Copper(II)-selective membrane electrodes based on some recently synthesized mixed aza-thioether crowns containing a 1,10-phenanthroline sub-unit.

Three different mixed aza-thioether crowns containing a 1,10-phenanthroline sub-unit were investigated to characterize their abilities as copper(II) ion carriers in PVC-membrane electrodes. The electrode based on L1 exhibited a Nernstian response for Cu(2+) ions over a wide concentration range (2x10(-1) to 1x10(-5) M) with a limit of detection of 8.0x10(-6) M (0.5 p.p.m.). The response time of sensor is 15 s, and the membrane can be used for more than 3 months without observing any deviation. The electrode revealed comparatively good selectivities with respect to many alkali, alkaline earth, transition and heavy metal ions, and could be used in a pH range of 2.5-5.5. It was applied to the direct determination and potentiometric titration of the copper(II) ion.