SEPARATION AND DETERMINATION OF DYES BY ION-PAIR CHROMATOGRAPHY

A reverse phase ion-pair high performance liquid chromatographic metho d is presented to determine six food dyes (E-110, E-120, E-122, E-123, E-124 and E-127). The tetrabutylammonium ion (TEA) is used as counter -ion in the mobile phase. The separation was accomplished with a Nova- pack C-18 column using methanol -NaH2PO4/Na2HPO4 pH=7 buffer solution 0.1M containing TBA 0.05 M as mobile phase. The chromatograms were mon otorized by measuring the absorbance at 520 nm. The influence of metha nol content, counter ion concentration, pH and now-rate of the mobile phase were investigated. In the chromatographic conditions selected, t he total chromatogram was obtained in seven minutes. The calibration g raphs were established by measuring the peak area in the chromatograms . Determination limits ranging from 1 to 7.8 ng were obtained. Samples containing the six dyes in different proportions were analyzed throug h the proposed method, obtaining good recoveries in all cases. Finally , the method was successfully applied to the analysis of dyes in sever al commercial products.