Automated on-capillary isotachophoretic reaction cell for fluorescence derivatization of small sample volumes at low concentrations followed by capillary zone electrophoresis

Abstract

An automated on-line reaction cell is described combining the concentrating properties of isotachophoresis (ITP), the separation efficiency in capillary zone electrophoresis (CZE) and the detection sensitivity of laser-induced fluorescence (LIF) detection. The applicability of the reaction cell is demonstrated for an automated derivatization procedure of glutathion and several amino acids with o-phthaldialdehyde (OPA) and naphthalene-2,3-dicarboxaldehyde. Nanolitres analyte, at nanomolar concentration level, were concentrated and derivatized in capillary ITP. The derivatives were analyzed by CZE with LIF detection. The entire procedure was automated and took place in the same capillary using single capillary ITP-CZE. Furthermore, an easy applicable on-capillary OPA derivatization is described for CZE without ITP step.