Square wave adsorptive voltammetric determination of sunset yellow

Square wave adsorptive stripping voltammetry was used for determining trace amounts of dye Sunset Yellow (E-110) for the first time. Its adsorptive voltammetric behaviour followed by a square wave mode step was investigated at different pH media. Sunset Yellow in 0.5 M NH4Cl/NH3 buffer solution gave an adsorptive stripping voltammetric peak at the hanging mercury drop electrode at -0.60 V using an accumulation potential of -0.40 V. The effect of experimental parameters that affected this determination are discussed. The calibration graph to determine Sunset Yellow was linear in the range 5-90 mu g l(-1), obtaining a relative standard deviation of 2.2% for a solution of 30 mu g l(-1) (n = 10) in the same day. The determination limit was 5 mu g l(-1) after 15 s of accumulation at -0.40 V. The proposed method was applied to determine this dye in several commercial refreshing drinks, which contained small amounts of this compound. Measurements were made directly over diluted solutions of commercial samples. Similar results were obtained between adsorptive stripping square-wave voltammetric values and the obtained by application of a HPLC method with spectrophotometric detection. (C) 1997 Elsevier Science B.V.