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

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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[4]pyrrole, TSCC4P) was utilized as the chelating agent. The optimal experimental condition was obtained as sample volume: 5 ml, dispersive solvent type: methanol, dispersive solvent volume: 715 μl, extracting solvent: 1,2-dichlorobenzene, volume of extracting solvent: 25 µl, amount of TSCC4P: 127.1 µg, and pH of sample solution: 6.5. Under the optimum conditions Ag(I) ions were extracted into a fine sedimented microdroplet, which 10 µl of it was directly injected into GF-AAS system. The calibration graph was linear over the range of 0.1-10.0 ng ml-1 with a detection limit (S/N = 3) of 0.02 ng ml-1. The relative standard deviation (RSD%) for ten replicated determinations of 10 ng ml-1 Ag(I) was 3.1%. The enrichment factor and extraction recovery were found to be 292 and 96%, respectively. The proposed DLLME-GF-AAS method was successfully applied to the extraction and determination of Ag(I) ions in different real water samples.