Development and validation of HPLC method to measure active amines in plant food supplements containing Citrus aurantium L

Citrus aurantium L. (bitter orange) is frequently used as an ingredient of food supplements aimed to reduce body weight or improve general physical performances. The most active compounds of C. aurantium are amines having adrenergic activity: octopamine, synephrine, tyramine, N-methyl-tyramine and hordenine. The quantification of these amines is critical since their content in food supplements is regulated by national/international rules. Some methods for the quantification of C. aurantium amines have been published, including the official method developed by AOAC, but most of them are not totally satisfactory for the analysis of complex matrixes, such as extracts or food supplements. HPLC–UV–fluorescence procedure has therefore been developed; the method is quick and simple, and allows the analysis of samples after a rapid extraction procedure without any further cleaning step. The assay, using one or two detectors, showed good results during the validation tests performed according to the FDA guidelines.