FLOW-THROUGH TYPE CHLORIDE-ION SELECTIVE OPTODES BASED ON LIPOPHILIC ORGANOMETALLIC CHLORIDE ADDUCTS AND A LIPOPHILIC ANIONIC DYE

Flow-through type fiber-optic chloride ion selective optodes have been developed based on chloride adducts of lipophilic organometallic comp ounds, including a metal: Sn, Ge, Hg or Hf and a lipophilic anionic in dicator dye of the diphenyl amine type. The pellicular-type ODS beads were coated with a lipophilic organic liquid containing the lipophilic organometallic compound as the anion-selective ionophore ligand and L AD-3 as the color changeable indicator dye. The optode system was cons tructed by packing these color changeable ion sensing beads in the flo w-through optical cell (cell volume, 7 mul) having a quartz window att ached directly to the distal end of a bifurcated optical fiber. The op tode based on tricyclohexyltin chloride (TCTCl) exhibited the most sen sitive response to chloride ion among all the sensors using the organo metallic compounds investigated. This optode could detect chloride ion in the concentration ranging from 10(-4) to 1 M at pH 6.5 with a 0.01 M sodium phosphate buffer as the flowing solution by measuring the ab sorbance change in the sensing beads at 516 nm. This optode showed suf ficient selectivity for the determination of chloride ion in normal hu man serum.