Organochlorine pesticides (OCPs) need to be controlled down to extremely low levels in water. From the Water Framework Directive (WFD), the aim is to have limits of detection for certain OCPs at 10 fg/l for surface and coastal water, which can present a challenge to the analyst. Traditionally large volumes of sample and extraction solvent would need to be used to achieve the high levels of enrichment required. This application note investigates instrumental parameters that may increase sensitivity and potentially enable a more automated approach. Low limits of detection for OCPs can be achieved using Negative Chemical Ionisation (NCI) with accurate mass on the Agilent 7200 GC-Q/TOF. This application further investigates the methodology to enhance sensitivity by switching reagent gas from methane to ammonia and through the use of a large volume injection method with the Cold Inlet System (CIS 4) inlet to improve detection limits. Initial results showing good signal to noise are illustrated for endosulphan, heptachlor and the pyrethoids.
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Initial GC/Q-TOF Work for Trace Analysis of Organochlorine Pesticides Using NCI