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 (25 m x 200 microm x 1.12 microm) connected with DB-5MS (30 m x 250 microm x 0.25 microm) 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 (30 m x 250 microm x 0.25 microm) 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.
Hu
Ruikang
R
Centre for Advanced Water Technology, Singapore Utilities International, The Toh Tuck Complex, 80/82 Toh Guan Road East, Singapore, Republic of Singapore. rkhu@cawt.sui.com.sg
Zhang
Lifeng
L
Yang
Zhaoguang
Z
D002849:Chromatography, Gas / Q000295:instrumentation / Q000379:methods; D004128:Dimethylnitrosamine / Q000032:analysis*; D004867:Equipment Design; D008401:Gas Chromatography-Mass Spectrometry; D011312:Pressure; D012680:Sensitivity and Specificity; D013594:Syringes; D013696:Temperature; D013816:Thermodynamics; D014867:Water / Q000032:analysis*
D014867:Water; D004128:Dimethylnitrosamine