MitoPedia O2k and high-resolution respirometry: O2k-Open Support
The O2k-sV-Module is the O2k small-volume module, comprised of two Duran® glass chambers of 12 mm inner diameter specifically developed to perform high-resolution respirometry with reduced amounts of biological sample, and all the components necessary for a smaller operation volume V of 0.5 mL. The current DatLab version is included in the delivery of this revolutionary module.
Reference: Product details and purchase information
Titration to the 0.5-mL O2k-chamber
In application of various SUIT protocols available in DatLab 7.4, the standard Hamilton syringes provided by Oroboros can be used for titration to the 0.5-mL O2k-chamber as there is no apparent retention of chemicals injected through the stopper of the O2k-sV-Module. Despite the slight recess of the needles depending on the particular Hamilton syringe type, the entire injected volume is mixed into the effective 0.5 mL experimental volume. In contrast to the stoppers of the 2-mL O2k-chamber, the needles fit the stopper capillary diameter of 1.00 mm rather tightly, such that upon removal of the syringe the residual dead volume is mixed into the experimental chamber volume, since the small space between needle and capillary ensures laminar downwards flow (in contrast to turbulent flow) with a jet effect directed into the mixed experimental compartment. Our experimental evidence does not show any delay of mixing after retrieval of the Hamilton syringe. Accurate kinetic titrations, however, require application of the TIP2k, with accurately placed needles extending slightly into the mixed volume without touching the stirrer.
Oxygen calibration in the 0.5-mL O2k-chamber
During Air calibration (O2k Quality control 1), in the open chamber, the raw oxygen signal is independent of the volume of the aqueous phase in the chamber and should be between 1 and 3 μA (V in DatLab 7.4 or older) from sea level up to 1000 m altitude (pb 90 - 101 kPa) and temperature between 25 - 37°C in both 0.5-mL and 2-mL O2k-chambers. However, the instrumental oxygen background flux (O2k Quality control 2) is volume-dependent in the closed O2k-chamber and higher values of J°1 are obtained in the 0.5-mL compared with the 2-mL O2k-chamber. The standard oxygen calibration procedure is described in detail here: MiPNet06.03 POS-calibration-SOP.