Microcolumn Electrophoresis for Electrokinetic Flow Analysis

ABSTRACT A 2-mm i.d. and 100-mm length electrophoretic microcolumn packed with quartz microparticles was proposed in this article. To investigate the microcolumn preparation, thermal effect and electrophoretic separation, tryptophan and tyrosine were used as the target analytes, and their separation parameters were optimized, including quartz microparticle size, buffer concentration and pH, and so on. With the 2-mm i.d. fused-silica microcolumn packed with 9 µm length uniform quartz microncrystals and the electrophoretic buffer solution of 0.75 mmol/L sodium tetraborate (pH 11.0), the thermal effect of the microcolumn electrophoresis was limited satisfactorily, and underivatized tryptophan and tyrosine were separated on baseline and detected at 224 nm by an ordinary spectrophotometer. The limits of detection for tryptophan and tyrosine were 0.018 and 0.080 µmol/L, respectively. The separation efficiency of tryptophan was 4.0 × 104 plates/m. The sample capacity of the electrophoretic microcolumn achieved 3...