Quantitative determination of carmine in foods by high-performance liquid chromatography

A simple and rapid method has been developed and validated for the determination of carmine in foods. Samples were homogenised and extracted with 0.05 M NaOH, followed by centrifugation. The resulting solution was filtered and injected to HPLC. Carmine was separated by HPLC using an NovaPak C18 column coupled to a photodiode array detector. The contents of carmine were finally quantified using corresponding calibration curves over ranges of 1.0-100 μg ml(-1), with good correlation coefficients (r(2)=0.9999). The recoveries of carmine from foods spiked at levels of 10, 50, and 100 μg g(-1) which ranged from 90.4% to 96.2% with relative standard deviations between 2.8% and 6.8%. Limit of detection and limit of quantification of carmine were 0.4 and 1.0 μg ml(-1), respectively. This method was found to be useful to distinguish carmine from carminic acid, a major component of cochineal extract. The method has been successfully applied to various foods.