采用柱后抑制器技术降低流动相中三氟乙酸对质谱信号抑制作用的研究

研究柱后抑制器(CSRS)技术有效降低流动相中三氟乙酸(TFA)对质谱信号的抑制.采用双三元液相系统,左泵以反相模式分离细胞色素C酶解肽段(流动相含0.1%TFA,流速0.25 m L/min),柱后选择CSRS作为抑制器.同时右泵提供碳酸氢铵(浓度为0.05 mol/L,流速1.00 m L/min)作为再生液.碳酸氢铵和三氟乙酸在抑制器CSRS中通过阴离子交换膜进行离子交换,降低流动相中TFA离子抑制效应,提高肽段在质谱上的响应(S/N提高1~16倍).采用柱后抑制器技术对硫酸依替米星主成分及杂质进行定性分析(0.2 mol/L TFA),流动相经过抑制器后由强酸性变成中性,实现样品在LC和MS之间无缝连接分析.

Enhancement of Sensitivity for Bioanalysis by Liquid Chromatography-Electrospray Mass Spectrometry with Trifluoroacetic Acid in Mobile Phase Using a Suppressor

A method is described to improve the sensitivity of biological samples in LC-MS which contains trifluoroacetic acid(TFA) in the mobile phase by adding a suppressor (CSRS Ultra II) after the column. The method is developed on dual-gradient liquid chromatographic(DGLC) systems. And one peptide sample hydrolyzed by cytochrome C was analyzed on the left pump by the reversed phase model where the mobile phase contained 0.1 % TFA and the flow rate was 0.25 mL/min. 0.05 mol/L ammonium bicarbonate solution was delivered by the right pump with a flow rate of 1.00 mL/min. The two mobile phases converged in the post-column suppressor after which the concentration of TFA was reduced. As a result, the signal of peptide analyzed by MS improved about 1-fold to 16-fold. Using this method, the qualitative analysis of impurities in etimicin sulfate drug was perfectly achieved without any additional operations between LC and MS.