Construction of a carbon paste electrode based on ionic liquid for trace electrochemical detection of nitrite in food samples

Abstract

A new carbon paste electrode based on the use of an ionic liquid as the binder is introduced. The composite electrode consists of graphite and n-octylpyridinium hexafluorophosphate (an ionic liquid). The behavior of the n-octylpyridinium hexafluorophosphate carbon paste electrode (OPFP-CPE) towards [Fe(CN)₆]^3−/4− was tested. This novel electrode has conductivity similar to glassy carbon electrode (GCE). It shows low background current and well defined voltammograms for the [Fe(CN)₆]^3−/4−. The oxidation of nitrite was studied on the OPFP-CPE in aqueous solution using cyclic voltammetry (CV), differential pulse voltammetry (DPV), and chronoamperometry (CA). The proposed method was used for determination of nitrite in food samples (ham sausage) containing nitrite. Nitrite can be determined in the ranges of 1.0 × 10⁻⁴ to 1.0 × 10⁻³ M by CV, 1.0 × 10⁻⁶ to 2.0 × 10⁻⁴ M by DPV and 7.6 × 10⁻⁶ to 1.4 × 10⁻⁴ M by CA, with the detection limits of 3.0 × 10⁻⁵ M, 1.0 × 10⁻⁷ M, and 4.0 × 10⁻⁷ M (calculated by 3σ) for CV, DPV, and CA, respectively. The recovery of spiked nitrite to the ham sausage extract was from 90.00% to 109.76%.