Kerman, Kerman, Iran) and dam water (Chahar Gonbad, Sirjan,
Iran) were selected, and the proposed method was applied to determine
the gold and silver content. A 250.0 mL of water sample was
adjusted to pH 2.0 with nitric acid so as to prevent adsorption of
the metallic ions into the flask walls. Samples were filtered to remove
any suspended material. For preconcentration, the pH of the appropriate
amount of samples was adjusted to ~3 before analyzing by
the described procedure.
2.3.2. Hair
Human hair sample was immersed in acetone for 30 min, washed
by water and then dried. 0.5 g of sample was weighed accurately,
digested by 32.0 mL of a mixture solution of HClO4 and HNO3
(1:8 v/v) at low temperature. The digested solution was dried under
elevated temperature, and then several drops of H2SO4 (1:1 v/v)
were added to the residue. After leaching with water, the residue
was transferred to a 100 mL measuring flask and diluted to the
mark with deionized water. An aliquot of solution after adjusting
the pH were analyzed for Au and Ag by the described procedure [19].