Non-invasive characterization of stationary phases in capillary flow systems using scanning capacitively coupled contactless conductivity detection (sC~4D)

摘要

Capacitively coupled contactless conductivity detection (C~4D) has gained interest recently as an elegant new detection method for capillary electrophoresis and, to a lesser extent, liquid chromatography. However, in recent years, the versatility of this non-invasive detection system for research in materials and separation science has been demonstrated through non-traditional applications, mostly using scanning mode (sC~4D). This involves the precise measurement of local differences in the conductive response of stationary phases housed within capillary columns. sC~4D permits physical and chemical interrogation of stationary phases in capillary columns and microfluidic chips, with potential use in liquid and gas chromatography, capillary-zone electrophoresis or electrochromatography. sC~4D also allows evaluation of chemically-modified surfaces to optimize procedures, coverage and chemical or biochemical activity. This review critically summarizes these developments and highlights the potential for widespread application of sC~4D, beyond that of simple on-capillary detection.