potassium-selective membrane sensor based on two recently synthesized poly(oxyethylene) derivatives

two poly(oxyethylene) derivatives 1.10-bis(2'-benzoic acid)-1,4,7,1-tetradecane (l1) and 1,7-bis(2'-benzoic acid)-1,4,7-trioxaheptane (l2) were used as suitable ionophores for the preparation of potassium-selective pvc-membrane electrodes. the resulting electrodes based on l1 and l2 exhibit linear responses to the activity of k+ ions within the concentration ranges of 3.1´10-5 -2.7´10-2 m and 2.0´10-5-7.3´10-2 m with the slopes of 61.8 and 62.6 v per decade, respectively. the electrodes show relatively fast response times of 25-30 s and can be used for at least 3 months without any considerable divergence in potential. the working ph range of the electrodes is 3-11. the selectivity coefficients of the electrodes for potential interfering cations including alkali, alkaline earth and transition metal ions are reported.