PVC Membrane Lithium Ion Chemical Sensors Based On Neutral Ionophore

Plasticized PVC membrane lithium-ion chemical sensors based on neutral ionophore ETH 1810 were prepared by the optimized membrane composition . The electrode membrane solution containing 1.0% ETH 1810 0.2% KTpC1PB.. 33.0% PVC and 66.0% 2-NPOE was obtained. The slope of the electrode was 56.OmV/dec, with the linear range of 3.2xl0.0x10molIL and the detection limit of 1.6x105 moIIL Li . It can use the electrode to assay Li~ in blood within the clinically relevant concentration range and in aqueous solution . Relative standard deviation (RSD.) of determination less than 4% , recoveries were in 98?07% and 93-402% respectively, The electrode showed moderate selectivity for Li over Na and K , their selectivities were 5.Ox 10 and 3.2x 10 respectively .The other characteristics of the electrode were satisfactory basically. Because of the overlap between the fluorescent emission spectrum of 5,10,15,20-tetraphenylporphine (TPP) and the absorption spectrum of ETH5294 , in this paper , a kind of optical chemical sensors of fluorescence enhancement for lithium ions were developed on the basis of ion-exchange sensing scheme . The fluorescent agent TPP was incorporated in the plasticized PVC membrane containing the lipophilic pH-indicator ETH5294 and lithium selective neutral ionophore ETH 1810 ... anionic site KTpC1PB . Fluorescence varied as a function of the varying absorption of the pH-indicator ETH5294 which in turn was modulated by the lithium ion concentration through inner-filter effect of fluorescence. The sensor showed better selectivity to divalent alkaline-earth metal ions and better short-term stability. reversibility. It can detect 5.0x10-.5 molIL Li in the solution with the detection limit of 5 .Ox10 molIL within about 1mm...