The O2k-Manual provides the answers to many of these questions – and you find more information on our website …

Oxygraph-2k assembly (MiPNet12.06)

·       What is the most important consideration for positioning the glass chamber during assembly of the O2k?

·       How do I detect a leak in the chamber?

Polarographic oxygen sensor (POS) (MiPNet08.04)

·       Why is it important to check the non-calibrated raw signal (voltage, after current-to-voltage conversion) of the polarographic oxygen sensor?

·       Why is it important to maintain an extremely constant temperature in and around the O2k-chamber?

·       Does the POS respond to oxygen concentration, c_O2 [µmol∙dm^-3 = µM], or partial oxygen pressure p_O2 [kPa]?

POS calibration

·       How many calibration points are required for proper calibration of the polarographic oxygen sensor (POS)?

·       During POS calibration, should the chamber be open or closed?

·       What is an acceptable voltage (raw signal) of the POS at (a) air calibration, and (b) zero oxygen calibration, and how are these raw signals affected by the gain setting?

·       Why should you check the raw voltage during calibration?

·       The sensor voltage is above 9.9 V.  What should I do?

·       What does the stirrer test tell me?

·       How do I perform a zero oxygen calibration?

·       The oxygen solubility, S_O2 [µM∙kPa^-1], relates oxygen concentration to partial pressure. Which variables need to be considered for estimation of the oxygen solubility of an aqeous solution, for example of a respiration medium?

·       When is the oxygen calibration of a POS preferentially performed?

·       How long does it take approximately (5, 15, 30 or 45 min) to perform an oxygen calibration at air saturation, after the O2k is switched on (at experimental temperature in the range of 20 to 37 °C)?

·       Do you need to consider the instrumental background when performing an oxygen calibration of the POS at zero oxygen concentration?

·       Do you need to consider the instrumental background when performing an oxygen calibration of the POS at air saturation?

·       Does the oxygen signal have to be stable for an oxygen calibration of the POS?

·       How do you define POS signal stability?

·       Do you have to perform a zero oxygen calibration of the POS before air calibration?

·       Can you perform an oxygen calibration of the POS with biological sample and respiratory activity in the aqueous solution, when equilibration is performed with a gas phase in the chamber and stability of the signal is observed?

·       What is the difference between static calibration (MiPNet12.08) and dynamic sensor calibration (MiPNet02.04 – for advanced users)? How can I use a dynamic calibration (stirrer test) as a quick sensor test?

POS Service (MiPNet12.08)

·       Can I wash the sensor with 70 % or 99 % EtOH?

·       What should I do if the sensor connector threads appear dark and dirty?

·       The POS membrane box appears to have two types of membranes, which one should be applied to the sensor?

·       How can I avoid creating bubbles when  filling the electrolyte reservoir of the POS?

·       Can I repeat the ammonia treatment?

·       How can I check sensor performance?

·       What precautions should be taken when handling the sensor connector?

Cleaning of the Chamber

·       What solution should be placed in the chamber when the O2k is not in use (i.e. overnight, for a few days)?

·       Can detergents be used to clean the chamber and the PVDF stoppers?

·       What is the recommended cleaning procedure between experimental runs?

·       The glass chambers appear to have surface residue.  Can this be removed, what is the procedure?

·       The stirring bar gets stuck. What can I do?

Instrumental background calibration (MiPNet12.09)

·       Does the oxygen signal have to be stable for an instrumental background calibration?

·       Does the oxygen flux have to be stable for an instrumental background calibration?

·       How do we define flux stability? Is a flat red line always an indication of a stable flux?

·       Do I need to calibrate instrumental background flux at air saturation and zero oxygen concentration?

·       Do I need to calibrate the POS before performing an instrumental background calibration?

·       We use the symbol a° for the intercept at zero oxygen concentration, and the symbol b° for the slope of background oxygen flux as a function of oxygen concentration. In the analysis of instrumental background, we have obtained 0.022 and -1.7. Which value is a° and b°?

·       Does the background-corrected flux have to be zero when the oxygen signal is stable?

·       How often do I have to check the instrumental background?