Fluorometric Determination of Histamine in Tuna: Development of Method

Abstract

Tuna extracts are treated with an anion exchange resin to remove interfering materials, histamine is derivatized with o-phthalaldehyde, and the fluorescence of the resulting compound is measured fluorometrically. Replicate analyses of acceptable and decomposed tuna packed in oil or water agreed within 1 mg at a level of 10 mg/100 g and within 12 mg at a level of 100 mg/100 g. Recoveries of histamine added to fish were >90 and >83% at levels of 10 and 100 mg/100 g, respectively. The new method is more rapid and specific and is simpler than previous methods because no liquid-liquid extractions or chromatographic separations of histamine are required. The sensitivity of the method allows quantitation of <10 mg histamine/100 g sample. The accuracy and precision of the fluorometric method are comparable to those of the official AOAC colorimetric method.