OroboPOS
Description | The OroboPOS is a polarographic oxygen sensor (POS), with an amperometric mode of operation. The OroboPOS meets the highest quality criteria in terms of linearity, stability and sensitivity of the signal. The Clark type polarographic oxygen sensor (POS) remains the gold standard for measuring dissolved oxygen in biomedical, environmental and industrial applications over a wide dynamic oxygen range.
It consitsts of a gold cathode, a silver/silverchloride anode and a KCl electrolyte reservoir separated from the sample by a 25 Β΅m membrane (FEP). The main body of the OroboPOS is made of PEEK. With application of a polarization voltage (0.8 V), a current is obtained as an amperometric signal, which is converted to a voltage. |
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Product ID | 26000-01 |
Type | O2k, OroboPOS |
Link | MiPNet19.18B POS-Service, Gnaiger_1983_POS |
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Specifications
From nM to mM O2 - a million-fold dynamic range: The dynamic range of oxygen measurement spans from air saturation (about 200 Β΅M) to the normoxic intracellular range (10-30 Β΅M) and severe hypoxia (<1 Β΅M), but also to hyperoxia (oxygen saturation: c. 1 mM). In measurements of cell respiration in conjunction with the Titration-Injection microPump TIP2k, allow accurate steady-state measurement of oxgen levels and respiration with resolution of better than Β±1 nM.
Shipment
- O2k-Core: 2 OroboPOS are included and shipped in the O2k-Service Box. A spare (third) OroboPOS may be added to the items ordered with the O2k-System.
OroboPOS are protected in a transparent perspex vial screwed onto a blue POM base, with the OroboPOS-Membrane Ring arrested on the POS shaft between the POM base and the thicker part of the POS head which holds an O-ring\Viton\8x1 mm.
POS service and membrane mounting
>> O2k-Manual for OroboPOS Service
OroboPOS Technical Service Pages
The query description has an empty condition.
Trouble shooting
If a Stirrer test shows a slow response of the sensor some hints in Slow responding sensor.
As the heart of the OROBOROS Oxygraph-2k the OroboPOS is of course the prime suspect when any kind of troubles are encountered. However, frequently problems can be traced either to inadequate software settings or to other hardware components (like the POS connector). Therefore it is important to confirm the problem doing a Sensor test and to localize the problem.
Problems that require a full Sensor test and localization of the problem
- unstable O2 signal
- unstable O2 flux
- high O2 signal at air saturation
- high O2 signal at zero oxygen
Special cases: no further localization necessary
- Slow responding sensor, if this has been confirmed by a Stirrer test. Note: The stirrer test is part of the sensor test. It is therefore recommended to do a full Sensor test whenever problems are encountered.
General Trouble Shooting Procedure for the OroboPOS
Confirm the problem by doing a Sensor test in the absence of biological material
Option 1.A: No problem was visible in the Sensor test
check the following DatLab settings
- Gain (O2 channel)
- POS calibration
- Scaling
If the problem is not visible when observing the Raw signal but is visible when observing the calibrated oxygen signal, then there is probable a problem with the POS calibration.
Option 1.B: The problem was visible in the Sensor test
- proceed to Locate the Problem and the continue as stated below
Option 2.A: The problem could be localized on the POS
Solutions 2.A Follow the instructions for oxygen sensor service [MiPNet08.04]. Use this opportunity to apply contact oil to the gold pin and thread connecting POS and sensor connector. After a sensor service or after applying anew membrane allow the oxygraph to run over night to achieve a stable signal before repeating the sensor test. If all service precautions fail to solve the problem, the POS has to be sent to us for further service (a recovery can not be guaranteed), or a new sensor is to be applied.
Option 2.B: The problem was not localized on the POS
Solutions 2.B If the problem was localized on an other component follow the instructions for this component. If you could not locate the problem contact OROBOROS Instruments.
References
- Gnaiger E, Forstner H, eds (1983) Polarographic Oxygen Sensors. Aquatic and Physiological Applications. Springer, Berlin, Heidelberg, New York: 370 pp.
- Gnaiger E (2001) Bioenergetics at low oxygen: dependence of respiration and phosphorylation on oxygen and adenosine diphosphate supply. Respir Physiol 128: 277-297.
- Gnaiger E (2008) Polarographic oxygen sensors, the oxygraph and high-resolution respirometry to assess mitochondrial function. In: Mitochondrial Dysfunction in Drug-Induced Toxicity (Dykens JA, Will Y, eds) John Wiley: 327-352.