Chemstation for gc ms

GC–MS analysis was performed on an Agilent 7693/5975 GC–MS autosampler system (Agilent, Manchester, UK). The sample was injected onto a HP-5MS 15 m non-polar column DB-5MS (J and W scientific, Santa Clara, CA, USA) (0.25-μm film thickness, 0.25 mm I.D.). The injection temperature was 250 °C in split mode (1:20). The oven temperature was programmed from 40 to 320 °C at a rate of 5 °C/min until 250 °C. The carrier gas was helium, with flow rate of 1.1 mL/min and pressure of 7.1 psi. Mass spectra were obtained by electron ionization at 70 eV, and mass scan from 35 to 500 amu. A total of 1 μL of the sample was injected, and compounds were separated during a 42 min run. Compounds were identified using the National Institute of Standards and Technology (NIST) library and literature ion data (Table 3; see Figure S3 for GC-MS chromatograms) and quantified based on an external standard calibration curve. Five concentrations (0.15–0.5 mg/mL) of sulforaphane standard (Sigma Aldrich, Dorset, UK) were prepared in DCM (r² = 0.99). Data analysis was performed using ChemStation for GC-MS (Agilent, Manchester, UK).

All glassware was prepared as described elsewhere (15 (link)). The internal standard 2-methylnaphthalene (Acros Organics) (10 mg) dissolved in 1 ml of methanol (HPLC grade) was used (final concentration, 2 mg liter⁻¹). All filters, along with the supernatants, were included in the solvent extractions to determine any residual PAH. Each PAH was extracted three times as described previously (15 (link)) (Fisher Scientific) using ethyl acetate (Fisher Scientific). Samples were resuspended in 1 ml of dichloromethane (HPLC grade; Acros Organics) and separated by gas chromatography-mass spectrometry (GC-MS) using an Agilent 7890 GC interfaced with an Agilent 5975C MS. Samples were injected with a 1-μl splitless injection (injector temperature, 250°C) onto an Rtx-1MS column (30 m by 250 μm by 0.25 μm) using helium as the carrier gas at a constant flow of 1 ml min⁻¹. Oven temperatures were programmed with an initial increase from 40°C to 300°C at 10°C min⁻¹ and a final hold at 300°C for 10 min. The transfer line was held at 230°C onto a source for the MS, which was in full-scan mode (scan range, 50 to 650 Da). Data were analyzed and integrated using ChemStation for GC-MS (Agilent), and the mass spectra of putative metabolites were identified by library comparison.

The major hydrolysis products produced by Eruca leaves, sativin and erucin, were investigated and extracted according to the protocol of Bell et al. (2020) (link). GC–MS was performed on an Agilent 7693/5975 GC–MS with autosampler (Agilent, Manchester, UK). 1 μL of each sample was injected into VF-5ht 15 m column (0.1 μm film thickness, 0.25 mm I.D.; Agilent). Injection temperature was 250°C in split mode (1:20); oven temperature was programmed from to 40°C at a rate of 5°C/min until 320°C. Carrier gas was helium, with a flow rate of 1.1 mL/min and a pressure of 1.4 psi. Mass spectra were obtained by electron ionization at 70 eV, and mass scan from 35 to 500 amu. Compounds were identified using literature ion data and quantified based on integrated peak areas of an external standard calibration curve of AITC (Sigma). Five concentrations of AITC were prepared from a stock of in dichloromethane (DCM), ranging from 0 to 10 μM (r² = 0.999; y = 1E+06). Data analysis was performed using ChemStation for GC–MS (Agilent). Data are expressed in nmol g^-1 dry weight.