Abstract:

Glassy carbon electrode surface was modified with L-cysteine by means of cyclic voltammetry to prepare polymer film-modified electrode, and then the electrode was used to construct a novel nitrite amperometric sensor. The electrocatalytic activity of poly(L-cysteine) film electrode toward NO2 was studied in detail through cyclic voltammetry. A method for determination of nitrite in food using the amperometric sensor was built. The results indicated that the sensor shows an excellent amperometric response to NO2 in phosphate buffer (PB) at pH 3.0; A good linear relationship over a NO2 concentration range from 9.0×10-7 mol/L to 1.49×10-5 mol/L is obtained, and the detection limit is 1.0×10-7 mol/L (S/N=3). The sensor shows high sensitivity, good linearity, low detection limit and good selectivity. It was used for quantitative analysis of NO2 in food samples with satisfying results.

Key words: L-cysteine, nitrite, amperometric sensor, electropolymerization