Separation of carbonyl 2,4-dinitrophenylhydrazones by capillary electrochromatography with diode array detection

The applicability of capillary electrochromatography (CEC) with photodiode array detection for the analysis of carbonyl hydrazones is presented. The C EC separation of thirteen hydrazones was optimized by a systematic variatio n of conditions using a commercially available CE system and a 3-mu m porou s C-18-bonded silica capillary column. The separation profile obtained unde r optimal isocratic conditions (60% actonitrile-4% tetrahydrofuran-5 mM Tri s, pH 8) is similar to those reported for gradient HPLC, with significant i mprovements in efficiency (to 150 000-250 000 theoretical plates/m) and ana lysis time (by a factor of 4). The retention time reproducibility is better than 0.2% (RSD) from run to run and 1% from day to day. The limits of dete ction for individual carbonyl hydrazones range between 0.1 and 0.5 mu g/ml. Applications to ambient air and automobile exhaust are shown. (C) 1999 Els evier Science B.V. All rights reserved.