基于纳米银/聚L-谷氨酸修饰玻碳电极的电化学传感器用于泡菜中亚硝酸钠含量的测定

Determination of Sodium Nitrite in Pickle by Electrochemical Sensor Based on Nano-Ag/Poly L-Glutamic Acid Modified Glass Carbon Electrode

采用电沉积和电聚合的方式,将纳米银和L-谷氨酸修饰在玻碳电极上,制得纳米银/聚L-谷氨酸修饰玻碳电极(Poly-L-Glu/Nano-Ag/GCE)。以0.2 mol·L^(-1)磷酸盐缓冲溶液(pH 7.0)为支持电解质,以Poly-L-Glu/Nano-Ag/GCE为工作电极,饱和甘汞电极为参比电极,铂电极为辅助电极,在最佳检测条件下,采用循环伏安法进行测定。结果表明:Poly-L-Glu/Nano-Ag/GCE对亚硝酸钠具有较好的选择性,亚硝酸钠的浓度在4.14×10^(-6)~1.35×10^(-3) mol·L^(-1)内与对应的氧化峰电流的绝对值呈线性关系,检出限(3s/k)为4.14×10^(-7) mol·L^(-1),并且该电极的制备方法具有较好的重复性。将PolyL-Glu/Nano-Ag/GCE用于泡菜样品中亚硝酸钠的测定,检出量为1.33×10^(-5) mol·L^(-1),加标回收率为98.9%~103%。

Nano-Ag/poly L-glutamic acid modified glass carbon electrode(Poly-L-Glu/Nano-Ag/GCE)was prepared by the means that nano-Ag and L-glutamic acid were modified on glass carbon electrode by electrochemical deposition and polymerization.Using 0.2 mol·L-1 phosphate buffer solution(pH 7.0)as the supporting electrolyte,the cyclic voltammetry was used for determination under the best detection conditions with Poly-L-Glu/Nano-Ag/GCE as the working electrode,saturated calomel electrode as the reference electrode and platinum electrode as the auxiliary electrode.It was shown that Poly-L-Glu/Nano-Ag/GCE had good selectivity for sodium nitrite,and linear relationship between concentration and the absolute value of corresponding oxidation peak current of sodium nitrite was kept in the range of 4.14×10-6-1.35×10-3 mol·L-1,with detection limit(3s/k)of 4.14×10-7 mol·L-1.The preparation method of the electrode had good repeatability.Poly-L-Glu/Nano-Ag/GCE was used for determination of sodium nitrite in pickle sample,giving results of detection amount of 1.33×10-5 mol·L-1,and the spiked recoveries in the range of 98.9%-103%.