Effect of Polar Protic and Polar Aprotic Solvents on Negative-Ion Electrospray Ionization and Chromatographic Separation of Small Acidic Molecules
Effect of Polar Protic and Polar Aprotic Solvents on Negative-Ion Electrospray Ionization and Chromatographic Separation of Small Acidic Molecules
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DOI：
10.1021/ac302397b
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发表时间：
2012-11-20
影响因子：
7.4
通讯作者：
Hughey, Christine A.
中科院分区：
文献类型：
--
作者：
Huffman, Brian A.;Poltash, Michael L.;Hughey, Christine A.
一项全面的研究调查了极性质子（甲醇和水）和极性非质子（乙腈和丙酮）溶剂对49种不同的小酸性分子的色谱分离和负离子电喷雾（ESI）响应的影响。在优化源条件和实施严格的质量控制程序（后者确保分析物响应的变化是由于测量的分析物/溶剂而不是仪器性能随时间的变化）后，使用三重四极杆上的流动注射实验测量纯溶剂中的响应。在所有溶剂中，具有吸电子基团和扩展共轭的化合物由于共振和诱导效应而电离得最好。电离是最大的在甲醇或水中的所有化合物引起的反应，从而揭示了增强的灵敏度和检测下限与极性质子溶剂实现。在流动注射实验中，丙酮中的响应等于或略低于乙腈中的响应;然而，水/乙腈和水/丙酮移动的相产生更好的色谱分离。水/甲醇产生的分离效果稍差，但总体响应最大。这种响应的增加归因于甲醇的质子性质和化合物在较高有机移动的相组成中的洗脱（保留时间与甲醇中的30%相似）。这项工作的目的是促进合理的液相色谱/质谱法的小分子应用，包括代谢组学的发展。
A comprehensive study investigated the effect of polar protic (methanol and water) and polar aprotic (acetonitrile and acetone) solvents on the chromatographic separation and negative-ion electrospray (ESI) response of 49 diverse small, acidic molecules. Flow injection experiments on a triple quadrupole were used to measure the response in neat solvents after optimization of source conditions and implementation of a rigorous quality control program (the later ensured that changes in analyte response were due to the analyte/solvent measured and not changes in instrument performance over time). In all solvents, compounds with electron-withdrawing groups and extended conjugation ionized best due to resonance and inductive effects. Ionization was greatest in methanol or water for all compounds that elicited a response, thus revealing that enhanced sensitivity and lower limits of detection are achieved with polar protic solvents. Response in acetone was equal to or slightly lower than response in acetonitrile in flow injection experiments; however, the water/acetonitrile and water/acetone mobile phases produced the better chromatographic separation. Water/methanol produced slightly less satisfactory separation but the greatest overall response. This increase in response was attributed to the protic nature of methanol and the elution of compounds in a higher organic mobile phase composition (retention times were similar to 30% later in methanol). This work is intended to facilitate rational liquid chromatography/mass spectrometry method development for small molecule applications, including metabolomics.