Institute of Analytical Chemistry of the Academy of Sciences of the Czech Republic, Veveří 97, CZ-60200 Brno, Czech Republic.
J Chromatogr A. 2012 Apr 20;1234:32-7. doi: 10.1016/j.chroma.2011.11.035. Epub 2011 Nov 26.
This contribution presents an experimental approach for improvement of analytical performance of electromembrane extraction (EME), which is based on the use of stabilized constant d.c. electric current. Extractions were performed using a high voltage power supply, which provided stabilized constant d.c. current down to 1μA and facilitated current-controlled transfer of ions of interest from a donor solution through a supported liquid membrane (SLM) into an acceptor solution. Repeatability of the extraction process has significantly improved for EME at constant electric current compared to EME at constant voltage. The improved repeatability of the extraction process was demonstrated on EME-capillary electrophoresis (EME-CE) analyses of selected basic drugs and amino acids in standard solutions and in human urine and serum samples. RSD values of peak areas of the analytes for EME-CE analyses were about two-fold better for EME at constant electric current (2.8-8.9%) compared to EME at constant voltage (3.6-17.8%). Other analytical parameters of the EME-CE methods, such as limits of detection, linear ranges and correlation coefficients were not statistically different for the two EME modes. Moreover, EME at constant electric current did not suffer from SLM instabilities frequently observed for EME at constant voltage.
本研究提出了一种改进电迁移萃取（EME）分析性能的实验方法，该方法基于使用稳定的直流电流。采用高压电源进行萃取，该电源可提供稳定的直流电流，低至 1μA，并有利于电流控制将感兴趣的离子从供体溶液通过支撑液膜（SLM）转移到受体溶液中。与恒电压 EME 相比，恒电流 EME 显著提高了萃取过程的可重复性。在标准溶液和人尿、血清样品中，通过 EME-毛细管电泳（EME-CE）分析对选定的碱性药物和氨基酸进行了实验，验证了萃取过程的可重复性得到了改善。与恒电压 EME 相比（3.6-17.8%），恒电流 EME 的分析物峰面积的 RSD 值要好两倍左右（2.8-8.9%）。两种 EME 模式下，EME-CE 方法的其他分析参数，如检测限、线性范围和相关系数没有统计学差异。此外，恒电流 EME 不会像恒电压 EME 那样经常出现 SLM 不稳定的问题。
