Precipitation separation of lead and calcium,strontium, barium from acidic solutions using crown ether and tungstosilicic acid

It was found that lead reacts with 18-crown-6 (L) and tungstosilicic acid (H₄A) in acidic solutions and a compound with low solubility is formed what was confirmed by radiometric titration methods. Coprecipitation of complexion cation of PbL²⁺ with similar complexion cations of calcium, strontium and barium was studied. Formation of low soluble salts was utilized for separation of Pb from Ca, Sr and Ba from 1 mol·dm^–3 HNO₃. The ratio of Pb/Ca, Pb/Sr and Pb/Ba in the precipitation or separation factors S_pb/M undoubted depends on the ratio of the stability constants of lead and metals with 18C6 (_Pb/_M), what can be used for determination of more precise constant stability _M.