Assessment of LC-QTOF-MS data independent acquisition for quantification and suspect screening of pesticides in agriculture impacted water samples

Assessing the impact of agricultural pesticides, and their potential transformation products, in surface (SW) and groundwater (GW) requires the application of target and screening methodologies to cover the maximum number of species. This research investigates the performance of the data independent acquisition (DIA) mode for the quantification of target compounds and the suspect screening of additional pesticides in SW and GW based on a single chromatographic run. Samples were analysed using a liquid chromatography quadrupole timeof-flight mass spectrometry (LC-QTOF-MS) platform, combined with an on-line solid-phase extraction (SPE) step. A suite of fungicides and insecticides, widely employed in intensive viticulture areas, was selected to assess the performance of target and screening methodologies in combination with a database of product ion spectra for more than 700 pesticides. As regards quantification of targets, the method achieved limits of quantification (LOQs) between 2 ng l-1 and 25 ng l-1, with linear responses from LOQs up to 500 ng l-1. Accuracy remained between 70 % and 120 %, based on the use of ultrapure water calibration standards. Suspect screening permitted the identification of 90 % of tested compounds when added to SW and GW at levels above 50 ng l-1, improving the percentage of correct identifications versus those attained operating the LC-QTOF-MS platform in the data dependent acquisition (DDA) mode.