[The pCO2-/pO2-optode: a new probe for measurement of pCO2 or pO in fluids and gases (authors transl)].

To measure pO2 or pCO2 in gases or fluids the fluorescence indicators pyrene butyric acid or beta-methylumbelliferon were used, which were separated from a measuring medium by a gas-permeable membrane. For pCO2 the pH changes in NaHCO3 solution were monitored by methylumbelliferon. Changes in its fluorescence signal, S, were measured at lambda (emmission) = 445 nm. Excitation was brought about by light of wavelength lambda1 = 318 nm (fluorescence signal S1), and lambda2 - 357 nm fluorescence signal S2). Drawing lg(S2/S1) against lg(pCO2-1), one obtains a straight line between a pCO2 of 10 and 70 Torr. The response time is about 3 to 4s (90%). For pO2, pyrene butyric acid is used (lambda(excitation) = 342 nm; lambda(emission) =395 nm). A linear increase in pO2 between 0 and 300 Torr yields a linear increase in the reciprocal fluorescence signal. The response time is about 3 s (90%).