Fluorescence-Based Determination of Agmatine in Dietary Supplements

This study presents an optical determination of agmatine at pH 13. The fluorescent product formed between the indicator reagent o-phthaldialdehyde and agmatine sulfate reached its maximum intensity within twenty minutes of incubation time when excited at 340 nanometers. The determination of agmatine sulfate was linear within a concentration range between 6.0x10(-7) and 8.0x10(-6)moles per liter and the limit of detection was 1.5x10(-8) molar. Under the optimized conditions, the fluorescent intensity of o-phthaldialdehyde in the presence of other biogenic amines (histamine, tyramine, putrescine, noradrenaline, etc.) was at least fourteen-fold lower than that of the o-phthaldialdehyde-agmatine sulfate product. The method was applied for the determination of agmatine sulfate in dietary supplements.