FISH ROE SAMPLE PREPARATION FOR SYNTHETIC FOOD DYES DETERMINATION BY HPTLC

Abstract

Food dyes are widely used in food products to offset the colour loss. To prevent fraud in the food industry, to ensure food safety and consumer health protection, it is necessary to implement fast, accurate and reliable methods for the analysis of dyes. A relatively fast method based on high-performance thin-layer chromatography (HPTLC) - photodensitometry was developed and applied to determine two synthetic food dyes (Sunset Yellow – E 110 and Ponceau 4R – E 124) in fish roe. TLC separation was carried out on silica gel plates, using the mixture isopropyl alcohol-ammonia (2:1, V/V) as mobile phase. Good separation of the dyes was achieved, the Rf values being 0.39 for E110 and 0.12 for E124, respectively. Due to the complexity of the matrix, sample preparation was performed into two steps: (i) extraction by ultrasound-assisted extraction with methanol-ammonia (1:1, V/V) and (ii) purification of the extract by ion-pair solid phase extraction (IP-SPE) on ChromaBond RP-18E cartridges. For both dyes, the overall recovery for the sample preparation step was higher than 91%, the relative standard deviation being less than 3.5%. The procedure was applied for E110 and E124 determination from a “red caviar” sample with the declared content of dyes.