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.