Direct‑injection UHPLC-MS/MS multiresidue method for the determination of 97 pesticides in groundwater and surface...

A direct-injection UHPLC-MS/MS method was developed and validated for the simultaneous determination of 97 pesticides in groundwater and surface water. By bypassing time-consuming SPE and injecting samples directly, the proposed workflow achieves high-throughput performance without compromising regulatory sensitivity. Chromatographic separation was achieved within an 11 min active gradient, followed by a 6 min re-equilibration phase, resulting in a total cycle time of 17 min at 0.300 mL/min and 25 °C, while detection was performed on a triple-quadrupole mass spectrometer operating in SRM mode with rapid polarity switching. Calibration was carried out using matrix-matched calibration solutions applying a weighted (1/x) linear regression to compensate for heteroskedasticity and ensure accuracy at trace levels. The method achieved LOQs between 0.005 and 0.025 µg/L, fully meeting the requirement of LOQ ≤ 1/3 of the Italian EQS. Expanded uncertainties (k = 2) ranged from 18 to 19%, well below the 50% limit established by Legislative Decree 219/2010. Recoveries were between 87 and 98% with RSDs < 15% across all analytes and matrices. The workflow provides robust, sensitive, and regulation-compliant monitoring of pesticides in water bodies, enabling high-throughput analysis without any pre-concentration step.