Differential pulse polarographic determination of alpha-dicarbonyl compounds in foodstuffs after derivatization with o-phenylenediamine

A differential pulse polarographic method has been developed for the indire ct determination of diacetyl and other vicinal diketones in foodstuffs, bas ed on the quantitative derivatization of the diketones with o-phenylenediam ine to give quinoxalines. The method allows the identification of diacetyl and methylglyoxal in brandy, vinegar, wine, and butter samples. The polarog raphic reduction peaks of the quinoxalines formed are sufficiently separate , in some cases, to allow the simultaneous determination of these two compo unds. The polarographic method is not affected by the presence of sulfite i on, probably because the o-phenylenediamine is capable of dislodging the cl -diketones from their sulfite complexes.