A new setup of flow injection-diode array detection-laser induced fluorescence spectrophotometry for simultaneous determination of copper and iron in food samples

Abstract

A new setup for collection and detection of fluorescence spectrum using a double-frequency Nd-YAG laser as incident light source and coupled with multichannel CCD (charge coupled device) detector and flow injection system was described in this paper. The parameters of the setup were optimized. Fluorescence spectra are measured in the range of 350 nm ~ 700 nm with the wavelength resolution of 0.3 nm and spectral response sensitivity of detector is 0.1 LX. High S/N ratio fluorescence spectrum of Rhodamine B (RhB) solution was measured and the detection limit is 10-9 mol L-1. The setup has been applied to the simultaneous determination of Cu and Fe in food samples. The determination is based on the fluorescence quenching reaction owing to catalytic effects of the metallic ions on the oxidation reaction of RhB and H2O2. The fluorescence spectra of RhB are collected by CCD diode array detector and the overlapping spectra are processed using artificial neural networks (ANN) algorithm. The experimental variables were optimized and the proposed method is validated on determination of Cu and Fe in a wheat reference material and the food samples. The determination results of samples are in good agreement between the proposed method and Atomic Absorption Spectrophotometry (AAS). The average spiked recoveries are 93.3% ~ 95.8% for Cu and 93.4% ~ 100.2% for Fe with relative standard deviation of 0.6% ~ 7.5%.