A facile method to anchor reduced graphene oxide polymer nanocomposite on the glassy carbon surface and its application in the voltammetric estimation of tryptophan in presence of 5-hydroxytryptamine

A 4-amino-3-hydroxy-1-naphthalenesulfonic acid (AHNSA) and reduced graphene oxide (rGO) based polymer nanocomposite (PNC) has been electrodeposited directly on the surface of glassy carbon electrode (GCE) using cyclic voltammertry. The electrochemical reduction of graphene oxide (GO) to rGO and the synthesis of PNC have been inspected using FE-SEM, TEM and Raman spectroscopy. The modified GCE was further used for the voltammetric quantification of Tryptophan (Trp) in the presence and absence of 5-hydroxytryptamine. The PNC modified sensor exhibited improved sensing and electrocatalytic properties in comparison to unmodified GCE, rGO modified GCE and AHNSA modified GCE. The fabricated sensor showed a linear calibration plot in the range of 0.5-200 μM with sensitivity and limit of detection (L.O.D.) of 0.0451 μA μM^-1 and 316 nM (n = 3) respectively in comparison to 0.19 μA μM^-1 and 2.54 μM (n = 3) respectively for unmodified GCE. The proposed method was also successfully applied for the determination of Trp in commercially available pharmaceutical formulations, human urine and plasma samples.