Feasibility of dispersive liquid-liquid microextraction for extraction and preconcentration of Cu and Fe in red and white wine and determination by flame atomic absorption spectrometry

A method for extraction and preconcentration of Cu and Fe in red and white wines using dispersive liquid liquid microextraction (DLLME) and determination by flame atomic absorption spectrometry (F AAS) was developed. Extraction was performed using sodium diethyldithiocarbamate as chelating agent and a mixture of 40 mu l. of 1,2-dichlorobenzene (extraction solvent) and 900 mu L, of methanol (dispersive solvent). Some parameters that influencing the extraction efficiency such as pH (2 to 5), concentration of chelating agent (0 to 2%), effect of salt addition (0 to 10%), number of washing steps (1 to 4) and centrifugation time (0 to 15 min) were studied. Accuracy was evaluated after microwave-assisted digestion in closed vessels and analytes were determined by inductively coupled plasma optical emission spectrometry. Agreement with the proposed method ranged from 91 to 110 and from 89 to 113% for Cu and Fe, respectively. Calibration of F AAS instrument was performed using analyte addition method and limits of detection were 6.3 and 2.4 mu g L-1 for Cu and Fe, respectively. The proposed method was applied for the determination of Cu and Fe in five samples of red wine and three samples of white wine, with concentration ranging from 21 to 178 mu g L-1 and from 1.38 to 3.74 mg L-1 respectively. (C) 2014 Elsevier B.V. All rights reserved.