Sensitive analysis of reduced glutathione in bacteria and HaCaT cells by capillary electrophoresis via online pre-concentration of transient trapping combined with the dynamic pH junction mode

A new method of capillary electrophoresis (CE) using laser induced fluorescence (LIF) detection via online pre-concentration techniques including transient trapping combined with the dynamic pH junction mode was developed for the sensitive determination of glutathione in biological samples. The mechanism together with the important parameters governing the pre-concentration and separation were investigated in order to obtain maximum resolution and sensitivity. The analytes were compressed into a narrow zone due to the effect of the dynamic pH junction mode, and then transiently trapped by SDS micelles at the interface of the sample and micellar areas. Under the optimal conditions, the limits of detection for reduced glutathione, glycine, oxidized glutathione, cysteine, and glutamic acid were 0.01, 0.01, 0.5, 0.7, and 0.1 nM (S/N = 3), respectively. The enhancement factors obtained when using the transient trapping combined with the dynamic pH junction mode as a pre-concentration process were enhanced from 87 to 430 when compared to the results obtained by the classical capillary zone electrophoresis (CZE) mode. Moreover, this optimized method was successfully applied to bacteria (Escherichia coli, Salmonella typhimurium, and Staphylococcus aureus) and HaCaT cell samples for the determination of reduced glutathione with satisfactory recoveries.