SPECIFIC DETERMINATION OF MALONALDEHYDE BY N-METHYL-2-PHENYLINDOLE ORTHIOBARBITURIC ACID

Reactivity of a commercially available test kit (LPO-586), based on N- methyl-2-phenylindole, toward aldehydes was characterized and compared with that of thiobarbituric acid (TBA). In hydrochloric acid, LPO-586 produced a violet pigment with malonaldehyde (MA) but not with other tested aldehydes. In methane sulfonic acid, LPO-586 produced the viole t pigment with MA and 4-hydroxynonenal (HNE), but not with other teste d aldehydes. Pigment formation with MA was not inhibited by other alde hydes, but that with HNE was inhibited by alka-2,4-dienals. TEA produc ed a red pigment with MA but not with other tested aldehydes in hydroc hloric acid or in acetate with ethylenediaminetetraacetic acid (EDTA). Both the LPO-586 test in hydrochloric acid and the TBA test in hydroc hloric acid or in acetate with EDTA can be used for specific measureme nt of MA in oxidized lipid samples.