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Solid phase extraction, based on the use of color catcher sheets, was successfully employed for the preconcentration of food dyes from alcohol containing beverages. The photos of color catcher sheets with the adsorbed dyes were taken with a mobile phone. The smartphone-based image analysis of the photos was performed using Color Picker application. The values of several color spaces were collected. Specific values from RGB, CMY, RYB and LAB color spaces were proportional to the dye concentration in the analyzed samples. The described inexpensive, simple and elution free assay enables analysis of dyes concentration in various solutions. [Display omitted] • Synthetic food dyes in alcohol containing beverages were extracted. • Color catcher sheets were used as low-cost textile-like adsorbent. • Smartphone-based image analysis enabled semiquantitative determination of dye concentration. [ABSTRACT FROM AUTHOR]

Abstract: The present work proposes a study of the synthesis of poly(N-isopropylacrylamide-co-N,N′-methylene bisacrylamide) monolithic column embedded with γ-alumina nanoparticles and its applications to the extraction of synthetic food dyes in soft drink samples. The monolithic column was synthesized inside fused silica capillaries using thermally initiated free-radical polymerization with N-isopropylacrylamide (NIPAAm) as the monomer, N,N′-methylene bisacrylamide (MBAAm) as the cross-linker, dimethylsulfoxide (DMSO) and dodecanol as the porogen. γ-Alumina nanoparticles were introduced to prevent the swelling of the organic polymer and enhance the loading capacity. In order to obtain optimum experimental conditions, sample pH, sample flow rate, sample volume, eluent flow rate were investigated. Under the optimum conditions, we obtained acceptable linearities, low limits of detection, and good intra-day/inter-day relative standard deviations. When applied to the determination of four synthetic food dyes (Tartrazine, Sunset Yellow, Allura Red, and Azorubine) in soft drink samples, satisfactory recoveries were obtained in the range of 90.4–109.2%. [Copyright &y& Elsevier]

Abstract: The purpose of this work was to present a chromatographic methods to analyse synthetic food dyes. The following techniques has been described: thin-layer liquid chromatography (TLC), high performance thin-layer chromatography (HPTLC), traditional column chromatography, high performance liquid chromatography (HPLC), include: ion-pair chromatography (HPLC IP), reversed phase chromatography (RP HPLC) and high performance ion chromatography. [Copyright &y& Elsevier]