A comparative study of four 20-membered N 2S 4-crown ethers as ionophores for polymeric membrane silver selective electrodes

Abstract

Four 20-membered N 2S 4-monoazathiacrown ethers have been synthesized and explored as neutral ionophores for Ag +-selective electrodes. Potentiometric responses reveal that the flexibility of the ligands has great effect on the selectivity and sensitivity to Ag + ions. The electrode based on ionophore 9,10,20,25-tetrahydro-5 H,12 H-tribenzo[b,n,r][1,7,10,16,4,13]tetrathiadiaza cycloicosine 6,13-(7 H,14 H)-dione ( C) with 2-nitrophenyl octyl ether ( o-NPOE) as solvent in a poly(vinyl chloride) (PVC) membrane matrix shows a measuring range of 1.0 × 10 −6 to 1.0 × 10 −3 mol/L with a Nernstian slope of 54.9 ± 0.3 mV/decade. This electrode has high selectivity for Ag + with negligible interference from many other cations and can be used in a wide pH range of 3.6–9.2.