Single drop based-liquid phase microextraction using ionic liquid as extractor solvent for extraction and preconcentration of copper and silver from food and water samples prior to determination by electrothermal atomic absorption spectrometry

A new single drop micro-extraction method based on ionic liquids was developed for the preconcentration of ultra-traces of silver and copper prior to its determination by electro-thermal atomic absorption spectrometry (ETAAS). An 8-μL drop of ionic liquid, 1-hexyl-3 methylimidazolium hexafluorophosphate, [C6MIM][PF6], was used for the extraction of silver and copper ions as dithizone complex. Important variables affecting microextraction efficiency and ETAAS signal, such as pyrolysis and atomization temperature, dithizone concentration, extraction time, drop volume and stirring rate were investigated and optimized. Under the optimum experimental conditions, the detection limits (3 s) of the method were 4 and 8 ng L-1, for Ag and Cu, respectively and corresponding relative standard deviations (0.1 μg L-1, n = 6) were 4.2% and 4.8%. The developed method was successfully applied to the determination of copper and silver in food and water samples.