A New Dispersive Liquid-Liquid Microextraction Method Followed by Direct GF-AAS Determination Optimized with Experimental Design and Response Surface Methodology for Determination of Ag(I) in Water Samples

In this research, a rapid, reliable and selective dispersive liquid-liquid microextraction (DLLME) followed by direct injection of microdroplet to graphite furnace atomic absorption spectrometry (GF-AAS) method for the determination of ultra-trace amounts of Ag(I) was developed. Effect of the important experimental parameters on the extraction efficiency of Ag(I) was investigated using response surface methodology (RSM) by performing a central composite design (CCD). A newly synthesized Calixarene (mesotetraspirocyclohexylcalix[۴]pyrrole, TSCC۴P) was utilized as the chelating agent. The optimal experimental condition was obtained as sample volume: ۵ ml, dispersive solvent type: methanol, dispersive solvent volume: ۷۱۵ μl, extracting solvent: ۱,۲-dichlorobenzene, volume of extracting solvent: ۲۵ µl, amount of TSCC۴P: ۱۲۷.۱ µg, and pH of sample solution: ۶.۵. Under the optimum conditions Ag(I) ions were extracted into a fine sedimented microdroplet, which ۱۰ µl of it was directly injected into GF-AAS system. The calibration graph was linear over the range of ۰.۱-۱۰.۰ ng ml-۱ with a detection limit (S/N = ۳) of ۰.۰۲ ng ml-۱. The relative standard deviation (RSD%) for ten replicated determinations of ۱۰ ng ml-۱ Ag(I) was ۳.۱%. The enrichment factor and extraction recovery were found to be ۲۹۲ and ۹۶%, respectively. The proposed DLLME-GF-AAS method was successfully applied to the extraction and determination of Ag(I) ions in different real water samples.

Keywords:

Silver , Dispersive liquid-liquid microextraction , GF-AAS , Experimental Design , Response Surface Methodology