Derivatization at capillary inlet in high-performance capillary electrophoresis - Its reliability in quantification

The possibility of using derivatization at the capillary inlet for quantitative analysis by capillary electrophoresis was explored using amino acids as model compounds. It was shown that by using an appropriate introduction reagent and sample introduction program, i.e. reagent, then sample and once again reagent (so-called sandwich mode), selected amino acids were derivatized in high yields with o-phthalaldehyde as in pre-capillary derivatization. Analyses of a number of amino acids by this at-inlet derivatization technique, followed by separation in a low pH phosphate buffer containing CHAPS, demonstrated the efficacy of this technique in automated amino acid analysis.