Determination of colorant matters mixtures in foods by solid-phase spectrophotometry

A new, simple, sensitive and inexpensive method for simultaneous determination of Sunset Yellow FCF (SY), Quinoline Yellow and their respective unsulphonated products (Sudan I (SUD) and Quinoline Yellow Spirit Soluble (QYSS)) in mixtures is proposed. Sunset Yellow and Quinoline Yellow were selectively fixed in Sephadex DEAE A-25 gel (pH 5.0) and SUD and QYSS were selectively fixed in C-18 silica gel (pH 5.0) and the absorbances of both systems were measured directly in solid-phase. The applicable concentration ranges were from 3.0 to 500.0 ng ml(-1) for Quinoline Yellow Water Soluble (QYWS), from 3.0 to 200.0 ng ml(-1) for QYSS, from 15.0 to 500.0 ng ml(-1) for SY and from 20.0 to 200.0 ng ml(-1) for SUD. The method was applied to the determination of these compounds in soft drinks, fruit liqueurs and ice creams.