Determination of 2,6-dichlorobenzamide and its degradation products in water samples using solid-phase extraction followed by liquid chromatography–tandem mass spectrometry

Abstract

An analytical method was developed for the determination of 2,6-dichlorobenzamide (BAM) and five degradation products thereof including 2-chlorobenzamide (OBAM), 2,6-dichlorobenzoic acid (DCBA), 2-chlorobenzoic acid (OBA), benzoic acid (BA) and benzamide (BAD) in water samples. Solid-phase extraction was combined with liquid chromatography coupled to tandem mass spectrometry using electrospray ionisation. Groundwater spiked at a concentration of 1.0 μg/L gave recoveries on day 1 between 91 and 102% (relative standard deviation: 2.2–26.5%) for OBAM, BAM, DCBA, BA and OBA, while BAD showed a somewhat lower recovery of 60% (relative standard deviation: 25%). Corresponding figures on day 3 gave recoveries of 97–110% (relative standard deviation: 3–22%) for OBAM, BAM, DCBA, BA and OBA, while BAD had a recovery of 51% (relative standard deviation: 4%). The final SPE-LC–MS/MS method had a LOD Method of 0.009, 0.007, 0.010, 0.021, 0.253 and 0.170 μg/L groundwater for BAD, OBAM, BAM, DCBA, BA and OBA and a LOQ Method of 0.030, 0.023, 0.035, 0.071, 0.842 and 0.565 μg/L groundwater in the same order of appearance. Analysis of three different Danish groundwaters confirmed the occurrence of BAM at levels exceeding the threshold value of 0.1 μg/L, while no degradation products were found above LOD Method.