determination of total acid content in vinegars by reaction-based headspace gas chromatography

This work reports on a simple and efficient method for the determination of total acid content in vinegars by reaction-based headspace gas chromatography. the method is based on the neutralization reaction between the acids in vinegar and carbonate solution in a closed headspace sample vial, from which the carbon dioxide generated from the reaction is analyzed by gas chromatograph equipped with a thermal conductivity detector. the results showed that the headspace equilibration of co2 generated from the reaction was achieved in 15 min at 60 °c. the method has a good precision and accuracy, in which the relative standard deviation in the repeatability measurement was 1.73 %, and the relative differences between the data obtained by the headspace gas chromatographic method and the reference titration method were within 4.81 %. the present method is particularly suitable to be used for determining the total acid content of vinegar not only in the process control but also the quality check of point-of-sale samples from commercial markets.