A new methodology ultrasound assisted cold-induced aggregation microextraction (USA-CIAME) was developed for the determination and extraction of ultra trace levels of Au3+ from aqueous hydrochloric acid solutions by pure ionic liquid (IL), in the absence of chelating agents. The extraction behaviour of metal ions by [Hmim]PF6 was particularly studied. Moreover, the stripping of metal ions from the IL phase was investigated. Au3+ in IL phase can be quantitatively recovered by NaPF6. Recycle testing indicated that IL loss can be avoided by the additon of [Hmim]+ to the initial AuCl4− solutions before extraction and/or using PF6− solutions for stripping. The main factors affecting Au3+ extraction, the amount of IL, the pH of the sample solutions, and the chloride ion concentration on extraction efficiencies were carefully studied. A linear calibration was obtained for 1.5 to 200 μg L−1 of Au3+ and the limit of detection was 0.59 μg L−1. The validation of this method was done by recovery and determination of trace amount of gold in river, sea water and geological samples with satisfactory results.
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