Resolution of overlapped peaks of amino acid derivatives in capillary electrophoresis using multivariate curve resolution based on alternating least squares

The application of chemometric techniques to the resolution of overlapped p eaks in capillary electrophoresis (CE) is described. When a physical separa tion can not be completely accomplished, chemometrics might still resolve t he determination of the analytes mathematically. CE with diode array detect ion can provide a large amount of data consisting of spectra registered ove r time. in this study, the capillary electrophoretic separation of 1,2-naph thoquinone-4-sulfonate derivatives of amino acids is studied. Most of the c ommon amino acid derivatives can be separated at 30 kV in a fused-silica ca pillary by using a 40 mM sodium tetraborate + isopropanol (3:1 v/v) solutio n as background electrolyte. However, peaks of certain derivatives (Phe, Hi s, Leu and lie) still overlap. A multivariate curve resolution method based on an alternating least squares optimization procedure is used for the res olution of the overlapped electrophoretic peaks. The method takes advantage of spectral and electrophoretic differences of analytes to recover their p ure electrophoretic and spectral profiles. In addition, each analyte in the mixture can be quantified using the corresponding standards.