Trace determination of triazine herbicides by means of coupled-column liquid chromatography and large volume injection

Coupled-column liquid chromatography (LC-LC) with ultraviolet detection was used for the trace-level determination of simazine, atrazine, terbuthylazine and terbutryn in environmental water samples. A sample volume of 2 mi was directly injected in the chromatographic system, using two reversed-phase C-18 coupled columns. The mobile phases consisted of two mixtures CH3CN/H2O, one with 40% of acetonitrile (M-1) and one with 70% (M-2). As a result, a rapid procedure with detection Limits down to 0.1 mu g l(-1) was developed. The method was validated by means of recovery experiments. Drinking and surface water samples were spiked at 4 and 0.4 mu g l(-1) yielding average recoveries between 86-104% (n=5) with coefficients of variation between 1-6%. The overall procedure allowed a sample throughput of up to 60 samples per day. Surface water samples from a wet area of Castellon (Spain) were analyzed by means of the proposed LC-LC procedure, thus simazine, terbuthylazine and terbutryn were detected at sub-mu g l(-1) levels. Lower detection limits, between 0.02-0.05 mu g l(-1) were reached by preconcentration of 100 mi of water samples on C-18 bonded phase solid phase extraction (SPE) cartridges. Drinking water samples spiked at 0.1 mu g l(-1) were preconcentrated and analyzed by LC-LC yielding average recoveries between 84-103% (n=3) with coefficients of variation between 2-5%.