Construction and Application of a Novel Universal Detection System for High Performance Capillary Electrophoresis

Conventional high performance capillary electrophoresis (HPCE) detection modes mainly rely on chromogenic, fluorogenic, ionizable, or redox properties of analytes, greatly limiting the scope of analysis. Therefore, the development of a universal HPCE detection system has raised great attention. Herein, by tandem connection of different diameter capillaries (TCDDC), a novel and universal HPCE detection system called interface-induced current detector (IICRD) was constructed. The current signal peaks of analytes in the current-electrophoretograms (CR-EGs) can be observed for the first time. The results of detector performance tests showed good repeatability and high sensitivity. The theoretical deduction and experimental verification were further carried out. To prove the detection ability, several substances with or without special responsive groups were qualitatively and quantitatively analyzed. Firstly, cations and anions in inorganic electrolytes (inorganic salts, acids and alkalis) can be simultaneously separated and analyzed. Furthermore, several small molecular weight organic compounds, monosaccharides and disaccharides were also analyzed. The current signal peaks in CR-EGs were identified and discussed. For quantitative analysis, system suitability tests were evaluated, the results of quantitative analysis methodology validation showed that the new method was qualified for quantitative analysis. The linear relationship between the values of current intensity and the concentrations of analytes can be obtained over the investigated concentration ranges. In summary, the HPCE-DAD-IICRD system showed lower baseline noise, higher sensitivity and higher S/N especially for samples without special responsive groups, showing complementary advantages when combined with other detectors. It is expected to be a novel HPCE detection system for extensive applications.