI and nanoESI. The investigation on the performance of various ionization sources can provide important references for deep understanding of the ionization performance of PSI, ESI and nanoESI as well as broadening the application of PSI source. [ABSTRACT FROM AUTHOR]