Determination of synthetic colours in foods using high-performance liquid chromatography

Abstract

A method is proposed for the extraction, separation, identification and quantitative measurement of synthetic organic colouring materials in a wide range of foodstuffs. The colours are extracted with a liquid anion-exchange resin, and where irreversible binding of colours to the food has occurred during processing, the colours are released by a preliminary enzyme digestion prior to extraction. They are then re-extracted from the resin phase into aqueous solution, followed by clean-up and concentration by column chromatography on polyamide. The final eluate is concentrated and examined by high-performance liquid chromatography. For liquid foods and foods soluble in water, a shortened form of the method can be used. The method gives recovery values for most colours of 80% or better, and the reproducibility is within 5%.