Determination of dimethylamine and other low-molecular-mass amines using capillary electrophoresis with laser-induced fluorescence detection.

The potential of capillary electrophoresis (CE) with laser-induced fluorescence (LIF) detection for the separation and determination of dimethylamine (DMA) and other low-molecular-mass amines involving precolumn derivatization with fluorescein isothiocyanate isomer I (FITC) was investigated. Different variables that affect derivatization (pH, FITC concentration, reaction time and temperature) and separation (buffer concentration, addition of various organic modifiers, applied voltage and length of capillary) were studied. The linearity, reproducibility and reliability of the method were evaluated. The estimated instrumental detection limit for a 2-s pressure injection of the FITC-DMA derivative was 50 pg/ml (10(-9) M), using LIF detection with excitation and emission wavelengths of 488 nm and 520 nm, respectively. However, for practical reasons, a minimum of 5 ng/ml DMA should be subjected to the derivatization. The applicability of the described method to the extract of atmospheric aerosol samples was demonstrated.