Simultaneous voltammetric determination of nitrophenol isomers based on a modified electrode by silver nanowires and poly-L-arginine
A novel-modified electrode was constructed for simultaneous determination of 4-nitrophenol (4NP) and 2-nitrophenol (2NP). A glassy carbon electrode (GCE) was modified by silver nanowires and poly-L-arginine (poly-L-Arg/AgNWs/GCE). Compared to GCE, the modified electrode showed more sensitive peak currents for the oxidation and reduction of nitrophenol isomers. Well-resolved oxidation peaks were appeared in cyclic voltammetry at +0.08 V (4NP) and at −0.32 V (2NP). Under optimised experimental conditions, calibration curves were obtained for the two isomers. The linear concentration range was 1.0–210 μM for 4NP, and 3.0–210 μM for 2NP, with limits of detection (LOD) as 0.9 μM and 1.0 μM, respectively. The application of the method to simultaneous determination of nitrophenol isomers in tap and river water samples was satisfactory. Low concentrations of 2NP and 4NP were spiked to the real samples and their recoveries were calculated by the proposed method. The recoveries in tap and river water samples were found to be 96.92% and 104.98% for 4NP (2.0 μM), and 95.31 and 103.88 for 2NP (3.0 μM), respectively. Relative standard deviations were calculated for three replicate measurements of the spiked nitrophenols which were between 3.50% and 4.73%. The sensor showed a long-term stability of more than 1 month.