Table 5.

Summary of the electrochemical parameters of the SPEs modified with different preparations of NiO for the detection of 20 mmol [Fe(CN)₆]^3−/4− solution in 50 mM phosphate buffer with 0.1 M KCl at pH of 7.4. The anodic peak potential (E_pa), the cathodic peak potentials (E_pc), the peak-to-peak separation (ΔE_p), the anodic peak intentsity (I_pa), and the cathodic peak intentsity (I_pc) for each sample were obtained at a scan rate of 100 mV S^–1.

Sample	Epa (V)	Epc (V)	ΔEp (V)	Ipa (μA)	Ipc (μA)
A4	0.185	0.062	0.123	26.97	−19.65
U4	0.185	0.082	0.103	29.80	−23.23
A6	0.457	−0.361	0.818	15.32	−5.19
U6	0.246	0.056	0.190	15.49	−8.00