The color scale for lead ions detection was
prepared by Pb(II) adsorption onto 0.02 g of
H2Dz-SG from 10 ml of 1 mmol l1 sodium
thiosulfate solution, buffered to pH 8.5 with ammonia
buffer solution, containing 0, 5, 10, 20, 40,
and 100 mg of Pb(II) for 30 min. The sorbents
were separated, washed with 5 ml of 1.0 mmol l1
sodium thiosulfate solution and colored by 40 ml
of PAR aqueous solution. The color changing was
yellow:orange–red.
3.6.3. The color scale for Hg(II) 6isual test