Determination of synthetic dyes in selected foodstuffs by high performance liquid chromatography with UV-DAD detection

A relatively fast method was developed and applied to the determination of selected synthetic food dyes (Sunset Yellow, Tartrazine, Amaranth, Brilliant Blue and Red-40) in three different kinds of foodstuffs: solid juice powders, solid jelly powders and soft drinks. High performance liquid chromatography with UV-DAD detection was employed. The developed chromatographic method employed an ODS Zorbax column (250 mm; 4.6 mm; 5 μm). Two different solvent systems were employed depending on the expected dyes in the studied samples. Sample preparation consisted of dissolving and filtering the samples and showed high throughput. Adequate detection and quantification limits together with high recoveries (better than 98.8%) were obtained. All studied samples showed dye levels in conformity with Brazilian legislation. Indeed some products showed poor quality and/or production controls due to the variability between lots. This fact was more critical for Tartrazine and Sunset Yellow in solid juice powders and there is concern that these substances can exceed legislated values. It was also observed that different producers use different dyes and/or composition in similar products.