RESUMO
This works presents a novel screen-printed carbon electrode modified with nickel hydroxide nanoparticles and chitosan (Ni(OH)2/CS/SPCE) for the non-enzymatic flow injection amperometric detection of glucose. The electrode was modified by drop-casting a suspension of the synthesised nanocomposite onto the screen-printed electrode and dried for 1 hour at room temperature. EDX analysis was used to investigate the chemical composition of the electrode before and after modifying. The electrochemical response of the unmodified SPCE and modified electrode was initially investigated by cyclic voltammetry (CV) using 0.1 M NaOH as the supporting electrolyte. CVs showed catalytic activity for glucose oxidation using the Ni(OH)2/CS/SPCE at 0.55 V. During flow injection analysis (FIA), 0.60 V and 1.5 mL min-1 were identified as the optimal potential and flow rate, respectively. A wide linear range of detection was observed (0.2 to 10.0 mM) with a sensitivity and limit of detection of 913 µA mM-1 cm-2 and 0.0174 mM, respectively. The modified electrode also displayed excellent repeatability (RSD = 0.47%, n = 20) and good reproducibility (RSD = 2.52%, n = 6). The modified electrode was shown to be very selectivity for glucose over other interferences commonly found in human blood samples. The practicality of the developed flow injection-amperometric system (FIA-Amp) was validated by the quantification of glucose in real serum samples, where results were in close agreement with those obtained from the local hospital.