ANION-SELECTIVE LIQUID-POLYMER OPTODES WITH FLUORESCENT PH CHROMOIONOPHORES, TUNABLE DYNAMIC-RANGE AND DIFFUSION-ENHANCED LIFETIMES

The present work demonstrates the ability to extend coextraction based anion optodes into the fluorescence regime for the purpose of miniatu rization. These optodes utilize standard ion-selective electrode ionop hores with universal pH chromoionophores that have been selected for t heir fluorescence efficiency, photo-stability and pK(a) based tunabili ty of the optimal activity range. The miniaturization of the photo-exc itation zone enhances the optode lifetime, due to fast diffusion of un bleached chromoionophores into this zone. Specifically, we provide her e examples of charged and neutral-carrier ionophore based fluorescent optodes, one highly selective for nitrite and the other selective for thiocyanate. The ability to tune the dynamic range of the nitrite-sele ctive optode is also demonstrated.