Specifications of the O2k

The OROBOROS Oxygraph-2k with DatLab software is world-wide the only instrument (sole source) which allows routine measurements to be made with specifications summarized under the term high-resolution respirometry (HRR).

HRR

The limit of detection of oxygen flux is as low as 1 pmol O2.s-1.ml-1. Oxygen backdiffusion at zero oxygen is <4 pmol.s-1.ml-1. Oxygen consumption by the polarographic oxygen sensor at air saturation and standard barometric pressure (100 kPa) is 2.7 ± 0.9 SD (114 test runs at 37 °C). These highly standardized instrumental background fluxes are a linear function of oxygen concentration, which is used for automatic background correction of oxygen flux (DatLab). Typical exponential time constants of the oxygen sensors are <4 s, used for dynamic corrections in kinetic studies. Signal noise at zero oxygen concentration is <0.05 µM O2.
Continuous control of the OROBOROS Oxygraph-2k specifications are a fundamental component of Quality Assurance and distinguish high-resolution respirometry from any conventional oxygraph system and from non-quantitative approaches.

Oxygraph-2k: technical specifications

General

• Dimensions - O2k-Main Unit: L 45 cm, W 31 cm, H 25 cm; 14 kg without packing box or Peli Case.

• Chambers: chemically inert and minimum oxygen diffusion:

- Two Duran glass chambers with 2 ml (1.5 to 3.5 ml) volume; 16 mm inner diameter.

- PVDF or PEEK stoppers with Viton O-rings.

- Electromagnetic stirrers with variable speed (100 to 900 rpm).

- PVDF- or PEEK-coated stirrer bars (6 mm diameter).

- Polarographic oxygen sensors (OroboPOS) sealed with butyl rubber seal tips.

• Built-in electronically regulated Peltier thermostat:

- Temperature range:

At room temperature	4 °C to 47 °C
At lower ambient temperature	2 °C

- Temperature stability:

Temperature stability

±0.002 °C over 90 min.

- Temperature range:

in 15 min	20 °C to 30 °C
in 20 min	30 °C to 20 °C

• Data output through USB:

- Two oxygen signals.

- Pressure transducer, for absolute barometric pressure signal, resolution 0.1 kPa.

- Thermostat temperature signal, resolution 0.001 °C.

- O2k-MultiSensor: two additional amperometric signals (O2k-fluorescence; NO sensors), and two additional potentiometric signals pX: for TPP or pH).

• DatLab software:

- Display: simultaneous display of oxygen concentration and oxygen flux (negative slope or time derivative), together with any selected O2k-MultiSensor channels (raw or calibrated signals and corresponding time derivatives). Barometric pressure for oxygen calibration; temperature stability control.

- Automatic calibrations: oxygen and O2k-MultiSensors.

Specifications for high-resolution respirometry

• Oxygen signal:

- Noise at zero oxygen: <0.005 kPa (SD, 100 data points recorded at 1 s intervals) without smoothing (±0.003 kPa typical)

- Noise at air saturation: <0.010 kPa (SD, 100 data points recorded at 1 s intervals) without smoothing, at partial oxygen pressure of 20 kPa (±0.005 kPa typical)

- Time constant: <7 s at 25 °C (<4 s typical)

- O2 range of linearity: Oxygen partial pressure of 0 to 100 kPa

• Oxygen flux:

- Limit of detection: 0.5 pmol.s-1.ml-1 at steady-state over 5 min.

- Sensitivity (normoxic): <1 pmol.s-1.ml-1 at steady-state over 5 min at 20 - 40 °C.

- Sensitivity (hyperoxic): <3 pmol.s-1.ml-1 at steady-state over 5 min at 20 - 40 °C.

- Noise: <0.2 pmol.s-1.ml-1 after standard smoothing (120 s).

- O2 range of measurement: Flux measured at oxygen partial pressure up to 100 kPa and to <0.01 kPa based on DatLab analysis of oxygen kinetics (mitochondria and cells)

• Instrumental background for linear correction over the entire oxygen range:

- O2 backdiffusion at 0 kPa:

<3 pmol.s-1.ml-1 at 20 to 40 °C (2.5 pmol.s-1.ml-1 typical)

- O2 consumption at 20 kPa:

<4 pmol.s-1.ml-1 at 37 °C (3 pmol.s-1.ml-1 typical)

<3 pmol.s-1.ml-1 at 25 °C (2 pmol.s-1.ml-1 typical).