Quantitative determination of biogenic amine at gold in the presence of secondary amine during electrochemical oxidation in physiological solution containing ascorbic and uric acids

Electrooxidation of epinephrine (EP) in the presence of secondary amine as a nucleophile was investigated on a bare polycrystalline gold electrode in a phosphate buffer solution of pH 7. The results have shown that electrochemically produced epinephrinequinone underwent an attack by morpholine (MO) via 1,4-Michael addition. The reaction products were identified by electrospray ionisation mass spectrometry (ESI-MS). A linear relationship between the current response and epinephrine concentration in the presence of morpholine was obtained in the range of 2 × 10−5 mM to 0.7 mM with the detection limit 1.5 × 10−5 mM. The procedure of using morpholine as an additive in analysed solutions was proven to be suitable for quantitative epinephrine determination in samples containing an excess of the ascorbic acid (AA) and uric acids (UA) without the necessity of any preceding modification of a gold electrode surface.

► Epinephrine as a neurotransmitter.
► Catalytical electrooxidation of epinephrine at unmodified gold electrodes.
► 1,4-Michael addition of secondary amine as a nucleophile.
► Epinephrine oxidation in the presence of interfering compounds.