The samples were filled in 1000 mL amber glass bottles and stored for up to one week at 5°C ± 3°C in the dark until extraction. A method blank was prepared every month to account for potential contamination from sample handling using ultrapure water. Solid phase extraction (SPE) was performed using Atlantic® HLB SPE Disks from Horizon (Salem, NH, USA) with a 47mm diameter. The disks were conditioned twice for one minute using acetonitrile, and then twice for one minute using milliQ water. The samples were pumped through each disk at a flow rate of roughly 30 mL/min, using the SPE-DEX 47900 system from Horizon (Salem, NH, USA). Sample loading was followed by washing the disks twice for 1min with milli-Q ® water and drying by airflow for 15 min. The analytes were eluted for 1 min with cyclohexane, followed by an acetone elution for 1 min, then 4