This test method uses static headspace gas chromatography with flame ionization detection (GC–FID) to measure fusel alcohols—higher-chain alcohols produced during fermentation. The measurement of fusel alcohols is important for quality control, regulatory compliance, and detecting potential adulteration or off-spec fermentation. This test method identifies isopropanol, N-propanol, isobutanol, isoamyl alcohol, and N-amyl alcohol.