Gallium Selective PVC Membrane Electrodes Based on Crown Ethers

Gallium selective electrodes based on 12-crown-4 (12C4) and benzo-15-crown-5 (B15C5) and plasticizers dioctyl phenyl phosphonate (DOPP), di butyl phosphate (DBP), dibutyl phthalatc (DBPH) in PVC matrix membranes are constructed. Specificproperties of the electrodes are studied including calibration curve, slope, dctcction limit, concentration range, response time and life time a.s well as the effect of pH on electrode response. Interference for Li1 Mg2, /n2~, Al3 + , Cr3~ on electrode response have been also investigated. The polymeric liquid membrane electrode based on 12C4 using DBPIT plasticizer exhibits the best over all performances as a gallium selective elec:rodc over a wide concentration range (1 .Ox 105 - 3.3x 102 M) with Ncmcsiian slope (20mV/decadc). It has a relatively fast response time excellent detection limit (TxlO ^M) and good curability (about 2 months). The elecLrode revealed a good selectivity for GaJ over a variety of other metal ions and could be used in a pH range of 3.0-5.0. It was used as an indicator electrode in potentiometric titration of gallium ions.