Sensitive Detection of Nitrite Using a Polyrhodamine B/Carbon Nanotubes Modified Glassy Carbon Electrode

KeyWord:polyrhodamine B  carbon nanotubes  nitrite  electrochemical detection  chemical modified electrode  electropolymerization

Abstract:

      The sensitive detection of nitrite was carried out by electrocatalytic oxidation with a polyrhodamine/carbon nanotubes composite materials modified glassy carbon electrode(PRhB/CNTs/GCE) as working electrode.The electrochemical behavior and electrocatalytic mechanism of NO-2 ions were investigated at the PRhB/CNTs/GCE through cyclic voltammetry(CV),differential pulse voltammetry(DPV) and amperometry.The results showed that the oxidation potential of NO-2 ions was obviously decreased(124 mV) and the oxidation current was improved 79%at the PRhB/CNTs/GCE in comparison with individual PRhB/GCE,mainly due to the synergistic catalytical effect of polyrhodamine and carbon nanotubes.The electrocatalytical mechamism of nitrite at the PRhB/CNTs/GCE was an irreversible reaction where two electrons involved.High concentration of NO-2 ions were determined by differential pulse voltammetry,and the oxidation current of NO-2 ions was linearly proportional to its concentration in the ranges of 2-25 ¦Ìmol/L(Ip=94.92cNO-2+0.05,r2=0.992 3)£¬35-500 ¦Ìmol/L(Ip=20.32cNO-2+2.65,r2=0.995 8) and 500-8 000 ¦Ìmol/L(Ip=10.74cNO-2+8.64,r2=0.997 7),respectively.Low concentration of NO-2 ions were detected by amperometry with a linear range of 0.25-5 ¦Ìmol/L(Ip=0.14cNO-2+0.01,r2=0.993 5).The sensitivity was 143.50 ¦ÌA¡¤L¡¤mmol-1,and the limit of detection was as low as 0.08 ¦Ìmol/L.Furthermore,the proposed PRhB/CNTs/GCE exhibited excellent selectivity,good reproducibility,anti-interference property and long-term stability.It was successfully applied in the analysis of nitrite in real water samples,with spiked recoveries of 98.3%- 102.0%.