High-performance liquid chromatography with post-column chemiluminescence detection for simultaneous determination of trace N-nitrosamines and corresponding secondary amines in groundwater

Abstract

A sensitive, selective and reliable high-performance liquid chromatographic method with chemiluminescence detection is described for the determination of trace N-nitrosamines and corresponding secondary amines simultaneously in environmental water samples. The method combines solid-phase extraction on to a mini activated carbon column, followed by elution with acetone and concentration of the extracts by denitrosation and fluorogenic derivatization. The separation of derivatives was performed on a C₁₈ column (3µm, 83 × 4.6 mm id) with a mobile phase consisting of acetonitrile-water-ethanol (63.5 + 35.5 + 1.0 v/v) containing 3.0 mmol l^–1 imidazole and 0.5 mmol l^–1 oxalic acid and with a pH of 6.2. Peroxyoxalate chemiluminescence detection was carried out by using bis(2-nitrophenyl) oxalate and hydrogen peroxide as chemilumigenic reagents. The quantitative data obtained (calibration graphs, detection limits, etc.) were analogous to those published previously. Groundwater samples were analysed using the proposed method. Data including the total amounts of secondary amines plus N-nitrosamines, the amount of secondary amines and results of blank experiments from the chromatograms for individual water sample were calculated, then the final concentrations of N-nitrosamines and secondary amines in each water sample were obtained simultaneously. The application of this procedure for determination of N-nitrosamines and corresponding secondary amines in water samples at pmol l^–1 and fmol l^–1 levels was successfully achieved. The recoveries of various N-nitrosamines and secondary amines added to groundwater samples were excellent (95% for all except two).