A new liquid-liquid extraction method for determination of 6 azo-dyes in chilli products by high-performance liquid chromatography

► A liquid-liquid extraction method was established for purification and enrichment of 6 azo-dyes. ► Formic acid and chloroform were used as extraction/clean-up solvents, which had the capability to provide different type of interactions with the azo-dyes. ► The simultaneous extraction, purification and enrichment of azo-dyes were successfully achieved in the sample preparation process, and satisfied results were obtained.