マイクロチップミセル動電クロマトグラフィーにおける新規オンライン試料濃縮法：トランジェント－トラッピング法の開発

抄録

We developed a novel on-line sample preconcentration technique named transient-trapping (tr-trapping) to improve the concentration sensitivity by using a partially injected short micellar plug in microchip micellar electrokinetic chromatography (MCMEKC). Our proposed theoretical model indicated that a trap-and-release mechanism enables a short micellar zone which was partially injected into the separation channel to work as an effective concentration and separation field. To perform tr-trapping in MCMEKC, we fabricated a 5 way-cross microchip to realize the successive injection of a shorter micellar plug and a longer sample plug. When the injection times of micelle (t_inj,M) and sample solution (t_inj,S) were 1.0 and 2.0 s, respectively, both the preconcentration and separation of two dyes were completely finished within only 4.0 s. At t_inj,S of 8.0 s, a 400-fold improvement of the detectability was achieved in comparison with conventional MCMEKC. The resolution obtained with tr-trapping-MCMEKC was also better than that with conventional MCMEKC in spite of the 160-fold shorter length of the injected micellar zone at t_inj,M of 1.0 s. These results clearly demonstrate that the tr-trapping technique in MCMEKC provides a rapid separation, high efficiency, and high sensitivity even in the short separation channel on the microchip.