Comparative Study of Lead(II) Selective Poly(vinyl chloride) Membrane Electrodes Based on Podand Derivatives as Ionophores

The two podand chelates based on diethylsulfide, 1,5‐bis(2′‐hydroxy‐4′‐nitrophenoxy)‐3‐thiapentane ( L 1 ) and 1,5‐bis(8′‐oxybenzopyridine)‐3‐thia pentane ( L 2 ), have been synthesized and explored as neutral ionophores for preparing poly(vinyl chloride) based membrane electrodes selective to Pb 2+ . The addition of anionic additives and various plasticizers has been found to substantially improve the performance of the electrode. The best performance was obtained with the electrode No. 1 having a membrane of ionophore ( L 1 ) with the composition PVC: o ‐NPOE:ionophore ( L 1 ):NaTFPB (%w/w) of 33 : 62 : 3 : 2. The electrode exhibits Nernstian response with a slope of 31.57±0.3 mV decade −1 of activity in the concentration range from 2.0×10 −9 to 1.0×10 −1  M Pb 2+ , performs satisfactorily over a wide pH range (1.6–7.0), with a fast response time (5 s).