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Die pCO<sub>2</sub>-/pO<sub>2</sub>-Optode: Eine neue p CO<sub>2</sub>- bzw. pO<sub>2</sub>-Meßsonde zur Messung des pCO<sub>2</sub> oder pO<sub>2</sub> von Gasen und Flüssigkeiten / The pCO<sub>2</sub>-/pO<sub>2</sub>-Optode: A New Probe for Measurement of pCO<sub>2</sub> or pO<sub>2</sub> in Fluids and Gases
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1975
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EngineeringGas SensorPco 2ChemistryPo 2New ProbeChemical EngineeringPhosphorescence ImagingEnvironmental ChemistryOptical DiagnosticsAnalytical ChemistryInstrumentationChemical SensorPhotophysical PropertyBiophysicsResponse TimeChemical MeasurementPhotochemistryAtomic Fluorescence SpectroscopyOptical SensorsElectrochemical Gas SensorNatural SciencesSpectroscopyPhosphorescence
Abstract To measure pO 2 or pCO 2 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 CO 2 the pH changes in NaHCO 3 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 λ 1 = 318 nm (fluorescence signal S 1 ) , and λ 2 = 357 nm (fluorescence signal S 2 ). Drawing lg(S 2 /S 1 ) against lg(pCO 2 -1), one obtains a straight line between a p CO 2 of 10 and 70 Torr. The response time is about 3 to 4 s (90%). For pO 2 , pyrene butyric acid is used (λ (excitation) = 342 nm; λ(emission) = 395 nm). A linear increase in pO 2 between 0 and 300 Torr yields a linear increase in the reciprocal fluorescence signal. The response time is about 3 s (90%).