Coated wire lead(II) selective potentiometric sensor based on 4-tert-butylcalix[6]arene

A coated-wire lead ion-selective electrode (ISE) has been constructed using 5,11,17,23,29,35-hexa-tert-butyl-37,38,39,40,41,42-hexahydroxycalix[6]arene as neutral carrier in a poly(vinyl chloride) matrix. The sensor exhibited a linear Nernstian response over the range 1×10−6 to 1×10−1 M with a slope of 30±1 mV per decade change and a detection limit of 6×10−7 M. The working pH range of the sensor is 1.5–6.0 and it shows good selectivity for Pb(II) ions over other mono-, bi- and trivalent cations. The selectivity coefficients (Kij) were determined for Na(I), K(I), Ag(I), Mg(II), Ca(II), Ba(II), Sr(II), Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Hg(II), Cr(III), Fe(III) and Al(III); the values for these ions being in the range of 10−4–10−2. The sensor was successfully used as an indicator electrode in potentiometric titration of lead ions with EDTA. The ISE was also used for determination of lead in electroplating bath solutions, alloy sample, battery waste samples and effluent waters.