O2k-Manual: O2k-Calibration
Accurate calibration of the oxygen sensor depends on (1) calibration solutions prepared at known oxygen partial pressures, as achieved in the Oxygraph-2k (O2k) at defined temperature, continuously recorded total gas pressure (barometric pressure), and thermodynamic equilibrium between the gas and aqueous phase; (2) high stability of the signal of the polarographic oxygen sensor (POS), tested for sufficiently long periods of time; (3) linearity of signal output with oxygen pressure, achieved with the POS in the range between oxygen saturation and zero oxygen pressure; and (4) application of accurate oxygen solubilities for aqueous solutions for the conversion of partial oxygen pressure into oxygen concentration (see MiPNet06.03). The standard oxygen calibration procedure is described for O2k high-resolution respirometry with the automatic calibration routine of DatLab 4.
The oxygen sensors are calibrated by a two-point calibration, routinely achieved at air saturation and zero oxygen concentration. Accordingly, static calibration involves the determination of the constant signal of the polarographic oxygen sensor (POS) at 0 % and 100 % air saturation (R0 and R1) under the particular experimental conditions (temperature, signal amplification by electronic gain, stirring speed, medium).
In DatLab, the oxygen signal can be converted at any time during the experiment from the recorded value or raw signal, Rt, to oxygen concentration, cO2,t [mM], or partial pressure, pO2,t, in untis of [kPa] or [mmHg]. If the oxygen solubility of the incubation medium is not known, it may be selected according to general guidelines [Oxygen solubility, see MiPNet06.03]. The calibration for display does not influence the recorded signal on file. However, information on the calibration variables is saved together with the raw data.
Instructions for using the templates are given in the O2k-Manual: Oxygen and pH Calibration. MiPNet12.08 on page 8 (see above):
Excel Template "O2k-Calibration-list. xls" is the template for generating a data base for quality control of instrumental calibration. Trends over time can thus be evaluated, and possible irregularities of sensor performance are quickly recognized for intervention (e.g. POS service).
- "O2k-Calibration-list.xls" [download 128 kb; 2009-04-28]
For downloading, click on the file name and save to C:\DatLab\DLTemplates.
