Ascorbic acid does not necessarily interfere with the electrochemical detection of dopamine

Abstract

It is widely stated that ascorbic acid (AA) interferes with the electrochemical detection of neurotransmitters, especially dopamine, because of their overlapping oxidation potentials on typical electrode materials. As the concentration of AA is several orders of magnitude higher than the concentration of neurotransmitters, detection of neurotransmitters is difficult in the presence of AA and requires either highly stable AA concentration or highly selective neurotransmitter sensors. In contrast to the common opinion, we show that AA does not always interfere electrochemical detection of neurotransmitters. The decay of AA is rapid in cell culture medium, having a half-time of 2.1 hours, according to which the concentration decreases by 93% in 8 hours and by 99.75% in 18 hours. Thus, AA is eventually no longer detected by electrodes and the concentration of neurotransmitters can be effectively monitored. To validate this claim, we used unmodified single-wall carbon nanotube electrode to measure dopamine at physiologically relevant concentration range (25–1000 nM) from human midbrain organoid medium with highly linear response. Finally, AA is known to affect dopamine oxidation current through regeneration of dopamine, which complicates precise detection of small amounts of dopamine. By designing experiments as described here, this complication can be completely eliminated.