Determination of Seven Inedible Pigments in Food Using High Performance Liquid Chromatography

A method for the simultaneous determination of seven inedible pigments (Auramine O, Basic orange, Acid orange II, Acid golden yellow G, Rhodamine B, Para Red, Sudan I) in food was developed using high performance liquid chromatograph with ultraviolet-visible detector. Acetonitrile, methanol and basic methanol were used to extract the inedible pigments from bean and meat products. Acetonitrile and 70% acetonitrile-water were used to extract the inedible pigments from condiments. Using SunFire TM C-18 (250 mm x 4.6 mm, 5 mu m), methanol-50 mmol/L ammonium acetate (adjust pH to 4.5 with phosphoric acid) as the mobile phase with a gradient elution at the rate of 1 mL/min and detected at the wavelength of 450 and 520 nm. The linear ranges of seven inedible pigments were well with correlation coefficient above 0.998. The limit of detection (LOD) of seven inedible pigments was 0.01 mg/L to 0.1 mg/L and the limit of quantification (LOQ) was 0.18 mg/kg to 1.25 mg/kg. The average recoveries of seven inedible pigments were above 80%. The RSD (n=3) was from 2.0% to 5.7%.