Determination of amino acids in overlapped capillary electrophoresis peaksby means of partial least-squares regression

Amino acid derivatives of 1,2-naphthoquinone-4-sulfonate (NQS) can be separ ated by capillary electrophoresis at 30 kV in a fused-silica capillary by u sing a 40 mM sodium tetraborate-isopropanol (3:1, v/v) solution as backgrou nd electrolyte. This procedure was suitable for the most common amino acids . However, the peaks of three amino acids (phenylalanine, isoleucine and ty rosine) were only partially resolved and peaks of histidine and leucine der ivatives overlapped completely. Partial least-squares regression (PLS) may overcome the lack of selectivity for these amino acids. Spectroelectrophero grams of the corresponding amino acid derivative peaks were monitored with a diode-array spectrophotometer in the range 225 to 540 nm. Both spectra an d electropherograms can be used as multivariate data for further analysis. In general, the best predictions were obtained using the time domain. (C) 2 000 Elsevier Science B.V. All rights reserved.