Determination of cellulose derived 5-hydroxymethyl-2-furfural content in lignocellulosic biomass hydrolysate by headspace gas chromatography

This paper reports a robust method for rapid determination of cellulose derived 5-hydroxymethyl-2-furfural (5-HMF) in biomass hydrolysate suspension based on headspace gas chromatography (HS-GC). The headspace equilibration at 150 °C for longer than 4 min with a pH range of 2.0–3.5 and a 50% (v/v) of ethanol content can obtain the full evaporation of 5-HMF, and eliminate the formation of additional 5-HMF generation from hexose. The linear GC response of 5-HMF was achieved by controlling the sample size within 20 μL. The results showed that this method has a good precision (relative standard deviation < 6.97%) and accuracy (recoveries ranged from 94.0 to 104.8%). The limit of quantification of the method was 51 mg/L. It was also found that a considerable amount of furfural (13.8%) and 5-HMF (18.7%) was adsorbed on condensed lignin and humins in residual biomass, and the washing procedure with ethanol can completely extract the adsorbed furfural and 5-HMF. The present method is accurate, simple, and robust, it will be a powerful tool for determining the content of 5-HMF in the liquid samples from biorefinery related processes.