A new sodium ion selective electrode based on a novel silacrown ether

Abstract

The synthesis of 1-methyl-1-vinyl-14-crown-5 ( III) by the reaction of (H 2C CH)MeSi(OEt) 2 with HO(CH 2CH 2O) 4H in presence of catalytic amounts of NaOMe is described. PVC-based membranes of III as ionophore with potassium tetrakis( p-chlorophenyl)borate (KT p ClPB) as anion excluder and dioctylphthalate (DOP), diphenylether (DPE), dibutylamine (DBA) and dibutylphthalate (DBP) as plasticizing solvent mediators were prepared and investigated as Na +-selective electrode. The response of the electrode was linear with a Nernstian slope of 55.0 mV/decade over an Na + ion concentration range of 3.16 × 10 −6 to 1.0 × 10 −1 M and a detection limit of 2.81 × 10 −6 M. The response time to achieve a 95% steady potential for Na + concentrations ranging from 1.0 × 10 −1 to 1.0 × 10 −7 M was between 5 and 15 s, and the electrode is suitable for use within the pH range of 6.5–9.5. The selectivity relative to alkali, alkaline earth and transition heavy metal ions is good. The selectivity coefficient towards potassium has been calculated to log ⁡ K N a + , K + Pot = − 3.35 by utilizing the Fixed Interference Method. The electrode could be used for at least 45 days without considerable alteration in its potential. The effect of non-ionic surfactants (Brij 58, Brij 78, Triton X-405 and Tween 20) on the potentiometric property of the sodium selective membrane was also studied. The electrode also shows better working concentration range and slope in comparison to the other Na + selective electrodes reported in literature.