Ionic liquid-based modified cold-induced aggregation microextraction (M-CIAME) as a novel solvent extraction method for determination of gold in saline solutions

Modified-cold-induced aggregation microextraction (M-CIAME) was used for determination of gold in saline solutions. It is robust against the much higher concentration of salt (up to 40%). In this method sodium hexafluorophosphate (NaPF6) was added to the sample solution containing Au-TMK complex and a very small amount of 1-hexyl-3-methylimidazolium tetrafluoroborate [Hmim][BF4]. Afterward the solution was cooled in an ice bath and a cloudy solution was formed. After centrifuging, the extractant phase was analyzed using a spectrophotometric detection method. Under the optimum conditions, the limit of detection (LOD) was 0.7 ng mL−1 and the relative standard deviation (RSD) was 1.65% for 50 ng mL−1 gold. The method was applied for the determination of trace amount of Au in mineral and seawater with satisfactory results.