Preconcentration procedure using vortex agitator system for determination of trace levels of cadmium by flame atomic absorption spectrometry

Abstract

A simple and rapid vortex-assisted ionic liquid based liquid-liquid microextraction (VALLME) procedure was used for the determination of trace amounts of cadmium by flame atomic absorption spectrometry (FAAS). Ionic liquid (IL), 1-hexyl-3-methylimidazolium hexafluorophosphate ([Hmim][PF6]), was used as an extractant solvent. Cd2+ was complexed with ammonium pyrrolidinedithiocarbamate (APDC) and then entered into the fine IL droplets by the assistance of vortex agitator system. Some effective factors that influence the extraction efficiency such as pH, ligand concentration, amount of ionic liquid, extraction time and ionic strength effect were completely investigated and optimized. Under the optimum conditions, the limit of detection (LOD) was 1.1 ng mL-1. The relative standard deviation (RSD) was 4.3% for 20 ng mL-1 of cadmium (n = 10), and the calibration graph using the preconcentration method was linear from 5 to 150 μg L-1, with a correlation coefficient of 0.998. The proposed method was successfully applied for determination of cadmium in water samples and spinach leaves. © 2012 Sociedade Brasileira de Química.