聚罗丹明B/碳纳米管修饰玻碳电极对亚硝酸盐的灵敏检测

摘要

以聚罗丹明B/碳纳米管复合材料修饰玻碳电极(PRhB/CNTs/GCE)为工作电极,通过电催化氧化法应用于亚硝酸盐的灵敏检测.采用循环伏安法(CV)、示差脉冲伏安法(DPV)和安培法考察了NO2-在PRhB/CNTs/GCE上的电化学行为和电催化机理.研究结果表明,与单一PRhB/GCE相比,NO2-的氧化电压明显下降(124 mV),氧化电流提高79％.PRhB/CNTs/GCE对亚硝酸盐的电催化氧化机理是2电子参与的不可逆反应.采用DPV法检测高浓度NO2,氧化电流与多种NO2-浓度区间呈良好的线性关系,线性范围分别为2～25 μmol/L(Ip=94.92 cNO2-+ 0.05,r2=0.992 3)、35～500 μmol/L(Ip=20.32cNO2-+2.65,r2=0.995 8)和500～8 000 μmol/L(Ip=10.74cNO2-+8.64,r2=0.997 7).采用安培法检测低浓度NO2-,其线性范围为0.25～5 μmol/L(Ip=0.14cNO2-+0.01,r2=0.993 5),灵敏度为143.50 μA·L·mmol-1,方法检出限低至0.08μmol/L.该PRhB/CNTs/GCE具有良好的选择性、抗干扰能力和稳定性,成功应用于实际样品中亚硝酸盐的定量测定,加标回收率为98.3％～ 102.0％.%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 NO2-i-ons 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 NO2-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 NO2-i-ons were determined by differential pulse voltammetry,and the oxidation current of NO2-ions was linearly proportional to its concentration in the ranges of 2-25 μmol/L (Ip =94.92cNO2-+ 0.05,r2 =0.992 3),35-500 μmol/L(Ip =20.32CNO2-+2.65,r2 =0.995 8) and 500-8 000 μmol/L(Ip =10.74CNO2-+ 8.64,r2 =0.997 7),respectively.Low concentration of NO2-ions were detected by amperometry with a linear range of 0.25-5 μmo]/L (Ip =0.14CNO2-+ 0.01,r2 =0.993 5).The sensitivity was 143.50 μA · L · mmol-1,and the limit of detection was as low as 0.08 μ mol/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％.