KINETIC DETERMINATION OF CARMINIC ACID BY ITS INHIBITION OF LANTHANIDE SENSITIZED LUMINESCENCE

The stopped-flow mixing technique was used to develop a simple and fas t kinetic method for the determination of carminic acid based on its i nhibitory effect on the fluorescence intensity of the europium(III)-di phacinone-ammonia system in the presence of Triton X-100. Analytical d ata can be obtained within 10 s after the reactants are mixed, which m inimizes manipulation and enables the ready application of the propose d method to routine analyses for carminic acid in orange soft drinks. The dynamic range of the calibration graph was 0.5-15 mu g ml(-1) and the relative standard deviation less than 4%. The analytical recoverie s obtained by applying the method directly to the analysis of samples ranged from 90.0 to 111.8%.