KINETIC-FLUOROMETRIC DETERMINATION OF MALONALDEHYDE BASED ON THE HANTZSCH REACTION - APPLICATION TO OLIVE OIL ANALYSIS

A kinetic study was completed on the formation of 1,4-disubstituted-1, 4-dihydropyridine-3,5- dicarbaldehyde from malonaldehyde and methylami ne, via the Hanztsch reaction. The influence of n-hexylaldehyde and ac etaldehyde in the reaction has been studied, and it has been concluded that the presence of the aldehydes is not necessary for the reaction. The fluorescence emission of the reaction product was monitored at 47 0 nm with excitation at 405 nm, and the effect of instrumental and exp erimental variables on the reaction was investigated. A pH of 4.0, obt ained by a 0.25 M sodium acetate-acetic acid buffer solution, a 10 mM methylamine concentration, a 30% (v/v) 2-propanol content, and a tempe rature of 75 degrees C were selected for the reaction. A kinetic-fluor ometric method to determine malonaldehyde has been proposed, for malon aldehyde concentrations ranging from 0.5 to 2.8 mu g mL(-1), and a wid e study of the possible interferences in the reaction has been perform ed. The kinetic-fluorometric method was applied to olive oil samples.