Rapid method for determination of carbonyl groups in lignin compounds by headspace gas chromatography

•A GC method was developed to detect carbonyl groups in lignin compounds.•The reaction for determination of aldehydes can be completed at room temp. within 3 min and ketones at 80 °C within 30 min.•The presented method is simple and accurate for carbonyl quantification.

The paper reports on a novel method for rapid determination of carbonyl in lignins by headspace gas chromatography (HS-GC). The method involves the quantitative carbonyl reduction for aldehydes in 2 min at room temperature or for acetones in 30 min at 80 °C by sodium borohydride solution in a closed headspace sample vial. After the reaction, the solution was acidified by injecting sulfuric acid solution and the hydrogen released to the headspace was determined by GC using thermal-conductivity detector. The results showed that with the addition of SiO2 powder, the reduction reaction of carbonyl groups can be greatly facilitated. The method has a good measurement precision (RSD < 7.74%) and accuracy (relative error <10% compared with a reference method) in the carbonyl quantification. It is suitable to be used for rapid determination of carbonyl content in lignin and related materials.