The effect of electrospray solvent composition on desorption electrospray ionisation (DESI) efficiency and spatial resolution
The effect of electrospray solvent composition on desorption electrospray ionisation (DESI) efficiency and spatial resolution
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DOI：
10.1039/b924208b
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发表时间：
2010-01-01
期刊：
影响因子：
4.2
通讯作者：
O'Connor, G.
中科院分区：
文献类型：
--
作者：
Green, F. M.;Salter, T. L.;O'Connor, G.
在解吸电喷雾电离（DESI）中，电喷雾和表面之间的相互作用是两个重要分析参数（空间分辨率和灵敏度）的关键。我们评估了电喷雾溶剂类型、有机溶剂与水的比例、分析物溶解度和基底润湿性对DESI侵蚀直径和材料转化为有用离子信号的影响。要做到这一点，五个氨基酸，甘氨酸，丙氨酸，缬氨酸，亮氨酸和苯丙氨酸制备为薄膜上的三个基板，紫外线/臭氧处理的玻璃，玻璃和聚四氟乙烯（PTFE）。使用四种不同的溶剂，乙腈（ACN）、甲醇（MeOH）、乙醇（EtOH）和丙-2-醇（IPA），其中有机溶剂级分具有0.1至1的水。这些模型系统允许溶解度或润湿性在其他参数变化时保持恒定。此外，与电喷雾电离（ESI）的比较允许确定电离效率的影响。结果表明，DESI效率是线性依赖于溶解度（至少对于这些材料）和分析物的溶解度低于1.5克公斤（-1），可能需要额外的策略DESI是有效的。我们表明，DESI侵蚀直径与有机溶剂分数线性提高，有机溶剂分数为0.9而不是0.5，导致2倍的改善。此外，这导致DESI效率增加35倍，DESI效率定义为每单位面积的分子离子产率。结果表明，这些改进与较小的液滴尺寸，而不是表面润湿或电离。
In desorption electrospray ionisation (DESI) the interaction between the electrospray and the surface is key to two important analytical parameters, the spatial resolution and the sensitivity. We evaluate the effect of the electrospray solvent type, organic solvent fraction with water, analyte solubility and substrate wettability on DESI erosion diameter and material transferral into useful ion signal. To do this five amino acids, glycine, alanine, valine, leucine and phenylalanine are prepared as thin films on three substrates, UV/ozone treated glass, glass and polytetrafluoroethylene (PTFE). Four different solvents, acetonitrile (ACN), methanol (MeOH), ethanol (EtOH) and propan-2-ol (IPA), are used with organic solvent fractions with water varying from 0.1 to 1. These model systems allow the solubility or wettability to be kept constant as other parameters are varied. Additionally, comparison with electrospray ionisation (ESI) allows effects of ionisation efficiency to be determined. It is shown that the DESI efficiency is linearly dependent on the solubility (for these materials at least) and for analytes with solubilities below 1.5 g kg(-1), additional strategies may be required for DESI to be effective. We show that the DESI erosion diameter improves linearly with organic solvent fraction, with an organic solvent fraction of 0.9 instead of 0.5 leading to a 2 fold improvement. Furthermore, this leads to a 35 fold increase in DESI efficiency, defined as the molecular ion yield per unit area. It is shown that these improvements correlate with smaller droplet sizes rather than surface wetting or ionisation.