Direct electrochemical determination of very low levels of 5-hydroxymethyl furfural in natural honey by cyclic and square wave voltammetric techniques

Abstract

The present study reported the electrochemical determination of 5-hydroxymethylfurfural (HMF) obtained by the degradation of fructose, with a glassy carbon electrode. This study was performed by cyclic voltammetry (CV) and square wave voltammetry (SWV). The aim of this work was to propose a direct and rapid technique to quantify HMF in honey. The effect of scan rate, pH and temperature was evaluated to select the optimum experimental conditions. HMF was irreversibly reduced, thus producing a single cathodic peak at a potential of −1.6 V vsSCE in the presence of Na2SO4 as supporting electrolyte involving a transfer of two electrons. The diffusion coefficient was calculated from convoluted cyclic voltammograms and was found to be 2.23 10−6 cm2 s−1. The voltammetric determination of HMF was carried out under optimum conditions. The calibration curves for the determination of HMF exhibited the good linear responses within the concentration range from 0.15 to 1.26 mg L−1 for CV method and from 0.03 mg L−1 to 0.38 mg L−1 for SWV method. In water, the quantification limits of HMF were about 83.3 10−3 mg L−1 and 7.2 10−3 mg L−1 for CV and SWV, respectively. The SWV technique showed a higher sensitivity and reproducibility in analytical response. In honey solution, the limit of quantification was found to be 0.02 mg L−1. The method was successfully applied to the analysis of HMF in honey and syrup samples containing different concentrations with good recovery values.