Voltammetric sensor based on electropolymerized poly(Neutral Red) and pillar[3]arene[2]hydroquinone ammonium derivative for dopamine and ascorbic acid determination

The approaches to the synthesis of newly obtained pillar[3]arene[2]hydroquinone and its derivative with functional ammonium substituents (P[3]A[2]HQae) are suggested. The structures of the macrocycles synthesized were confirmed and characterized by a complex of physical methods. P[3]A[2]HQae has found its application as an electron transfer mediator for the determination of dopamine and ascorbic acid with the voltammetric sensor developed. For a successful sensor assembly the glassy carbon electrode (GCE) was modified with carbon black (CB), P[3]A[2]HQae and electropolymerized form of Neutral red (polyNR). P[3]A[2]HQae demonstrated better mediator properties compared to unsubstituted pillar[5]arene due to the 5–6-fold increase in the redox currents of Neutral red (NR) during its electropolymerization. Under optimal conditions the sensor allowed performing the determination of dopamine and ascorbic acid in the ranges from 10 nM to 1.0 mM and from 1 nM to 1 mM, respectively. The limits of detection were of 10 nM for dopamine and and 1 nM for ascorbic acid. The polyNR peaks positions after its interaction with the analytes provided the opportunity to discriminate the sensor response towards dopamine and ascorbic acid. The possibility of dopamine and ascorbic acid determination in real drug samples was demonstrated.