Detection of o-tyrosine in irradiated chicken by reverse-phase HPLC and fluorescence detection

A method for the measurement of o-tyrosine in irradiated chicken has been developed. The procedure involves the solvent extraction and removal of free o-tyrosine, which is present in unirradiated tissue, followed by acid hydrolysis of bound o-tyrosine in the proteinaceous residue and measurement of the cleaved residues by HPLC with fluorescence detection. Bound o-tyrosine was not detected above 0.01 mg/kg in unirradiated tissue but was observed, in increasing amounts of up to 5.18 mg/kg, when the tissue was irradiated at doses of between 2.5 and 20 kGy. The precision of the analysis was assessed by duplicate determinations, the agreement between duplicates and their respective means averaged 1.7% as defined by the term [(a-b)/(a+b)] x 100% where a and b are the repeat determination values.