6520 accurate mass q tof lc ms apparatus

Alginate beads (2% w/v) with or without PAA (1% w/v) were prepared as previously described and washed with double‐distilled H₂O. Batches containing 90–150 beads of each matrix type were selected, bead diameter was measured, and total bead volume was calculated (ca. 1.7–3.1 ml per batch). Next, each batch was incubated in a 5 ml DNT (5 mg l⁻¹) solution for 3 h at 30°C. The medium was filtered (0.45 μm syringe filter) and stored at −20°C until analysed. The beads were lightly dried from excess liquid, transferred to methanol (3 ml) and shaken at 30°C for 3 h. The methanol extract was filtered (0.45 μm syringe filter) and stored at −20°C until analysed. DNT concentrations in the medium and bead extracts were determined by liquid chromatography/mass spectrometry (LC/MS) using an Agilent 1200 system composed of a ZORBAX Eclipse XDB‐C18 (2.1 mm × 50 mm) column and an Agilent 6520 Accurate‐Mass Q‐TOF LC/MS apparatus, equipped with an electrospray ionization source (ESI) and a UV detector (Agilent Technologies, Santa Clara, CA, USA) as previously described (Shemer et al., 2018). Two sets of calibrants were used to quantify DNT in the media surrounding the beads and the bead extract, containing DNT dissolved in H₂O or methanol, respectively.