Determination of the oxalate content in food by headspace gas chromatography

A novel method for the determination of oxalate content in food is developed using headspace gas chromatographic (HS-GC) technology. This method is based on the reaction between oxalate and sodium bromate in an acidic medium, in which oxalate is converted to carbon dioxide that is measured by GC with a thermal conductive detector. It was found that a complete conversion of oxalate to carbon dioxide can be achieved at a temperature of 70 C within 4 minutes. The optimal reaction conditions obtained in the present work also minimize the side reactions caused by interfering species, such as organic acid and alcohols, with sodium bromate. The present method is simple, rapid, accurate, and very suitable for use in quantification of oxalate content in food.