Ultra-Trace Determination of Copper and Silver in Environmental Samples by Using Ionic Liquid-Based Single Drop Microextraction-Electrothermal Atomic Absorption Spectrometry
A sensitive, selective and effective ionic liquid-based single drop microextraction technique was developed by using ionic liquid, 1-hexyl-3-methylimidazolium hexafluorophosphate, C6MIMPF6, coupled with electrothermal atomic absorption spectrometry (ETAAS) for the determination of copper and silver in environmental samples. Dithizone was used as chelating agent. Several factors that influence the microextraction efficiency and ETAAS signal, such as pH, dithizone concentration, extraction time, amounts of ionic liquid, stirring rate, pyrolysis and atomization temperature were investigated and the microextraction conditions were established. In the optimum experimental conditions, the detection limits (3 s) of the method were 4 and 8 ng L -1 and corresponding relative standard deviations (0.1 μg L -1 , n = 6) were 4.2% and 4.8% for Ag and Cu, respectively. The developed method was validated by analysis of a certified reference material and applied to the determination of silver and copper.