solid-phase extraction

chlorinated drinking water

drying sorbent

N-nitrosamines

silica gel moisture removal trap

Toxic substances

Chromatographic

Pollution

Water monitoring

Organic pollutants

The aim of this study was to develop a method for efficiently extracting eight N-nitrosamines (NAs) from chlorinated drinking water using a solid-phase extraction sorbent. This was achieved by completely drying the sorbent using dry air after passing the water through it and before eluting NAs from it. A 500 mL water sample containing NAs was passed through 2.0 g of Carboxen 572. The sorbent was dried by applying a vacuum (-34 kPa) to the sorbent cartridge for 1 h with a silica gel trap connected to the other end of the cartridge. The NAs were then eluted by passing 15 mL of dichloromethane through the cartridge. The dansyl derivatives of the NAs were analyzed by high-performance liquid chromatography with fluorescence detection using a Microsorb-MV Si column and a mixture of water (40%) and acetonitrile (60%) as stationary and mobile phases, respectively. The coefficients of determination (R²) for five-point linear calibration curves (2-80 ng/L) were 0.9968-0.9997. The relative standard deviations of repeated measurements were mostly less than 5.1%, but were higher for two NAs. The recoveries of all of the NAs when spiked samples were analyzed were > 95.1%, and the estimated method detection limits were 0.5-1.4 ng/L. The method showed much better performance than when the moisture trap was not applied to the cartridge, particularly when the laboratory air had a high level of humidity.