Determination of organophosphorus pesticides in water by solid-phase extraction followed by liquid chromatography/high-flow pneumatically assisted electrospray mass spectrometry

Priority organophosphorus pesticides in water samples were subjected to analysis by solid-phase extraction followed by liquid chromatography/high-flow pneumatically assisted electrospray mass spectrometry (LC/ESP-MS). The operational parameters of ESP optimized by use of an eluent flow rate of 0.3 mL/min and at a source temperature of 150 [degrees] C were as follows: drying gas flow rate, 250-300 L/h; ESP nebulizing gas flow, 5-20 L/h; ESP voltage, 2-3.5 kV; HV lens voltage, 0.2-1.0 kV; extraction voltage, 20-130 V; focus voltage, and the ion energy. Water samples (500 mL) were preconcentrated by use of either Empore disks of [C.sub.18] and styrene-divinylbenzene or monofunctional [C.sub.18] cartridges in an ASPEC XL system. No thermal degradation was observed for the organophosphorus pesticide triclorfon, which usually causes a problem under LC/MS using thermospray interface. The method detection limit was 0.01 [[micro]gram]/L for most of the organophosphorus pesticides used employing SIM of the [M + Na]+ ion.