Screening and quantification of pesticides in water using a dual-function graphitized carbon black disk

A simple platform for combining solid phase extraction (SPE) and surface-assisted laser desorption ionization mass spectrometry (SALDI-MS) of extracted analytes, using disks prepared by embedding graphitized carbon black (GCB-4) particles in a network of polytetrafluoroethylene (PTFE), is presented. The system provides a convenient approach for rapid SALDI-MS screening of substances in aqueous samples, which can be followed by robust quantitative and/or structural analyses by liquid chromatography (LC)/MS/MS of positive samples. The extraction discs are easily transferred between gaskets where the sample extraction and desorption of selected samples is performed and the mass spectrometer. The SPE and SALDI properties of the new GCB-4 disc have been characterized for 15 pesticides with varying chemical properties, and the screening strategy has been applied to the analysis of pesticides in agricultural drainage water. Atrazine and atrazine-desethyl-2-hydroxy were detected in the sampled water by SALDI-MS screening and subsequently confirmed and quantified using LC/MS/MS.