Talk:O2k-NO Amp-Module

Previous Product ID 30222-24

Discussion O2k-NO Amp-Module

See also: NO and oxygen @OROBOROS.

NO and H2O2 sensors use an amperometric measurement principle (Amp-Module), comparable to the polarographic oxygen sensor (POS), which yields an amperometric signal at a given polarization voltage. We supply custom-made stoppers that can accommodate such sensors. With all generations of O2k's it is possible to simultaneously measure NO and O2 concentrations. However, the details (required accessories, possibility to use both chambers) depend of the Series of the O2k. Please consult MiPNet15.05 NO-Manual for all details.

All amperometric sensors, like (H2S, H2O2) that have the same connection, can be used with the O2k. However, we have to mention that, while NO is measured by quite a few of our customers, the usability of any H2O2 electrode currently on the market is sometimes questioned. However, this depends on your sensitivity needs.

For prices of NO electrodes (shaft with 2 mm diameter) please consult the manufacturer, e.g. WPI. We offer the O2k-MultiSensor Stoppers and (if required for previous O2k-Series) the MultiSensor-Preamplifier 1/100.

NO-sensor calibration

I have a question regarding NO-sensor calibration. What method would you recommend?I just tried with a solution (outside of the Oroborous) recommended from the factory (0.05M H2SO4, 0.02M KI with addition of nitrite in different concentrations) This method worked fine, however, is this possible to do in the oroborous? Is that extremely acidic solution harmful to the POS membranes?Best regards Tomas Shiffer

Answer: Thats the method I always used. Its fine for the oxygraph (and of course very fine for the PTFE O2 membrane) but I have to admit the table I used got some "scars" :-) (from the KI).Fasching Mario 11:45, 10 March 2011 (CET)

Determining pre-polarisation times

Please not that for some sensors WPI states the suggested pre-polarisation time not in the manual of the sensor but only in the manual of the WPI electronics,e.g. in the manual for the [0=TBR4100&back=products| TBR4100] (Appendix A)

From user feedback for the WPI HPO-2 sensor: (The suggested polarization voltage for the the WPI H2O2 electrodes is 400 mV, thats means -400 mV have to be set in the O2k, see I 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 0.1M PBS solution." But I find 2 hours is not enough. I send it to you ,maybe it is helpful for your other customer.

Comment by Oroboros Instruments: With our experiences from the WPI NO electrode and the users experience with the WPI HPO electrode, it seems advisable to assume that required prepolarisation times will be 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 prepolarisation 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 improve (that is get closer to zero). This may easily be missed by not observing the slope for long enough. Fasching Mario 09:23, 23 January 2014 (CET)