Determination of nine N-nitrosamines in water by gas chromatography- tandem mass spectrometry with auto-solid phase extraction
Abstract: In this study, a method for the determination of nine N-nitrosamines in water was established by auto-solid phase extraction (ASPE)-gas chromatography-tandem mass spectrometry (GC-MS/MS). After the water samples were enriched by NDMA-SPE at a speed of 10 mL·min-1, the impurities and the water film on the surface of SPE bed were removed by leaching with 20% methanol water solution. The analytes were eluted and collected from the SPE bed with dichloromethane. After concentration, the quantitative analysis was conducted through GC-MS/MS. The analytes were separated on a Rtx-Wax chromatographic column,and ionized by electron impact (EI) source. The data were collected by multiple reaction monitoring (MRM) mode,followed by quantitative analysis using internal standard method. The correlation coefficients of linear calibration curves were over 0.999 in the corresponding linear ranges(1.00—100 μg·L-1). The method detection limit was 0.1—0.5 ng·L-1. The recovery rates of the nine N-nitrosamine compounds were 71%—94%, 74%—95% and 75%—103% at the low, medium and high spike levels, respectively. The corresponding relative deviations were 6.7%—15.8%, 5.1%—12.3% and 4.5%—9.6%, respectively.