A study of calcium ion-selective PVC membrane electrode based on neutral carrier N,n,n’,n’-tetracyclo-3-oxapetanediamide

Summary A calcium ion-selective PVC membrane electrode based on neutral carrier n,n,n’,n’-tetracyclohexyl-3-oxapetanediamide, using di-(2-ethylhexyl) phthalate as the plasticizer and potassium tetrakis (4-chlorophenyl) borate as the additive is reported in this paper. The ion selective membrane consists of 1 wt % of the Ca²⁺ selective ligand, 65 wt % of the plasticizer, 1 wt % of the additive and 33 wt % of poly (vinyl chloride) powder. The electrode has the linear response range of 2.0 × 10^™7 —10^™1 mol/L with the Nernstian slope of 28 mV/decade at 25 °C and the detection limit of 2.0 × 10^™8 mol/L. The response time of the calcium ion-selective electrode is 4s as the concentration of calcium ion is rapidly shifted from 10^™5 to 10^™4 mol/L. The potential stability and reproducibility are good. The free calcium in blood serum was determined by the calcium ion-selective electrode with satisfactory results.