Histamine and histidine determination in tuna fish samples using high-performance liquid chromatography. Derivatization with omicron-phthalaldehyde and fluorescence detection or UV detection of "free" species.

A rapid and simple HPLC procedure for the simultaneous determination of histamine and histidine is presented. Sample extraction, extract purification, derivatization and reversed-phase chromatographic determination are described. Also the analysis of "free" (i.e. not derivatized) species with UV detection is discussed, and the two procedures are compared. A derivatization step involves more difficulties in terms of linearity and reproducibility because of the great unstability of omicron-phthalaldehyde derivatives but presents many advantages due to the good separation between histamine and histidine as far as the increased sensitivity is concerned. The first results of canned tuna samples analysis are presented and discussed.