SIMULTANEOUS HPLC DETERMINATION OF PARA-RED AND SUDAN RED DYESTUFFS IN FOODSTUFFS AFTER PURIFICATION WITH GEL PERMEATION CHROMATOGRAPHY

A study on the simultaneous determination of para red and sudan red dyes (in cluding sudan Ⅰ,Ⅱ,Ⅲ and Ⅳ) by HPLC with diode array detector after purification with gel permeation chromatography was reported in this paper.Samples were extracted directly with a mixture of cyclohexane-athylacetate (1+1) and purified by passing through a column packed with Bio-beads SX3 gel,to remove interfering high molecular fatty substances and natural colorants in food samples.Chromatographic column of Zorbax SB C18 (4.6 mm×250 mm,5 μm) was applied,and aqueous solution of acetonitrile,containing 3 drops of acetic acid (pH 4.0) was used as mobile phase in the gradient elution.Multiwavelength diode-array detection was applied in the determination of the 5 compounds mentioned above.Linear relationships in the range from 0.1 to 10 mg·L-1 of either of the 5 compounds were obtained with correlation coefficients (r) larger than 0.999.RSD′s obtained were in the range of 1.35% to 357%,and average recoveries were in the range of 88.6% to 99.2%.Detection limits were found to be 1.8 μg·kg-1,5.0 μg·kg-1,9.5 μg·kg-1,8.0 μg·kg-1 and 6.5 μg·kg-1 for para red,sudan Ⅰ,sudan Ⅱ,sudan Ⅲ and sudan Ⅳ respectively.