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.