Fortified versus incurred residues: extraction of furazolidinone metabolite from prawn.

Most methods reported in the literature for determination of nitrofuran metabolites use the same extraction and derivatisation conditions to hydrolyse and extract the protein-bound residues from animal tissue. While undertaking certification of reference materials for nitrofuran metabolites in freeze-dried prawn, it was found that these conditions are satisfactory for recovery of spiked residues; however, extraction efficiencies of incurred furazolidinone could be substantially increased by further optimisation of the extraction conditions. The availability of a suitable certified reference material allows laboratories to ensure that their method is optimised for incurred residues.