Triple quadrupole 7000c

Analytical determination of methyl esters of HAAs was performed using a 7890B GC connected in series to a 7000C triple quadrupole (Agilent Technologies). Ionization was carried out in the electron ionization mode. One µL of the derivatized extract was injected in splitless mode using a7638B automated injector (split flow=50 mL/min, splitless time=1.5 min). GC separation of the analytes was achieved using a capillary The analyzer was operated in selected reaction monitoring (SRM) mode, using nitrogen (1.5 mL/min) as the collision gas. A minimum of two SRM transitions was acquired per analyte (see Table 4). Figure 4 shows the total ion chromatogram obtained after the analysis of a standard calibration solution at a concentration of 10 µg/mL. Mass acquisition was performed using MSD ChemStation and data analysis was done with Mass Hunter B.08 (Agilent Technologies).

Two different analytical approaches had to be employed to cover all analytes. Medium to highly polar compounds were analyzed according to Barbieri et al. (2020) (link) Nonpolar pesticides were analyzed following a previously optimized method based on liquid-liquid extraction (LLE) and gas chromatography-tandem mass spectrometry (GC-MS/MS) detection (Peris and Eljarrat, 2020) . Water samples (50 mL) were manually extracted twice with 25 mL of EtAc/chloroform (1:1) mixture by classical LLE in a 100 mL separatory funnel. The extract obtained was evaporated under a gentle stream of nitrogen: firstly, to an approximate volume of 1 mL using a Turbovap (Biotage, Sweden), and then, to dryness using a needle evaporator (Reacti-Vap III, Pierce, USA). The dried extract was reconstituted in 50 µL of EtAc (1000x concentration factor). GC-MS/MS determination was performed using a 7890B GC system coupled to a 7000C triple quadrupole (Agilent Technologies, Santa Clara, CA, USA) detector. For chromatographic separation, a DB-5MS column (30 m x 250 μm x 0.25 μm) was used.
Table S2 in SM summarizes the analytical limits of detection (LODs) and quantification (LOQs) achieved for the target pesticides with the methodologies employed. Table S3 in SM reports the main LC-MS/MS and GC-MS/MS acquisition parameters.