Analysis of Agmatine by UV-Visible Absorption Spectrophotometry and Detailed Interference Study on Biogenic Amines and Salts: Grape Application

The aim of this work is to develop a new method for the analysis of agmatine from UV-Visible absorption spectra. The optimization of the analytical parameters shows that the stoichiometry of the orthophthalaldehyde-agmatine complex is 1:1, the optimal pH is equal to 11 and the stability time is about 10 minutes. The analytical performances obtained are satisfactory with very low limit of detection (LOD) and limit of quantification (LOQ) respectively equal to 0.121 µg/mL and 0.405 µg/mL. The relative standard deviation (RSD) obtained of 2.1% shows the good reproducibility of the measurements. Interference effects show that the aromatic biogenic amines interfere less than linear ones, excepted serotonine. Similarly, a more marked interference is found for chloride salts. Finally, a recovery rate of between 99.4% and 111.7% was found in the grape extract studied, showing the effectiveness of the method.