KCS

A newly synthesized macrocyclic polyamide was used as an ionophore for the selective determination of monohydrogen phosphate ion. All solid state polyvinyl chloride (PVC) membrane electrode containing ionophore and nitrophenyl octyl ether as plasticizer showed a near-Nernstian slope of 32.0±1.0 mV/decade of activity for monohydrogen phosphate in the concentration range of 1.0x10^-6-1.0x10^-1 M at pH of 7.4. The life time of the electrode was 1 month. The electrode displayed the following selectivity sequence HPO₄^2->SO₄^2->Ac^->NO₃^->ClO₄^->Cl^->I^-, which showed anti-Hofmeister selectivity. The electrode exhibited a high selectivity for monohydrogen phosphate over other anions except SO₄^2-. The electrode was successfully used as an indicator to determine the end point in the potentiometric titration of phosphate against standard barium chloride solution as well as for real sample analysis.