The modified sorbents with dithizone and zinc dithizonate adsorbed on the silica surface were obtained. The adsorption of heavy metal ions from aqueous solutions onto loaded silicas was studied. Color scales for Ag(I), Hg(II) and Pb(II) visual test detection were worked out. The modified silica gels were established to be applicable to semi-quantitative determination of these metal ions in buttermilk, natural, mineral and waste water.