Simultaneous determination of pesticides in river water by LC/electrosprayionization MS

An analytical method for the determination of twelve pesticides in river wa ter with liquid chromatography/mass spectrometry (LC/MS) has been developed . Under reversed-phase liquid-chromatographic conditions, twelve pesticides were analyzed using electrospray ionization(ESI) with a simultaneous acqui sition of positive ions and negative ions. The effects of the liquid-chroma tographic mobile phase on the separation of pesticides, the fragmentor volt age and the capillary voltage with ESI oil the sensitivity of pesticides we re examined. The maximum sensitivities for all pesticides in simultaneous a cquisition were accomplished by setting the capillary voltage at 2500 V. La rge volumes of river-water samples were directly injected into the precolum n, and then twelve pesticides were separated by an analytical column with a column-switching technique. The limit of detection (LOD) of these pesticid es ranged from 0.7 to 2.1 pg/ml. The overall recoveries of pesticides were from 83.4 to 109.4% (RSD(n = 5) were from 1.1 to 7.2%) for drinking water.