Supramolecular-Based Ultrasonic-Assisted Dispersion Solidification Liquid-Liquid Microextraction of Copper and Cobalt Prior to Their Flame Atomic Absorption Spectrometry Determination.

In the present work, a simple, efficient, and environmentally friendly method was proposed for the simultaneous preconcentration and determination of minute quantities of copper and cobalt in water samples and serum by a supramolecular-based ultrasonic-assisted dispersion solidification liquid-liquid microextraction (DSLLME) procedure coupled with flame atomic absorption spectrometry. The procedure is based on the DSLLME of copper and cobalt with decanoic acid-tetrahydrofuran supramolecular solvent (SUPRAS) in the presence of sodium diethyldithiocarbamate, as the complexing agent. SUPRAS is a nanostructured liquid generated from amphiphiles through a sequential self-assembly process occurring on two scales, molecular and nano. Several variables that affect the extraction efficiency-including pH, concentration of complexing agent, volume of the extraction and dispersive solvents (volume of SUPRAS), sonication time, and ionic strength-were investigated and optimized. The method provided enrichment factors of 23.31 and 22.38 for copper and cobalt, respectively. The preconcentration factor for the two analytes was 20.00. Calibration plots were linear in the range of 5.00-700.00 ng/mL for copper and 5.00-500.00 ng/mL for cobalt, with correlations of determination of 0.9973 and 0.9981. The precision of the method were expressed as RSDs for six replicate measurements and LODs and found to be ±4.10 and ±2.30% for copper and 2.90 and 3.50 ng/mL for cobalt. The proposed method was successfully applied to the simultaneous determination of trace copper and cobalt in real water samples and serum with satisfactory results.