Five grams of a powdered ore sample (Dehdasht, Iran) was
accurately weighed into a 50 mL glass beaker, to which 25 mL of
concentrated nitric acid was added. The sample was gently heated
on a sand bath at a low boiling temperature until dense white
fumes disappeared. After cooling, 5 mL of 5 mol L1 nitric acid
and 10 mL of water were added into the beaker to dissolve the
analyte. The solution was filtered into a 50 mL volumetric flask,
and after washing the filter paper with water, the solution was
diluted to the mark