Picogram determination of N-nitrosodimethylamine in water

N-nitrosodimethylamine (NDMA) persistence within surface waters is a major concern for downstream communities exploiting these waters as drinking water supplies. The objective of this study is to develop a novel and efficient analytical method for NDMA via different technologies: pulsed splitless gas chromatography-nitrogen phosphorus detector (GC-NPD), large volume injection (LVI) gas chromatography-mass spectrometry (GC/MS) via programmable temperature vaporizer (PTV)inlet or PTV-gas chromatography-triple quadruple mass spectrometry (GC-MS/MS) and continuous liquid liquid extraction. It was found that the sensitivity required for NDMA analysis by GC-NPD can only be achieved when the NPD bead is extremely clean. LVI via PTV can greatly improve GC-MS system sensitivity for analyzing NDMA. With the help of DB-624 (25m x 200 mu m x 1.12 mu m) connected with DB-5MS (30m x 250 mu m x 0.25 mu m) in series, PTV-GC/MS could overcome the matrix interference for the trace analysis of NDMA. Variable instrument conditions were studied in detail, with the optimized process being validated via precision and accuracy studies. PTV-triple quadruple GC-MS/MS system could efficiently remove the interference on a single DB-5MS (30m x 250mm x 0.25mm) column with good sensitivity and selectivity. The developed methods have been successfully applied to test NDMA in different types of water samples with satisfactory results.