Fully automated determination of N-nitrosamines in environmental waters by headspace solid-phase microextraction followed by GC-MS-MS

摘要

A fully automated method for determining nine Environmental Protection Agency N-nitrosamines in several types of environmental waters at ng/L levels is presented. The method is based on a headspace solid-phase microextraction followed by GC-MS-MS using chemical ionization. Three different fibers (carboxen/PDMS, divinylbenzene/carboxen/PDMS, and PEG) were tested. Solid-phase microextraction conditions were best when a divinylbenzene/carboxen/PDMS fiber was exposed for 60 min in the headspace of 10 mL water samples at pH 7 containing 360 g/L of NaCl, at 45°C. All compounds were analyzed by GC-MS-MS within 18 min. The method was validated using effluent from an urban wastewater treatment plant and the LODs ranged from 1 to 5 ng/L. The method was then applied to determine the N-nitrosamines in samples of different complexities, such as tap water and several influent and effluent wastewater samples from urban and industrial wastewater treatment plants and a potable water treatment plant. Although the analysis of influent industrial wastewater revealed high concentrations of some compounds (N-nitrosomorpholine and N-nitrosodimethylamine at μg/L levels), in industrial effluents and other samples, the concentrations were substantially lower (ng/L levels). The new method is suitable for the simple and reliable determination of N-nitrosamines in highly complex water samples in a completely automated procedure.