Selective Ligandless Cloud Point Extraction of Gold from Wastewater and ore Samples

A selective and sensitive cloud point extraction procedure for the preconcentration of trace amounts of gold prior to their determination by flame atomic absorption spectrometry has been developed. The cloud point extraction method is based on the formation AuI3 and then entrapped in non-ionic surfactant Triton X-114. The main factors affecting cloud point extraction efficiency, such as pH of sample solution, concentration of iodide ion and Triton X-114, equilibration temperature and time, were investigated in detail. Under the optimized conditions, calibration curves were constructed for the determination of gold according to the general procedure. Linearity was maintained between 3.0 ng mL-1 to 1.5 μg mL-1. Detection limits based on three times the standard deviation of the blank divided by the slope of analytical curve (3Sbm) for Au (III) ion was 1.3 ng mL1. Eight replicate determination of a solution of 0.1 μg mL-1 gold gave a relative standard deviation 1.9%. The high efficiency of cloud point extraction to carry out the determination of analyte in complex matrices was demonstrated. The proposed method has been applied for determination of trace amount of gold in certified reference material, Silica ore and wastewater samples with satisfactory results.