HPLC Determination of 3 Alkali Orange Dyestuffs in Foodstuffs

HPLC was applied to the determination of 3 alkali orange dyestuffs, namely chrysoidine G (CDG), astrazon orange G (AOG) and astrazon orange R (AOR), which were added contrabandly to foodstuffs as colorants. The homogenized sample (20.00 g) was mixed with 2 g of anhydrous Na2SO4 and extracted thrice ultrasonically with absolute alcohol (30 mL+30 mL+30 mL). The extracts were combined and evaporated first at 45 ℃ in vacuum and then by N2-blowing to dryness. The residue was taken up with the mobile phase (mix 0.02 mol·L-1 NH4OAc solution with methanol in the ratio of 39+61 by volume) and made up to 5 mL. After centrifugation, the supernatant was used for HPLC analysis by separation on Agilent C18 column. Diode array detector was used for the determination of CDG at 430 nm and of AOG as well as AOR at 480 nm. Linearity ranges for the 3 dyestuffs were found to be same between 0.50 to 20.0 mg·L-1, with detection limits (3S/N) of 0.10 mg·L-1. Tests for recovery and precision were performed by addition of standards to a sample of yellow croaker, and the results of average recovery found were 91.2%, 93.6% and 96.0% for the 3 dyestuffs respectively, with RSD′s (n=6) less than 2%.