CARBONATE ION-SELECTIVE ELECTRODES WITH TRIFLUOROACETOPHENONE DERIVATIVES IN POTENTIOMETRIC CLINICAL ANALYZER

Properties of six derivatives of 1-trifluoroacetylbenzene: [4-(n-butyl )- (1), 4-(n-hexadecyl)- (2), 4-dodecyIoxy- (3), 4-(n-dodecylsulfonyl) - (4), N,N-dioctyl-4-trifluoroacetylbenzamide (5): octyl-p-trifluoroac etylbenzoate (6)] as neutral carriers for carbonate ion were examined and compared. The sensitivity towards carbonate ion was for (3) pH dep endent. This eliminates (3) from practical applications in clinical an alysis. When measuring CO32- within the physiological range of human b lood using as carriers compounds 1 and 2 the interference of chloride must be taken into account. In the case of carriers 4, 5, 6 this effec t is negligible. Electrodes with membranes containing as carriers 2, 4 , 5 and 6 were tested in an automatic potentiometric clinical analyser Microlyte 6, KONE. To avoid contamination by atmospheric CO2 of three aqueous standards (TES, NaCl, NaHCO3), pH was adjusted by coulomeric generation of H+ or OH- in a system devoid of carbon dioxide. Recovery of HCO3- calculated from measured CO32- and pH, was investigated in a series of aqueous solutions and spiked bovine serum samples. The corr elation between added and recovered concentration of HCO3- was linear with the intercept close to 0 and slope equal to 1 in aqueous solution s for all ligands and in bovine serum samples only in the case of liga nd (2). (C) 1997 Elsevier Science B.V.