Ligandless, ion pair-based and ultrasound assisted emulsification solidified floating organic drop microextraction for simultaneous preconcentration of ultra-trace amounts of gold and thallium and determination by GFAAS

In the present work, a new, simple and efficient method for simultaneous preconcentration of ultra-trace amounts of gold and thallium is developed using an ion pair based-ultrasound assisted emulsification-solidified floating organic drop microextraction procedure before graphite furnace atomic absorption spectrometry determination. This methodology was used to preconcentrate the ion pairs formed between AuCl4− and TlCl4− and [C23H42]N+ in a microliter-range volume of 1-undecanol. Several factors affecting the microextraction efficiency, such as HCl volume, type and volume of extraction solvent, sonication time, sample volume, temperature, ionic strength and [C23H42]NCl volume were investigated and optimized. Under the optimized conditions, the enrichment factor of 441 and 443 and calibration graphs of 2.2–89 and 22.2–667 ng L−1 for gold and thallium were obtained, respectively. The intra- and inter-day precision of ±4.4 and ±4.9% for Au and ±4.8 and ±5.4% for Tl were obtained. The detection limit was 0.66 ng L−1 for Au and 4.67 ng L−1 for Tl. The results show that the liquid–liquid pretreatment using ion pair forming, is sensitive, rapid, simple and safe method for the simultaneous preconcentration of gold and thallium. The method was successfully applied for determination of gold and thallium in natural water and hair samples.

► No previous paper report on use of IP-USAE-SFODME for preconcentration of Au and Tl.
► IP-USAE-SFODME is a “Green method” for simultaneous preconcentration of Au and Tl.
► Under the optimum conditions Au and Tl were enriched 441 and 443 fold, respectively.
► The procedure is simple, rapid and safe and has high tolerance limit to interferences.