| Abstract: | Anthranilic acid occurs in excised swine livers as a result of temperature abuse before and/or after freezing. The tryptophan metabolite is the major source of the variable non-sulfonamide background level frequently encountered in the Tishler method for determining sulfonamide residues in swine livers. Diazotized anthranilic acid reacts slowly with N-1-(naphthyl)ethylenediamine [k(s-1) = 5.79 (+/- 0.07) X 10(-5)] and the final background level depends on the time elapsed between addition of the coupling agent and spectrophotometric determination. Kynurenine was tentatively identified as a minor source of the non-sulfonamide background level. |
