O2 background correction - DatLab |
MitoPedia O2k and high-resolution respirometry:
O2k-Open Support
Last update: 2024-10-09
Description
DatLab 8: Open the O2 background correction window to apply the instrumental O2 background values.
DatLab 7 : Flux / Slope
Abbreviation: CTRL+B
Reference: MitoPedia: DatLab
In an experimentally closed chamber, external fluxes due to diffusion or convection into or out of the chamber are minimized, ideally to zero. Unavoidable external fluxes are corrected for, as there are side reactions due to the measuring system, such as oxygen consumption by the oxygen sensor or chemical background effects due to autoxidation of chemical components added to the medium. These external fluxes and side reactions of the experimental system are lumped together in the background flux, JΒ°V,X. A Instrumental background oxygen flux is applied to the total slope, to obtain the metabolic flux, JV,X, describing the experimental reaction under investigation:
Eq(2a): JV,X = dcX/dt Β· Ξ½X-1 Β· SF - JΒ°V,X | Units: [pmol/(sΒ·mL)]
JΒ°V,O2 is the volume-specific background oxygen flux.
Apply the instrumental O2 background correction
In order to apply the instrumental O2 background correction, select Active file as βSource of O2 backgroundβ in the O2 background correction window. The JΒ° marks previously set on the O2 slope neg. plot (Select marks) will be used to calculate the equation of the regression line. If the linearity, intercept (aΒ°) and slope (bΒ°) values are acceptable the background correction can be applied (Apply). If this is done while DatLab is connected to the O2k, the information will be saved for the next experimental runs. Instrumental standard layouts (01 to 03) display the O2 slope negative, which is not background corrected, while sample-specific flux or flow, or flux control ratios are automatically background corrected (standard layouts 04 to 07).
Background correction is especially critical when performing measurements in a high oxygen regime or using samples with a low respiratory flux or flow.
Instrumental background in instrumental and experimental DatLab files
- Instrumental run and DatLab connected: If instrumental background marks ( JΒ°1 to JΒ°4) are set and background correction parameters are applied in the βO2 background correctionβ window while DatLab is connected to the O2k during an instrumental run (Active file), a pop up message will ask the user if this should be the default instrumental background correction for the sensor. If yes is selected, the background correction parameters are automatically transferred to next experimental DatLab files. Therefore, when a new DatLab file is recorded any time later, the latest background correction parameters are automatically applied in the new DatLab file β independent of maintaining the O2k in operation or switching it off, and independent of maintaining DatLab active or re-opening it after exit.
- Importing of background parameters from file: Instrumental O2 background parameters can also be imported from a DatLab file previously evaluated with the instrumental O2 background test. This can be done by selecting Background file as source of O2 background, and choosing the desired instrumental background file by clicking on the folder icon. An error message will be displayed if the sensor number of the select file does not match the one of the current file. Left click on Apply.
- Inserting background parameters manually: Instrumental O2 background parameters aΒ° and bΒ° can be also edited manually by selecting Manual as source of O2 background and entering the desired values. Left click on Apply.
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