Gc7890 system

The derivatized samples were analyzed using an Agilent GC7890 system linked to a MSD5975 with electron impact ionization (70 eV). The gas capillary column was a ZB-1701 (30 m × 250 μm id × 0.15 μm with 5 m guard column, Phenomenex). The parameters of the GC oven and MS were operated in accordance with Smart et al.^{20 (link)}’s published protocol. The samples were injected into a pulsed splitless mode inlet at 290 °C with the flow of helium gas at 1 mL.min⁻¹. The temperatures of the auxiliary, MS quadrupole, and MS source were 250 °C, 230 °C, and 150 °C respectively. The mass range was detected from 30 um to 550 µm. Scan speed was set to 1.562 µ.s⁻¹ and the solvent delay was applied until 5.5 min. The estimated time required for sample preparation, derivatisation, and GC-MS acquisition is shown in Supplementary Table S6.

The MCF derivatives were analysed in an Agilent GC7890 system coupled to a MSD5975 mass selective detector (EI) operating at 70 eV. The gas column used for all analyses was a ZB-1701 GC capillary column (30 m ⨯ 250 μm id ⨯ 0.15 μm with 5 m guard column, Phenomenex). The analysis parameters were set according to Smart et al.^{26 (link)}. Samples were injected under pulsed splitless mode with the injector temperature at 290 °C. The helium gas flow through the GC-column was set at 1 mL min⁻¹. The interface temperature was set to 250 °C and the quadrupole temperature was 200 °C. The mass spectrometry was operated in scan mode and started after 5.5 min with the mass range between 38 and 550 atomic mass units (amu) at 2.85 scans s⁻¹.

Derivatized samples were analyzed on an Agilent GC7890 system coupled with electron impact ionization (70 eV). In brief, chromatographic separation was achieved using a ZB-1701 gas capillary column (30 m × 250 μm id × 0.15 μm with 5 m guard column, Phenomenex), with a constant helium gas flow of 1 mL/min. The parameters of the GC settings and MS were in accordance with Han et al. [23 (link)]. The temperature of the inlet, the auxiliary, MS quadrupole, and MS source were 290 °C, 250 °C, 230 °C, and 150 °C, respectively. The mass range was set from 30 µm to 550 µm. Scan speed was set at 1.562 µ.s⁻¹, and the solvent delay was set to 5.5 min.