A glassy carbon electrode modified with nanoporous PdFe alloy for highly sensitive continuous determination of nitrite

Nanoporous palladium-iron alloy (np-PdFe) was fabricated by dealloying. It possesses a three-dimensional nanospongy architecture with a typical dimension of similar to 5 nm and displays a high catalytic activity towards oxidation of nitrite in phosphate buffer of pH 7.0 at a working voltage of 1.2 V (vs. the reversible hydrogen electrode). Compared to np-Pd and a commercial Pd/C catalyst, the np-PdFe alloy exhibits superior detection capability such as a wide linear range (that extends from 0.5 to 25.5 mM), fast amperometric response (within 2 s), and a low detection limit (0.8 mu M). Long-term tests demonstrate that the np-PdFe alloy has improved reproducibility and durability, with almost no activity loss upon continuous nitrite detection for two weeks. The method was applied to determine nitrite in sausage and the results are in good agreement with those of the Griess method.