Separation of amino acids and amines by capillary electrophoresis using poly(ethylene oxide) solution containing cetyltrimethylammonium bromide

We describe simultaneous analysis of naphthalene-2,3-dicarboxaldehyde (NDA)-amino acid and amine derivatives by capillary electrophoresis in conjunction with light-emitting diode-induced fluorescence (LEDIF) detection using poly(ethylene oxide) (PEO) containing cetyltrimethylammonium bromide (CTAB). In the presence of CTAB and acetonitrile (ACN), adsorption of PEO on the capillary wall is suppressed, leading to generation of a fast and reproducible electroosmotic flow (EOF). In order to optimize separation resolution and speed, 100 mM Tris–borate solution (pH 7.0) containing 20 mM CTAB and 25% ACN was used to fill the capillary and to prepare 1.2% PEO that entered the capillary via EOF. The analysis of 14 NDA-amino acid and -amine derivatives by this approach is rapid (< 4 min), efficient ((0.9–6.4) × 10⁵ theoretical plates), and sensitive (the LODs (S/N = 3) range from 9.5 to 50.5 nM). The RSD values (n = 5) of the migration times and peak heights of the analytes for the intraday analysis are less than 1.5 and 1.2%, respectively. We have validated the practicality of this approach by quantitative determination of 10 amino acids and amines in a beer samples within 4 min.