Simultaneous densitometric determination of eight food colors and four sweeteners in candies, jellies, beverages and pharmaceuticals by normal-phase high performance thin-layer chromatography using a single elution protocol

The present work describes a novel application of high performance thin-layer chromatography for the separation and quantification of eight food colors (amaranth, allura red, erythrosine, fast green, indigo carmine, quinoline yellow, sunset yellow and tartrazine) and four intense sweeteners (acesulfame, aspartame, saccharin and neohesperidin) using a single mobile phase. The analyte zones were detected densitometrically at 210, 295, 450 and 550 nm. The best chromatographic performance for all the additives was achieved using acetonitrile: water: ethyl acetate: 10% aqueous ammonia (9:1:1:1, v/v/v/v) as the solvent system within 20 min. The developed method was validated as per International Conference on Harmonization (ICH) guidelines for linearity, sensitivity, selectivity, accuracy (recovery), precision (repeatability and reproducibility), robustness and stability. The limit of detection and limit of quantitation ranged from 0.2 to 9.8 ng/zone and 0.7-29.7 ng/zone respectively and the correlation coefficient ( r2) values for the calibration curves were ≥ 0.9973 for all the additives. The developed method was successfully applied to determine food colors and sweeteners in candies, jellies, beverages and pharmaceuticals with minimal sample processing. The recovery of different additives obtained from food products, beverages and pharmaceuticals ranged from 96.6 to 106.7 %. The results showed that all the samples contained food additives within the permissible limits. The developed method is simple, precise, accurate and economical for routine quality control of foodstuffs.