Determination of 48 pesticides in water by using DI-SPME coupled to GC/MS

Abstract

This paper discusses the optimization and validation of a complete and simple method for the simultaneous determination of 48 pesticides in water by combining direct immersion solid-phase micro-extraction (DI-SPME) and gas chromatography- ion trap tandem mass spectrometry (GC-ITMS/MS). For the extraction, the different SPME parameters were tested and optimized. As a result, the polyacrilate fiber (PA 85µm) was selected in direct immersion mode; the extraction temperature was set to 60ºC with an extraction time of 45 min and a stirring speed of 250 rpm; the thermal desorption time of the fiber in the injector port was fixed to 10 min, at 275ºC. Concerning the analysis, MS/MS parameters were optimized and figures of merit were compared. Later, the method was validated and showed good linearity in the concentration ranging from 0.05 to 100 ng mL-1. The reproducibility of measurements expressed as relative standard deviation (% RSD) was found to be satisfactory. Furthermore, the detection limits obtained were in the low or sub ppt levels. Finally, the proposed DI-SPME-GCITMS/MS method was tested successfully for water samples collected along the watershed of Abou Ali River (North Lebanon).