Use of ionic liquid in simultaneous microextraction procedure for determination of gold and silver by ETAAS

A new and green dispersive liquid-liquid microextraction procedure is proposed for rapid and simultaneous separation and preconcentration of ultra trace amounts of Au(III) and Ag(I) in various media by using N-(4-{4-[(anilinocarbothioyl)amino]benzyl}phenyl)-N-phenylthiourea as chelating agent and 1-hexyl-3-methylimidazolium hexafluorophosphate [Hmim][PF6] as extracting solvent. Then interested elements were determined by electrothermal atomic absorption spectrometry. Various parameters that affect the extraction procedure such as pH, extraction time and temperature, chelating agent concentration and sampling volume on the recovery of the selected ions were investigated. Under optimum conditions, the enhancement factor of 48.7 and 48.3, the precision of +/-4.1 and +/-3.7% and calibration graphs of 0.02-40 and 0.012-14 mu g L-1 for gold and silver were obtained, respectively. The limit of detection and quantification were 4.8 and 15.9 ng L-1 for Au and 2.6 and 8.6 ng L-1 for Ag. The results show that liquid-liquid pretreatment using ionic liquid is a sensitive, rapid, simple and safe method for the simultaneous preconcentration of gold and silver. The method was successfully applied for determination of gold and silver in natural water and hair samples. (C) 2012 Elsevier B.V. All rights reserved.