GC-MS Analysis of Hair Samples

The MCF derivatized extracts were analyzed in an Agilent C7890B gas chromatograph coupled to a MSD5975 mass spectrometer. The mass spectrometer setting was at 70 eV. All hair samples were analyzed in a single batch and the gas chromatographic column used for analysis was a zb-1701 gas chromatographic capillary column constituted of 30 m × 250 μm id × 0.15 μm with a 5 m guard column (Phenomenex). GC–MS analysis parameters were based on the parameters reported in Smart et al. (2010) (22 (link)) and Han et al. (2019) (23 (link)). 1 μL of sample was injected into the inlet using an autosampler with the inlet temperature at 260°C and in the pulsed splitless mode at 180 kPa for 1 min. The helium gas flow through the GC-column was set at a constant flow of 1.0 mL/min. The GC oven temperature was maintained at 45°C for 2 min, and increased at 9°C/min to 180°C held for 5 min. The temperature gradually increased at 40°C/min to 220°C. After 5 minutes, the temperature increased at 40°C/min to 240°C for 11.5 min. Finally, the temperature was increased at 40°C/min to 280°C, and maintained at 280°C for 2 min. The temperature of the interface was kept at 250°C, and the quadrupole temperature was kept at 230°C. The mass spectrum started after 5.5 min with a mass range of 38-550amu, and the scanning time was 0.1 s.