Determination of nitrofurans residues in animal feeds by flow injection chemiluminescence procedure

A simple flow injection chemiluminescence (FI-CL) method was developed for the rapid and sensitive determination of nitrofurans, including furazolidone, nitrofurantoin and nitrofurazone, in animal feeds based on its chemiluminescence induced by potassium permanganate in sulphuric acid medium. The method involves the injection of nitrofuran samples or standards into H2SO4 carrier stream, which then merges at a T-piece with a reagent stream consisting of KMnO4 in the H2SO4 carrier solution. The elicited chemiluminescence intensity of the resulting reaction mixture was measured by photomultiplier tube operated at a voltage of 950 V. Optimum CL signals were given using 2.5 × 10−5 mol L−1 potassium permanganate in 0.1 mol L−1 sulphuric acid as an oxidant stream and a carrier stream of 0.1 mol L−1 sulphuric acid with a total flow rate of 7.0 mL min−1. Results detailing the optimisation of the analytical signal, calibration, and common interferences of animal feeds were also discussed. The proposed FI-CL method was successfully applied to the determination of nitrofurans in animal feeds, with excellent recoveries, as the determination is free from interference. The method validation has been compared versus HPLC method for animal feed samples.