Micellar electrokinetic capillary chromatographic separation and fluorescent detection of amino acids derivatized with 4-fluoro-7-nitro-2,1,3-benzoxadiazole

Another method has been developed for the separation of amino acids (I min derivatization plus 22 min separation) by micellar electrokinetic capillary chromatography (MECC) with laser-induced fluorescence detection. Interesti ngly enough, such work has never been performed on essential amino acids de rivatized by 4-fluoro-7-nitro-2, 1,3-benzoxadiazole (NBD-F). Fifteen L-amin o acid standards were labelled with NBD-F at 60 degrees C for 1 min, and se parated in a buffer system containing 20 mM berate, 25 mM sodium cholate, 1 0 mM Brij 35 and 2.5% methanol. Methanol was employed to expand the MECC mi gration time window; whereas Brij 35 was used to improve the fluorescence i ntensity of amino acid derivatives. This method also indicates that bile sa lt is effective for MECC separation of ionic analytes. Surprising though, i mprovements in resolution, sensitivity and speed for amino acids analysis a re obtained in this work, which are not initially apparent in just employin g another derivatizing reagent. Under optimal conditions, 15 amino acids we re separated in a short 22 min analysis time, the shortest ever reported, a nd detection limits of nanomolar concentration and attomole mass were obtai ned. Furthermore, RSDs of migration time and peak height are better than 1% and 1.8%, respectively, again the smallest ever reported in the literature . (C) 2000 Elsevier Science B.V. All rights reserved.