| Résumé | Integration of a packed column onto a microchip for performance of capillary electrochromatography (CEC) is described. The quartz device incorporated a cross-injector, and a double weir trapping design for formation of 1, 2 and 5?mm long CEC columns. Three fluorescent dyes were baseline-resolved with plate numbers of 330 (330?000 plates/m; height equivalent to a theoretical plate, H = 3.0 mum) for BODIPY 493/503, 360 (360?000 plates/m; H = 2.8 mum) for rhodamine 123 and 244 (244?000 plates/m; H?=?4.1?mum) for acridine orange (AO) with 500?V applied on a 1?mm long column. The 2?mm column yielded sim1.8 times more theoretical plates than did the 1?mm column, when operated at the same flow rate. Van Deemter plots were obtained for the three column lengths, showing increased plate height for the 5?mm length. A 2?mm column gave peak height and area relative standard deviation (RSD) values of 2.5 and 3.3%, respectively, as averages for the three dyes (n = 15). The RSD for the dye retention times was 1% (n = 6) over one day, and 3% (n = 30) over five days. Indirect fluorescence detection of thiourea and of amino acids was possible using a neutral indicator dye (BODIPY 493/503), with a detection limit of 10 muM for amino acids. |
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