Mercury chloride (HgCl2), 1-octanol (C8H18O), potassium iodide (KI), hydrochloric acid (HCl) and sulfuric acid (H2SO4) were purchased from Merck (Darmstadt, Germany). Hydrogen tetrachloroaurate (III) (HAuCl4) was purchased from Acros (Geel,Belgium). Di-(2-ethylhexyl) phosphate (DEHP) was purchased from Fluka (Buchs, Switzerland). All chemicals were
analytical grade and were used without further purification. All the working solutions were prepared using de-ionized water purified by Milli-Q filtration system (Millipore, USA).