LUMINESCENCE DECAY TIME-BASED DETERMINATION OF POTASSIUM-IONS

A luminescence decay time-based potassium ion sensor is presented whic h applies the ion-exchange principle. The bulk membrane consists of va linomycin, plasticized PVC, and the ruthenium(II) tris-4,4'-diphenyl-2 ,2'-bipyridyl bromothymol blue ion pair [Ru(dibipy)(3)](BTB)(2) as a p roton donor. The efficacy of radiationless energy transfer from the do nor (the ruthenium complex) to the acceptor (BTB) is mediated by the p otassium ion concentration. The concentration of potassium ions can be calculated from either luminescence intensity or decay time. At pH 8. 7, the working function ranges from 1 to 100 mM KCl.