Die pCO2-/pO2-Optode: Eine neue p CO2- bzw. pO2-Meßsonde zur Messung des pCO2 oder pO2 von Gasen und Flüssigkeiten / The pCO2-/pO2-Optode: A New Probe for Measurement of pCO2 or pO2 in Fluids and Gases
2014
Lübbers, D. W. | Opitz, N.
To measure pO₂ or pCO₂ in gases or fluids the fluorescence indicators pyrene butyric acid or β-methylumbelli-feron were used, which were separated from a measuring medium by a gas-permeable membrane. For p CO₂ the pH changes in NaHCO₃ solution were monitored by methyl-umbelliferon. Changes in its fluorescence signal, S, were measured at λ (emission) = 445 nm. Excitation was brought about by light of wavelength λ₁ = 318 nm (fluorescence signal S₁) , and λ₂ = 357 nm (fluorescence signal S₂). Drawing lg(S₂/S₁) against lg(pCO₂-1), one obtains a straight line between a p CO₂ of 10 and 70 Torr. The response time is about 3 to 4 s (90%). For pO₂ , pyrene butyric acid is used (λ (excitation) = 342 nm; λ(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%).
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