POTASSIUM ION-SELECTIVE OPTODES BASED ON THE CALIX[6]ARENE HEXAESTER AND APPLICATION IN HUMAN SERUM ASSAY

Plasticized PVC membranes incorporating the hexaester of calix[6]arene , potassium tetrakis(4-chlorophenyl) borate and a neutral H+-selective chromo-ionophore (ETH 5294) have been used as reversible sensing devi ces for optical determination of potassium ion in pi-I-buffer solution s. At pH 9.0, the absorbance response of the optode shows a good corre lation with the theoretically derived formula in the range from 1 x 10 (-6) to 1 x 10(-2) mol l(-1) potassium ion, Typical response times (t( 95)) in the samples are 3 min, the relative standard deviation for rep eated measurements being within 0.5%, The selectivity of this potassiu m-selective membrane allows its application for the reversible optical detection of potassium concentration in human serum samples.