Assaying α-Dicarbonyl Compounds in Wine: A Complementary GC–MS, HPLC, and Visible Spectrophotometric Analysis

Abstract

We used a facile, aqueous reaction coupled with gas chromatography–mass spectrometry (GC–MS), visible spectrophotometry, and high performance liquid chromatography (HPLC) to quantify the amounts of α-dicarbonyl compounds in wine samples. The aqueous reaction between an α-dicarbonyl compound and o-phenylenediamine yields a highly stable quinoxaline molecule with an absorbance maximum of 315 nm. GC–MS is used to identify each quinoxaline via mass. Likewise, owing to the similar absorption properties of the quinoxaline products, visible spectrometry is not useful for quantitation although it reveals the absorbance maximum to use for optical detection of the quinoxalines by HPLC. The analytical techniques used in this experiment complement each other since visible spectrophotometry is needed to determine the absorption wavelength, which is used for HPLC analysis; and HPLC is used for quantitation, while GC–MS is used to confirm the identities of the reaction products.