KINETIC FLUOROMETRIC-DETERMINATION OF GLIADINS IN FOODS

Kinetic methodology was applied for the first time to the determinatio n of gliadin proteins by using a stopped-flow mixing technique, The me thod is based on two simultaneous processes: the reaction between glia dins and sodium dodecyl sulfate and the elimination of the quenching c aused by this surfactant of the fluorescence of Cresyl Violet, Thus, t he increase in fluorescence intensity with time is directly related to gliadin concentration, The use of this oxazine dye allows dynamic flu orescence measurements at long wavelengths, which avoids potential int erferences from the sample matrix, The reaction rate is measured withi n 5 s, so the method is very suitable for the routine determination of gliadins in food samples, The dynamic range of the calibration graph was 0.5-50 mu g ml(-1) and the LOD was 0.25 mu g ml(-1). The RSD was 1 .6%, The method was applied to different food samples and the analytic al recoveries were 88-107%.