Polymeric ISE for hydrogen sulfite based on bis-urea calix[4]diquinones as neutral lipophilic ionophores

A new PVC membrane electrode for HSO3- anion based on bis-urea calix[4]diquinones I-VI as neutral ionophores is prepared. Of the various membranes prepared, the membrane based on calix[4]diquinone III exhibits a linear stable response over a wide concentration range (6.0x10(-5)-1.0x10(-2)) with a slope of -51.5 mV/decade and a detection limit of 2.2x10(-6) M. With the exception of HSO3- anion, the remainder of the anions responds based on their hydrophobicity. The membrane revealed improved selectivity coefficients for HSO3- over a wide variety of other anions, and the comparable selectivity for the HSO3- selective membranes is iodide anion.