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

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%.