A Novel Capillary Electrophoresis-Chemiluminescence System for Separation and Detection of Amino Acids
A peroxyoxalate-based chemiluminescence(CL) detection following capillary electrophoresis(CE) separations for assaying amino acids is described.To achieve high signal stability and sensivity,a new interface was designed including a new mixing mode and a new grounding electrode mode.A platinum wire-connected cathode of a high voltage source was put onto a stainless steel needle tube,which was used as grounding electrode.The CE capillary was inserted into the stainless steel needle tube and the capillary outlet was put on the outlet of the needle tube.The CE capillary and two reagent capillaries used for delivering chemiluminescence reagent were fixed oppositely to a reaction cell.Amino acids fluorescently tagged with dansyl chloride and naphthalene-2,3-dicarboxaldehyde(NDA) were used for the study.Results show this CE-CL system has good stability,resolution,sensitivity and reproducibility.The detection limits were 1.1 nmol/L for dansyl-leucine(Leu) and 2.0 nmol/L for dansyl-aspartic acid(Asp).The relative standard deviations of peak height and migration time were 2.3%-3.8% and 1.2%-1.5%,respectively.