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Abstract: Fasching M, Gnaiger E (2014) O2k-MultiSensor system with amperometric sensors: NO, H2S, H2O2. Mitochondr Physiol Network 15.05(04):1-8. - Versions
O2k-Manual: NO, H2O2 and similar sensors are amperometric sensors, as is the OROBOROS polarographic oxygen sensor (OroboPOS). The measured current is converted to a voltage, amplified and recorded by DatLab.
• O2k-Network Lab: AT_Innsbruck_OROBOROS
Labels: MiParea: Instruments;methods HRR: Oxygraph-2k, NO, O2k-Manual Additional: O2k-MultiSensor, O2k-SOP
This information is part of O2k-technical support and open innovation.
O2k signal and output
Electrochemical NO and H2O2 sensors
- NO and H2O2 sensors use an amperometric measurement principle (Amp-Module), comparable to the polarographic oxygen sensor (OroboPOS), which yields an amperometric signal at a given polarization voltage. We supply custom-made stoppers that can accommodate such sensors. All amperometric sensors (NO, H2S, H2O2) that have the same connection can be used with the O2k.
- I have a question regarding NO-sensor calibration. What method would you recommend? I just tried with a solution (outside of the OROBOROS O2k) recommended from the factory (0.05 M H2SO4, 0.02 M KI with addition of nitrite in different concentrations). This method worked fine, however, is this possible to do in the O2k? Is that extremely acidic solution harmful to the POS membranes? Best regards ~ Schiffer TA
- Answer: That is the method we always used. It is fine for the O2k and no problem for the PTFE O2 membranes. But I have to admit that the laboratory table got some "scars" :-) from the KI, and the blue POM chamber holders may change colour. ~ firstname.lastname@example.org, 10 March 2011
- For some sensors WPI states the suggested pre-polarisation time not in the manual of their sensor but only in the manual of the WPI electronics.
- User feedback for the WPI HPO-2 sensor: The suggested polarization voltage for the WPI H2O2 electrodes is 400 mV, that means -400 mV have to be set in the O2k (see MiPNet15.05 NO-Manual). I have also contacted with WPI. They said that "The ISO-HPO-2 polarized at 450 mV for 2 hours in 0.1 M PBS solution." But I find 2 hours is not enough. I send this information to you, maybe it is helpful for other customers.
- Comment by OROBOROS: Based on our experience with the WPI NO electrode and our users experience with the WPI HPO electrode, the required prepolarisation time is longer than the (minimum) cited by WPI. Especially for the first run we suggest to allow for a very long pre-polarisation time (minimum over-night, days for NO) and to observe the slope of the signal. Only when the slope of the signal (not the signal itself !) is constant for a long time (hours), pre-polarisation is finished. This will give an indication for the proper pre-polarisation time in further experiments. It is important to continue the pre-polarisation for a few hours after the slope appears to be constant. In the later phase of pre-polarisation the slope may change very slowly but may still approach closer to zero. This can only be detected by recording the slope for a sufficiently long period of time. ~ email@example.com, 23 January 2014