Each fermentation flask was extracted with 30 mL of ethyl acetate for 1 h, shaking gently at 150 rpm. A 12 mL aliquot of the organic phase was then removed and liquid partitioned with an equivalent volume of deionized H2O. From the organic phase, a 5 mL aliquot was then transferred into pre-weighed glass vials and then dried under a stream of air or nitrogen.
Based on determined extract weights, samples were resuspended in methanol to yield a final concentration of 500 µg/mL. Prior to UPLC-HRMS analysis, an aliquot of internal standard (dioctyl phthalate) was added to each sample to be used as a quality control for data preprocessing. UPLC-HRMS analysis was carried out using a Kinetex 1.7 µm C18 column (Phenomenex, 50 × 2.1 mm) and an Accela Thermo UPLC with a Thermo Exactive mass spectrometer (ThermoFisher Scientific, Waltham, MA, USA) in ESI+ mode (with a m/z 190–2000 mass range).
Based on determined extract weights, samples were resuspended in methanol to yield a final concentration of 500 µg/mL. Prior to UPLC-HRMS analysis, an aliquot of internal standard (dioctyl phthalate) was added to each sample to be used as a quality control for data preprocessing. UPLC-HRMS analysis was carried out using a Kinetex 1.7 µm C18 column (Phenomenex, 50 × 2.1 mm) and an Accela Thermo UPLC with a Thermo Exactive mass spectrometer (ThermoFisher Scientific, Waltham, MA, USA) in ESI+ mode (with a m/z 190–2000 mass range).