Simultaneous determination of synthetic colorants in yogurt by HPLC

This article reports on a method to determine synthetic dyes in yogurts and milk drinks. Initially a method for extraction of artificial dyes was developed to pretreat samples in order to extract most of the artificial colorants. Then, the colorants were analyzed by HPLC-PAD using gradient elutions. The method was linear in the range of 0.5-25 mg L−1 colorants (0.9991 < R2 < 0.9998), with LOD of 0.18-4.58 μg L−1. The results recovery test on two levels ranged from 82% to 115%. The reference solution of the analytes remained stable for 3 months. In the yogurt samples analyzed, the dye E122 (1.4-11.75 mg L−1) was found in most samples, followed by dye E123 (3.12 and 12.56 mg L−1). All samples had concentrations below the maximum level allowed for use in yogurt (100 mg/100 g dyes).