Simultaneous determination of acid-soluble biomass-derived compounds using high performance anion exchange chromatography coupled with pulsed amperometric detection†
A high performance anion exchange chromatography-pulsed amperometric detection (HPAEC-PAD) method using a CarboPac™ PA100 column for the simultaneous determination of 25 soluble compounds originating from all polymer classes (cellulose, hemicellulose, lignin and pectin) in biomass hydrolyzates was developed and validated. The method was optimized for resolution varying the column oven temperature (in the range of 30–50 °C) and the eluents (100 mM NaOH, 200 mM NaOH, 100 mM NaOH/500 mM NaOAc and water). The optimized method used gradient elution at 40 °C and had 70 min duration for one run. The detection limits ranged between 0.14 mg L−1 for both 2,6-dimethoxyphenol and 3,5-dimethoxy-4-hydroxybenzaldehyde and 21.9 mg L−1 for 4-methoxybenzyl alcohol, linearity was always >0.99, and sensitivity ranged between 0.0023 (nC min)/(mg L−1) for glucuronic acid and 8.4 (nC min)/(mg L−1) for 3,5-dimethoxy-4-hydroxybenzaldehyde. In contrast to the established photometric lignin measurement the HPAEC-PAD method allows for a distinction between several acid-soluble lignin compounds. The method was applied to 17 different biomass hydrolyzates and displayed the capability to quantify a wide range of soluble products covering very different hydrolyzate compositions.