CHLORTETRACYCLINE, OXYTETRACYCLINE, AND TETRACYCLINE IN EDIBLE ANIMAL-TISSUES, LIQUID-CHROMATOGRAPHIC METHOD - COLLABORATIVE STUDY

Thirteen laboratories analyzed samples of edible animal tissues for te tracycline residues, The method included extraction of analytes into b uffer, elution from a C-18 solid-phase extraction (SPE) cartridge, and reversed-phase liquid chromatographic (LC) analysis, including use of a confirmation column, An additional laboratory, using an alternative LC assay based on a different sample cleanup, also analyzed the sampl es, Results showed the 2 methods are comparable, The LC method for det ermination of cholortetracycline, oxytetracycline, and tetracycline in edible animal tissues has been adopted by AOAC INTERNATIONAL, Results from 13 laboratories indicate that the method under study provides ge nerally better results at the higher concentrations tested than at con centrations near the detection limit and that there is less problem wi th interferences in muscle tissue than in kidney, The method can achie ve reliable results for analytes and matrixes studied at concentration s from 0.1 to 0.6 ppm and above, depending on the analyte-matrix combi nation, with generally better performance to be expected with muscle t han with kidney, The poorer performance for fortified samples, particu larly kidney, was attributed to additional homogenization steps requir ed to prepare these samples, Recovery of analytes from different lots of solid-phase extraction (SPE) cartridges was an important variable.