IMPROVEMENT OF LASER-INDUCED FLUORESCENCE DETECTION OF AMINO-ACIDS IN CAPILLARY ZONE ELECTROPHORESIS

Laser-induced fluorescence detection in capillary zone electrophoresis of fluorescein isothiocyanate (FITC I)-derivatized amino acids is a very sensitive detection technique. Unfortunately, the excess of FITC I and additional compounds interferes with the separation and detection of the amino acids. Therefore, the interferences were minimized by using optimal derivatization conditions. A liquid ion-exchange resin LA-2 was used to extract FITC I from the sample solution after derivatization. A better long-term stability was one of the results we obtained from optimizing the extraction step. The separations of the FITC-amino acids were performed in berate buffer solution of pH 9.5. Not all amino acids can be separated completely. The detection limits of two selected compounds, proline and arginine, were 0.3 and 0.5 nM, respectively.