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

Sixto, Alexandra, Mollo, Alicia, Knochen, Moisés
Subtropical plant science 2019 v.82 pp. 103229
absorbance, acetonitrile, atomic absorption spectrometry, cadmium, carbon tetrachloride, centrifugation, equipment, honey, liquid-phase microextraction, screening, solvents
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 μg L−1. Precision (sr(%)) at the 5 μg L−1 level was < 3.1%. Detection and quantification limits were 1.6 and 5.5 μg per 100 g of honey respectively. Six commercial samples were spiked at the 10 μg 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.