Supramolecular-based dispersive liquid-liquid microextraction: A novel sample preparation technique for determination of inorganic species

A new simple and sensitive method has been developed for the determination of trace levels of inorganic species in environmental water samples. It is based on the use of supramolecular-based dispersive liquid-liquid microextraction (SM-DLLME) prior to microsample introduction into FAAS. The ions are micro-extracted with coacervates composed of reverse micelles made from decanoic acid and dispersed in tetrahydrofuran-water mixtures. Cobalt ion was used as a model ion, and 1- (2-pyridylazo)-2-naphthol as the complexing agent. SM-DLLME results from a combination of DLLME with coacervation-based microextraction. It combines the advantages of DLLME with those of preconcentration based on coacervation and reverse micelles. Factors affecting the extraction efficiency of Co and its subsequent determination by FAAS were optimized. Under the optimized conditions and using 5.00 mL sample only, the enhancement factor is 58, the limit of detection is 4.2 mu g L(-1), and the relative standard deviations for 100 mu g L(-1) and 30 mu g L(-1) of Co are 2.1% and 3.8%, respectively (n = 6). The accuracy of the method was confirmed by parallel analyses using the ASTM reference method.