Copper determination in beer by flame atomic absorption spectrometry after extraction and preconcentration by dispersive liquid–liquid microextraction

Abstract

In this work, an extraction and preconcentration method based on dispersive liquid–liquid microextraction (DLLME) for Cu determination in beer by flame atomic absorption spectrometry (FAAS) was developed. The main parameters that influence the extraction efficiency such as the type and volume of extraction (100 µL CCl4) and disperser (not used) solvents, sample volume (5 mL), pH (no adjustment required) and concentration (2 %, m/v) of sodium diethyldithiocarbamate as chelating agent were studied. The accuracy was evaluated by results comparison with those obtained by microwave-assisted digestion and Cu determination by inductively coupled plasma mass spectrometry and inductively coupled plasma optical emission spectroscopy, as well as by recovery tests. The limits of detection and quantification for Cu determination by the proposed DLLME/FAAS method were 3.2 and 9.1 µg/L, respectively. After method optimization, seven beer samples were analyzed and Cu concentration ranged from 20.6 to 58.8 µg/L. In addition, the preconcentration factor for the DLLME procedure was 50 times and the relative standard deviation (RSD) ranged from 3 to 16 %.