Comparison of reversed-phase liquid chromatography-mass spectrometry with electrospray and atmospheric pressure chemical ionization for analysis of dietary tocopherols
Comparison of reversed-phase liquid chromatography-mass spectrometry with electrospray and atmospheric pressure chemical ionization for analysis of dietary tocopherols
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DOI：
10.1016/j.chroma.2007.04.058
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发表时间：
2007-07-20
影响因子：
4.1
通讯作者：
Jastrebova, Jelena A.
中科院分区：
文献类型：
--
作者：
Lanina, Svetlana A.;Toledo, Patricia;Jastrebova, Jelena A.
评估了负离子和正离子模式下的 ESI 和 APCI 电离技术，以同时对四种生育酚同系物（α、β、γ 和 δ）进行 LC-MS 分析。正离子模式下生育酚的 ESI 和 APCI 电离效率不高，并且通过两种竞争机制进行，形成质子化的伪分子离子和分子离子，这对 MS 信号的重复性产生不利影响。 ESI 和 APCI 中负离子模式的电离效率更高，因为它仅产生目标去质子化的伪分子离子。与负离子 ESI 相比，负离子模式下的 APCI 表现出更大的线性范围、更低的检测限，并且对分析物的化学结构差异和所用溶剂的性质不太敏感。因此，选择负离子 APCI 来开发同时测定食品中四种生育酚的 LC-MS 方法。在新型五氟苯基硅胶基 Fluophase PFP 色谱柱上实现了生育酚的基线分离。使用甲醇-水（95:5，v/v）作为流动相优于使用乙腈-水，这可以使 MS 信号获得相当大的增益。当注射 2 μL 时，α-生育酚的定量限为 9 ng/mL，β-和γ-生育酚的定量限为 8 ng/mL，δ-生育酚的定量限为 7.5 ng/mL。该方法成功应用于葵花籽油和牛奶中生育酚的测定。 (c) 2007 Elsevier B.V. 保留所有权利。
ESI and APCI ionization techniques in both negative and positive ion modes were evaluated for simultaneous LC-MS analysis of the four tocopherol homologues (alpha,beta,gamma and delta). The ESI and APCI ionization of tocopherols in positive ion mode was not efficient and proceeded via two competitive mechanisms, with the formation of protonated pseudo-molecular ions and molecular ions, which adversely influenced the repeatability of MS signal. Ionization in negative ion mode in both ESI and APCI was more efficient as it only produced target deprotonated pseudo-molecular ions. The APCI in negative ion mode showed larger linearity range, lower detection limits and was less sensitive to the differences in chemical structure of analytes and nature of applied solvents than negative ion ESI. Negative ion APCI was, therefore, chosen for the development of LC-MS method for simultaneous determination of the four tocopherols in foods. A baseline separation of the tocopherols was achieved on novel pentafluorophenyl silica-based column Fluophase PFP. The use of methanol-water (95:5, v/v) as a mobile phase was preferable to the use of acetonitrile-water clue to considerable gain in MS signal. The limits of quantifications were 9 ng/mL for alpha-tocopherol, 8 ng/mL for beta- and gamma- and 7.5 ng/mL for delta-tocopherol when 2 mu L was injected. This method was successfully applied to determination of tocopherols in sunflower oil and milk. (c) 2007 Elsevier B.V. All rights reserved.