Simultaneous determination of a wide spectrum of pesticides in water by means of fast on-line SPE-HPLC-MS-MS - a novel approach

A new system has been developed for rapid on-line SPE-LC-MS-MS analysis of a wide spectrum of trace level pesticides in drinking and surface water The system employs a serial arrangement of two different turbulent flow columns (TFC; polymer based column in front, carbon based column back) for rapid extraction (Turbulent flow solid phase extraction; TFSPE) from small sample volumes (10 mL) at high flow rates (5 mL min(-1)). Purely organic eluent is used for TFC elution, and the effluent is re-mixed with water in a mixing chamber in front of the HPLC column to provide efficient analyte focusing. This methodology allows to use a short monolithic LC column for the following fast on-line LC-APCI-MS-MS analysis. This approach gives quantitative results for nearly 30 pesticide species (triazines, phenyl ureas, organophosphorous pesticides and others) in less than 14 min and, thus, allows considerably increased sample throughput. The method is well reproducible, robust and extremely sensitive achieving detection limits between 0.1 and 1 ng L-1. As the comparison of internal and external calibration methods showed, potential matrix effects on the quality of the results are managed by the method in a very effective manner. Real pesticide concentrations determined in drinking water and surface water samples showed significant temporal variations but were constantly below the concentration limit for individual pollutants of 100 ng L-1.