Premium
Hydrophobic labeling of amino acids: Transient trapping–capillary/microchip electrophoresis
Author(s) -
Sueyoshi Kenji,
Hashiba Kota,
Kawai Takayuki,
Kitagawa Fumihiko,
Otsuka Koji
Publication year - 2011
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/elps.201000567
Subject(s) - chemistry , chromatography , capillary electrophoresis , analyte , micellar electrokinetic chromatography , trapping , derivatization , bodipy , reagent , detection limit , electrophoresis , fluorescence , analytical chemistry (journal) , mass spectrometry , ecology , physics , quantum mechanics , biology
Transient trapping (tr‐trapping) was developed as one of the on‐line sample preconcentration techniques to improve a low concentration‐sensitivity in microchip electrophoresis (MCE), providing highly effective preconcentration and separation based on the trap‐and‐release mechanism. However, a poor performance to hydrophilic analytes limited the applicability of tr‐trapping. To overcome this drawback, tr‐trapping was combined with a sample labeling using a hydrophobic reagent in CE. Three commercially available fluorescent dyes, fluorescein isothiocyanate, succinimidyl esters of Alexa Fluor 488 and BODIPY FL‐X, were tested as derivatization reagents to increase the hydrophobicity of amino acids (AAs) that were undetectable due to no fluorescence/UV‐absorbance. As a result, it was confirmed that BODIPY labeling allowed various AAs to be analyzed in tr‐trapping–micellar electrokinetic chromatography (tr‐trapping–MEKC) by the increase in the hydrophobicity. In tr‐trapping–MEKC, both the improvement of the resolution and 106–125‐fold enhancements of the detectability of labeled AAs were achieved relative to the conventional capillary zone electrophoresis. The limit of detection of labeled phenylalanine was improved from 800 to 5 pM by applying tr‐trapping–MEKC. In tr‐trapping–microchip MEKC, furthermore, an 80–160‐fold enhancement of the peak intensity and a baseline separation was also achieved within 30 s. These results clearly demonstrate that the tr‐trapping technique with hydrophobic labeling will make CE/MCE more sensitive for various analytes.