Simultaneous Determination of Residual Spiramycin and Tylosin in Aquatic Products by HPLC

Residual spiramycin and tylosin in sample were extracted with ethyl acetate from phosphate buffer solution of pH 8,and defatted with n-hexane.The sample solution in the phosphate buffer was then purified by passing through HLB column.The objective analytes on the column were eluted with a solution of triethylamine in methanol.The eluate was blown with nitrogen to dryness at 40 ℃,and residue was taken up with the mobile phase and ready for HPLC determination.The Meck Purospher STAR RP18 column (250 mm×4.6 mm,5 μm) was used as chromatographic column,and gradient elution with mixed solutions of acetonitrile and phosphate buffer solution (pH 2.5) in different ratio was applied in the separation.UV-detections were made at 232 nm for spiramycin and at 287 nm for tylosin.Linear relationships between peak area and concentration of both the compounds were found in the range within 200 ng (r=0.999 9).Detection limits for spiramycin and tylosin were found to be 0.005 4 mg·kg-1 and 0.031 mg·kg-1 espectively.Tests for precision and recovery were made,and the results obtained were in the ranges of 6.24%-9.83% and 82.2%-89.0% respectively.