How does temperature affect the oxygen measurement?

Like all physical parameters the fluorescence decay time and the Stern-Volmer quenching constant (= collision frequency) are dependent on temperature. The temperature behavior of these parameters is known and compensated. Beside this, the solubility of oxygen in water is temperature-dependent and can be described using the Bunsen absorption coefficient α(θ) and the oxygen partial pressure p(O2). With increasing temperature the solubility of oxygen in water decreases.

cS(p,θ) = [p(O2) - pW(T) / pN] α(θ)

cS(p,θ): temperature-dependent solubility of oxygen in water, given in (cm3(O2)/cm3)

p(O2): oxygen parital pressure

pN: standard pressure

α(θ): Bunsen absorption coefficient, given in (cm3 (O2)/cm3)

The following table gives oxygen solubilities in mg/L for temperature intervals of 0.1°C from 0 - 40 °C. The calculated value for cS at a temperature of 20.0 °C agrees with the tabulated value of 9.08 mg/L.

Example: cS (20.0 °C) = 9.08 mg/L


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