Effect of nucleophilic agents and organized media on the fluorimetric determination of histamine with o-phthalic aldehyde

The addition of nucleophilic agents, 2-mercaptoethanol, 3-mercaptopropionic acid (3-MPA), and N-acetyl cysteine, to the system histamine-o-phthalic aldehyde (OPA) resulted in the following effects: the exclusion of the acidification step, the 1.5-2-fold increase in the time of attaining the optimum fluorescence, the shift of the pH of fluorophore formation of a less alkaline region by 2 units and the widening of its range by two to three times, and the twofold increase in the fluorophore stability (in time in the case of 3-MPA). The addition of surfactant micelles reduced the time of attaining the optimum fluorescence intensity by two times, but its intensity increased (by a factor of 1.3–1.5) only in the presence of nonionic surfactant block copolymers. The widest plateau range (2 pH units), the highest stability of an analytical signal in time (3 h), and the best reaction sensitivity were obtained after the addition of 2-hydroxypropyl-β-cyclodextrin to the histamine-OPA-3-MPA system. Procedures were proposed for the determination of histamine in fish products and wine using nucleophilic agents and different organized media.