Background correction

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Background correction


Background correction calculates the instrumental (and chemical) background flux per volume of the closed experimental chamber (O2k-Chamber). For oxygen flux, the O2 background correction is calculated as a function of oxygen concentration. If no experimental background test has been performed, the system default values are used, which are a°=-2.0 pmol/(s·ml) for the intercept at zero oxygen concentration, and b°=0.025 for the slope of background flux as a function of oxygen concentration. Applying the background correction expresses fluxes of the sample, which are automatically corrected for instrumental (and chemical) background.

Reference: MiPNet14.06 Instrumental O2 background

MitoPedia O2k and high-resolution respirometry: DatLab 

Oroboros support

O2k-technical support

This information is part of O2k-technical support and open innovation.

O2 slope in the closed and open O2k-Chamber

In an open chamber of the O2k the liquid phase in the chamber (aqueous medium) is in equilibrium with the atmosphere. All oxygen consumed by the polarographic oxygen sensor (POS) is immediately replaced from the atmosphere. The oxygen signal therefore has to be constant and the (negative) time derivative of the oxygen signal, called "O2 slope uncorr." in DatLab, has to be zero. The background corrected oxygen flux is meaningless for the open chamber situation. This is because the background correction at air saturation subtracts the consumption of oxygen by the sensor from the negative slope, when diffusion into and out of the chamber is zero at air saturation. Therefore, the background-corrected oxygen flux in the open chamber at air saturation is shown as a negative value. To avoid this apparent artefact, the "O2 slope uncorr." is selected to be shown while the chamber is open. Only Graph Layouts that display "O2 slope uncorr." are suitable for assessing the stability of the oxygen signal when the chamber is open. Such Layouts are:
  • 01 Calibration show Temp
  • 02 Calibration - Background
The observation of a zero flux with an open chamber is an important performance parameter. It indicates that thermal stability and equilibrium of oxygen between the gas and aqueous phases have been reached. Therefore no experiment should be started before a zero "O2 slope uncorr." has been reached with an open chamber. The suggested criterion for signal stability is a "O2 slope uncorr." between -1 pmol/(s mL) and + 1 pmol/(s mL).