Supramolecular-based dispersive liquid-liquid microextraction: determination of cadmium in water and vegetable samples

A new simple, sensitive and cost effective method has been proposed for rapid determination of trace quantities of cadmium in vegetable samples, using supramolecular-based dispersive liquid-liquid microextraction (SM-DLLME) prior to its microsample introduction-flame atomic absorption spectrometry (FAAS). This method is based on extraction of cadmium-ammonium pyrrolidinedithiocarbamate (APDC) with coacervates made up of decanoic acid reverse micelles dispersed in tetrahydrofuran (THF)-water. Several important factors influencing the extraction efficiency of cadmium and its subsequent determination were investigated and optimized. Under the optimized conditions and preconcentration of only 5.00 mL of sample, the enhancement factor was 22, limit of detection (LOD) was 0.3 mu g L(-1) and relative standard deviations (RSDs) for 100 mu g L(-1) and 30 mu g L(-1) of cadmium in vegetable samples were 2.5% and 4.2%, respectively (n = 6). The accuracy of the method was confirmed by parallel analyses with the reference method (ASTM D 3557-90).