Determination of synthetic dyes in ice-cream by capillary electrophoresis

A capillary electrophoresis method was developed to analyse same food dyes in ice-cream. Sunset yellow (E110), carmoisine (E122), Ponceau 4 R (E124), are permitted in ice-cream by directive 95/45/ce of Commission 26-7-95, but their maximum amount (50 μg/kg) is lower of the limit for the other permitted (150 μg/kg). In this paper we propose a separation on a capillary column (50 cm×70 μm I.D.) with photodiode array detection: each peak is identified from absorbance spectra and then quantified by external standard. The electrophoresis buffer used was a mixture of 25 mM sodium phosphate and 25 mM sodium borate (1:1) pH 8. The three dyes are separated in a short time, <6 min the standard deviations of the migration times of the peaks range between 0.3% and 0.7%. The limit of detection with a 3:1 signal-to-noise ratio was 5 μg/kg. This capillary zone electrophoresis procedure resulted rapid and sensitive.