Determination of citrus red 2 in citrus by high pressure liquid chromatography.

Objective To establish a rapid method for the determination of citrus red 2(CR2) in citrus by high pressure liquid chromatography(HPLC). Methods The samples were extracted with acetonitrile,cleaned-up by NH2 solid phase extraction cartridge. Then, the samples were separated on a Waters Sunfire C18(250mm×4.6mm, 5.0μm) in gradient elution with the mobile phases of water and acetonitrile. The separated compounds were detected with UV/VIS detector. The linearity of the method(r=0.99973) was good over the concentration range from 0.5 to 5.0μg/mL for CR2. The limit of detection(LOD) was 0.003mg/kg, and the limit of quantification(LOQ) was 0.01mg/kg. Results The average recoveries of CR2 at 3 levels of 0.1, 0.5 and 2.0mg/kg were between 79.48% and 93.20% with the relative standard deviations(RSDs) between 6.5%and 14.5%. A total of 36 citrus samples randomly collected from different markets were detected by the proposed method. The results showed that 3 samples contained citrus red 2. Conclusion The sensitivity, accuracy,and precision of this method could meet the requirements of the CR2 analysis.