Popis: |
We report the potentiometric responses towards lead ions of liquid membrane electrodes containing 1,4-bis[2-(3,4,5-trimethoxyphenyl)ethenyl]benzene ( 1 ),2,5-dimethoxy-1,4-bis[2-(3,4,5-trimethoxyphenyl)ethenyl]benzene ( 2 ),1,4-bis[2-(3,4,5-trimethoxyphenyl)ethyl]benzene ( 3 ) and 2,5-dimethoxy-1,4-bis[2-(3,4,5-trimethoxyphenyl)ethyl]benzene ( 4 ). All ligands strongly respond to lead ions in the activity range 10 −6 –10 −3 M and three show high selectivity against common interfering mono- and doubly charged cations. The new ligands demonstrate low affinity for protonation. Addition of 1 mol% of potassium tetrakis( p -chlorophenyl)borate as a lipophilic anionic salt significantly increases the selectivity of ligands 2 , 3 and 4 . The ligands show potential as sensory elements of liquid membrane electrodes destined for determination of lead ions. |