OPTIMIZATION AND AUTOMATION OF AOAC OFFICIAL METHOD 971.47 FOR DETERMINATION OF ROXARSONE IN FEED

AOAC Official Method 971.47 was optimized for use with solid-phase ext raction (SPE) using the same activated carbon referenced in the origin al method, The optimization of AOAC 971.47 begins after the roxarsone is extracted into the 2% K2HPO4 solution of the original method; inste ad of 30 mL, 9 mL is pipetted into a test tube, Next, to flocculate th e protein, 300 mu L HCl is pipetted info the tube and mixed, After 15 min, the contents of the tube are filtered through a 0.45 mu m nylon m embrane filter equipped with a glass prefilter, Next, 7 mL clear filtr ate is pipetted into a new test tube, followed, by the addition of 234 mu L NaOH, and the contents of the tube are mixed, The filtrate is th en passed through a 400 mg bed of activated carbon packed in a 3 mL SP E tube at a flow rate of 1 mL/min. The spectrophotometric analysis of the e(sic)uate is not changed from the original AOAC 971.47, The optim ized method was validated and semiautomated, Results of roxarsone dete rmination by the optimized procedure were found to be acceptable at al l levels of approved claims, For the commercial feed samples analyzed, recoveries by the automated method ranged from 93.1 to 104% of the re sults reported by an independent laboratory using AOAC 971.47.