Fast and simple method using DLLME and FAAS for the determination of trace cadmium in honey

A novel method for the determination of trace cadmium in honey is presented. It consists of a preconcentration step based on dispersive liquid-liquid microextraction (DLLME) and measurement by flame AAS. Samples are dissolved in water. A mixture of carbon tetrachloride (extraction solvent) and acetonitrile (dispersion solvent) containing ammoniun pyrrolidine dithiocarbamate (APDC) as complexing agent is injected rapidly into the dissolved sample by means of a syringe pump. After centrifugation, an aliquot of the organic phase is injected in the nebuliser of an atomic absorption spectrometer by means of a lab-made microsampling device. Response (integrated absorbance) was linear with concentrations up to 12 mu g L-1. Precision (s(r)(%)) at the 5 mu g L-1 level was < 3.1%. Detection and quantification limits were 1.6 and 5.5 mu g per 100 g of honey respectively. Six commercial samples were spiked at the 10 mu g per 100 g level and analysed by the proposed method and by electrothermal atomic absorption spectrometry. The results did not differ at the 5% significance level, with recoveries for the DLLME/FAAS method ranging from 82 to 125%. The proposed method requires simple sample preparation and does not use expensive equipment, thus it could be used as screening method for the content of cadmium in honey.