Evaluation of fourier transform infrared spectroscopy measurements of glucose and xylose in biomass hydrolyzate

Measurement of sugars using traditional spectroscopic (UV/Vis) assays or high performance liquid chromatography (HPLC) can be time consuming and expensive. Alternative methods for measuring sugars after enzymatic hydrolysis of biomass would be convenient for screening potential biomass feedstocks and pretreatment methods. Fourier transform infrared spectroscopy (FTIR) has been utilized for measuring composition of various aqueous solutions and is evaluated here as an alternative to UV/ Vis and HPLC assays. Solutions of glucose and xylose with concentrations between 0 and 1.5% w/v (total sugar content between 0 and 3.0% w/v) were used to build calibration curves for all three methods. A validation set of 10 samples of varying concentrations of glucose and xylose (between 0 and 1.5% w/v) were used to quantify the performance of the three measurement techniques. The FTIR assay was able to predict the glucose and xylose concentration with a standard error of prediction (SEP) of 0.03% (w/v), lower than the SEP for the HPLC (∼0.06%) and UV/Vis (∼0.07%) assays. The FTIR assay was also able to accurately measure the sugar concentration of wheat stover (raw and pretreated with sodium hydroxide) after enzyme hydrolysis, although all three techniques produced similar results.