Development and validation of a multiclass method for the determination of organohalogen disinfectant by-products in water samples using solid phase extraction and gas chromatography-tandem mass spectrometry.

An analytical method employing solid phase extraction (SPE) and gas chromatography-tandem mass spectrometry (GC-MS/MS) has been developed for quantitative determination of twenty-six organohalogen disinfectant by-products (OXBPs) in water samples. Target analytes include four trihalomethanes (THMs), four iodohalomethanes (I-HMs), one haloacetaldehyde (HAL), six haloketones (HKs), four halonitromethanes (HNMs), and seven haloacetonitriles (HANs). The sample preparation procedure includes pretreatment with ascorbic acid to quench residual oxidants, followed by analyte enrichment using solid-phase extraction. Five SPE sorbents were tested. The best results for the majority of target analytes were obtained using a styrene-divinylbenzene copolymer phase and methyl tert-butyl ether (MTBE) as the elution agent. GC-MS analysis was performed using electron ionization (EI) and selected reaction monitoring (SRM) for analyte detection. The performance of the method was assessed according to the French standard NF T90-210. The method showed LOQs ranging from 3 to 3000 ng L-1. The applicability of the method has been demonstrated by analyzing both river water and tap water samples. The OXBPs detected most often in the tap water were dibromochloromethane (in 100% of the samples, 4.3-4.7 μg L-1), bromodichloromethane (100%, 1.3-1.7 μg L-1), tribromomethane (100%, 0.8-4.4 μg L-1), trichloromethane (100%, 0.6-0.7 μg L-1), dibromoacetonitrile (75%, 0.5-0.9 μg L-1), with dichloroacetonitrile and 1,1,1-trichloro-2-propanone detected at concentrations around the LOQ levels. In the treated river water samples, the only OXBPs measured at levels above the limit of quantification were trichloromethane and 1,1,1-trichloro-2-propanone. To the best of our knowledge, this is the first SPE-GC-MS/MS method enabling the analysis of an extensive list of OXBPs.