[Determination of three volatile N-nitrosamine in drinking water by solid phase extraction and gas chromatography-triple quadrupole mass spectrometry with programmable temperature vaporizer-based large volume injection].

A method had been developed for the determination of three N-nitrosamines, namely, N-nitrosodimethylamine (NDMA), N-nitrosomethylethylamine (NMEA), and N-nitrosodiethylamine (NDEA) in drinking water by solid phase extraction (SPE) and gas chromatography-triple quadrupole mass spectrometry (GC-QqQ-MS/MS) with programmable temperature vaporizer (PTV)-based large volume injection (LVI). The N-nitrosamine compounds were extracted from the water sample using a solid phase extraction (SPE) cartridge filled with coconut charcoal, and then eluted with 10 mL methylene chloride. The eluate was dried by anhydrous sodium sulfate and 10 µL was injected into the GC-MS/MS by PTV-LVI. The target compounds were detected by the multi-reaction monitoring (MRM) mode, and quantified with the external standard method. The results showed that the three compounds had good linearities in the range of 1-50 ng/L with correlation coefficients (r2) higher than 0.999. Drinking water samples were spiked with the target compounds at three concentration levels (10, 20, and 50 ng/L), and satisfactory recoveries (between 94.8% and 109%) and good reproductivities (relative standard deviation RSD<10%) were achieved. The limits of quantitation (LOQs) of the three N-nitrosamines were found to be in the range of 0.08-0.7 ng/L. The developed method was sensitive, accurate, convenient, and reliable for the determination of the three trace level N-nitrosamines in drinking water.

[Determination of 18 polychlorinated biphenyls in camellia seeds by multiple vortex and gas chromatography-triple quadrupole mass spectrometry].

A method based on the cleaning effects of different sorbents and gas chromatography-triple quadrupole mass spectrometry (GC-QQQ-MS/MS) was developed for the determination of 18 polychlorinated biphenyls (PCBs) in camellia seeds. The camellia seeds were extracted with acetonitrile, salted out with sodium chloride, then cleaned-up by QuEChERS with anhydrous MgSO4, C18, primary secondary amine (PSA), and multi walled carbon nanotubes (NANO) using multiple vortex after the centrifugal separation, and finally analyzed by GC-QQQ-MS/MS in multiple reaction monitoring mode via positive electrospray ionization. All the 18 PCBs could be completely separated with an excellent linear relationship. The limits of detection for the 18 PCBs were 5 µg/kg. For all the samples, the mean spiked recoveries was 109.2% with relative standard deviations (RSDs) of 2.9%-6.2% (n=3). The extraction, purification and analytical methods were developed and assessed. The method was successfully applied to the 48 samples from three main producing provinces of camellia seeds. All the 18 PCBs were not detected from the 48 samples.