Simultaneous Analysis of Carbamate and Organophosphorus Pesticides in Water by Single-Drop Microextraction Coupled with GC-MS

Single-drop microextraction (SDME) has been coupled with gas chromatography-mass spectrometry to enable rapid and simple simultaneous analysis of carbamate and organophosphorus pesticides (OPP). The significant conditions affecting SDME performance (microextraction solvent, extraction time, solvent volume, sample pH, stirring speed, and ionic strength) were studied and optimized. Extraction was achieved by suspending a 1.5-mu L drop of toluene from the tip of a microsyringe directly immersed in 5-mL aqueous donor solution at pH 5 stirred at 800 rpm. The dynamic linear range and detection limits of the method were evaluated by analysis of water samples spiked with carbamate pesticides and OPP. Under selected ion-storage mode, very low detection limits (0.02-0.50 ng mL(-1)) and good linearity (0.5-200 ng mL(-1)) were achieved. When SDME was applied to analysis of pesticides in natural water samples good recoveries (89.4-102.1%) were obtained. Inter-day and intra-day RSD of most results were below 5.4 and 6.1%, respectively. The method proved to be a rapid and simple tool for extraction and analysis of these pesticides in water samples.