Potentiometric ion determinations using enhanced selectivity asymmetric ion-selective membrane electrodes

摘要

An ion selective electrode (4) employing an asymmetric membrane for the potentiometric determination of ions, e.g. carbonate in biological samples is disclosed. The asymmectric membrane comprises (i) an ion selective layer (8) containing an ion selective agent and a plasticizing agent and (ii) a sample contacting hydrophilic layer (6) fused to the ion selective layer. In a preferred embodiment for determining carbonate, a cellulose triacetate (CTA) hydrophilic layer with free hydroxyl groups is fused to a cellulose triacetate ion selective layer containing trifluoroacetyl-p-butylbenzene (TFABB) as ionophore, tridodecylmethylammonium bromide (TDMAC) as ion-complexing agent, and bis(2-ethylhexyl)adipate (DOA) as plasticizer. The electrode has the advantage of being less sensitive to interferents such as salicylate, gentisate, perchlorate etc.