High signal at zero oxygen

MitoPedia O2k and high-resolution respirometry: O2k-Open Support

Description

A high signal at zero oxygen may be observed during zero calibration (R0). First, check the quality of the dithionite solution. The following instructions show how to distinguish between a defective sensor head and an electrical leak current.

Reference: Zero calibration, OroboPOS-Connector

Leak current test

O2k-series J and XB

Unplug the SmartPOS from the O2k-main unit.
Switch on the O2k and start DatLab.
Record the signal for 10 min.
Remove the membrane from the SmartPOS and wash the cathode and anode with distilled water.
Connect the SmartPOS to the O2k-main unit. Set an event in DatLab called "SmartPOS".
Record the signal for 10 min.
Send us the file.

O2k-series D-I and XA

Unscrew the POS from the POS-Connector and unplug the POS-Connector from the O2k-main unit.
Switch on the O2k and start DatLab.
Record the signal for 10 min.
Connect the POS-Connector to the O2k-main unit without the POS. Set an event in DatLab called "POS-Connector".
Record the signal for 10 min.
Remove the membrane from the POS and wash the cathode and anode with distilled water.
Screw the POS to the POS-Connector. Set an event in DatLab called "POS".
Record the signal for 10 min.
Send us the file.

O2k-series A-C

Remove the POS but keep the POS-Connector connected to the main unit. Plugging or unplugging of the POS-Connector while the main unit is switched on could damage the POS-Connector of O2k-series A-C.
Record the signal for 10 min.
Remove the membrane from the POS and wash the cathode and anode with distilled water.
Screw the POS to the POS-Connector. Set an event in DatLab called "POS".
Record the signal for 10 min.
Send us the file.

References

[1] Cleaning the electrical connections

[2] MiPNet19.18B POS-service

[3] MiPNet06.03 POS-calibration-SOP

[4] MiPNet14.06 Instrumental O2 background

Example

First, the OroboPOS-Connector and the POS were disassembled and disconnected from the main unit. Second, the OroboPOS-Connector was connected to the O2k-Main unit without the OroboPOS. Third, the OroboPOS was connected to the OroboPOS-Connector without membranes. After each step, the O₂ raw signal [V] was recorded for 10 min. The marks were set to the O₂ raw signal [V] to evaluate the zero current.

Figure 1. High zero current test. Upper panel: Zero current is in the range of ±0.00099 V. Lower panel: Zero current is higher than 0.00099 V when the OroboPOS-Connector is connected to the O2k-Main unit and when the OroboPOS is connected to the OroboPOS-Connector, indicating a potential electrical problem of both, the OroboPOS-Connector, and the OroboPOS.