Development and Validation of a Quantitative Method for Determination of Carmine (E120) in Foodstuffs by Liquid Chromatography: NMKL Collaborative Study

Abstract

A liquid chromatographic method for quantitative determination of carmine (E120) in different foodstuffs is described. Qualitative and semiquantitative methods for analysis of carmine and other related dyes are well established. However, quantitative methods available are based mainly on enzymatic reactions that are time-consuming or specific for analysis of carminic acid in yoghurt. In the method developed and validated here, carminic acid is extracted by boiling the sample with HCl, purified on a solid-phase extraction cartridge, and injected on a C18 analytical column. The method was evaluated by an internal analytical quality control and a collaborative study in which 11 laboratories from the Nordic countries participated. The food samples analyzed were fruit jelly, liqueur, juice, yoghurt, and ice cream. Materials were distributed to participants as uniform level and split level. Validation showed that the proposed method is well suited for quantitative determination of carmine. The detection limit is 0.1 mg/L. The mean relative standard deviation for reproducibility varies from 7.9 to 11.7%. The proposed method is simple and relatively fast compared with previously published methods.