2.3 | Gas Chromatography-Mass Spectrometry (GS-MS) data extraction
The dried hair extracts were resuspended in 200 μL of sodium hydroxide (1 M) and chemically derivatized via the methyl chloroformate method based on previous recommendations.17 All samples were analyzed in a single batch, and derivatized compounds were separated by a GC7890 chromatography system coupled to an MSD5975 with electron impact ionization (70 eV) (Agilent, California, USA). The automated Mass Spectral Deconvolution and Identification System software was utilized for metabolite deconvolution. Subsequently, the metabolite identifications, GS-MS data mining, and data normalization were performed as previously described.17