Determination of five nitroimidazoles in water by liquid chromatography-mass spectrometry

A rapid liquid chromatography-mass spectrometric method for the determination of five nitroimidazoles in water from different sources is described. The extraction procedure was based on HLB solid-phase extraction with acetonitrile followed by an evaporation step. Ternidazol, another nitroimidazole, was used as the internal standard. The liquid chromatographic separation was made on a C18 bonded silica column applying a gradient with an ammonium acetate buffer solution and acetonitrile. Following electrospray ionisation, the protonated molecular ions [M+H]+ were obtained. Quantification for each nitroimidazole was carried out by monitoring its molecular ion. Calibration functions, quantification and detection limits, intra- and inter-day reproducibility and accuracy were estimated. For the confirmatory assay, several fragment ions from each nitroimidazole were obtained and monitored. The method was applied successfully to determine and identify nitroimidazoles in water from different sources at a level of 0.2 microg l(-1).