Ion-association dispersive liquid–liquid microextraction of ultra-trace amount of gold in water samples using Aliquat 336 prior to inductively coupled plasma atomic emission spectrometry determination

Gold is a rare and noble metal with atomic number of 79. Several techniques including both spectrometric and electrochemical methods are widely used to determine gold level in real samples. As a result of low concentration of gold in environmental samples, sample preparations such as extraction, clean-up, and pre-concentration before instrumental analysis are mandatory. Thus, a pre-treatment method (dispersive liquid–liquid microextraction (DLLME)) for gold pre-concentration and inductively coupled plasma optical emission spectrometry (ICP-OES) determination is proposed. An extraction method employing DLLME and ICP-OES has been developed for rapid separation, pre-concentration, and determination of ultra-trace amount of Au (III). The extraction of the analyte was performed in the presence of a quaternary ammonium cation, N -methyl- N , N , N -trioctylammonium chloride, (Aliquat 336) as an extractant based on ion-association extraction system. 1-Octanol and acetonitrile were used as extraction and disperser solvents, respectively. The variables affecting the extraction conditions were optimized. A calibration curve in the range of 0.3–100 ng mL −1 , the detection limit of 0.09 ng mL −1 , an enrichment factor of 150, and an extraction recovery of 74 % were obtained. The precision (RSD %) of the method was 6 % for five replicates and recoveries of 10 ng mL −1 Au(III). The combined DLLME method with ICP-OES can readily determine Au(III) at trace (μg L −1 ) level using only 10 mL of sample solution (tap, lake, and mining water) without interference by the matrices. This methodology is simple, fast, and low cost which can be used in routine analytical laboratories.