Statistical analysis of instrumental reproducibility as internal quality control in high-resolution respirometry

Abstract

Evaluation of instrumental reproducibility is a primary component of quality control to quantify the precision and limit of detection of analytical procedures. A pre-analytical instrumental standard operating procedure (SOP) is implemented in high-resolution respirometry consisting of: (1) a daily SOP-POS for air calibration of the polarographic oxygen sensor (POS) in terms of oxygen concentration c_O2 [µM]. This is part of the sensor test to evaluate POS performance; (2) a monthly SOP-BG (background) starting with the SOP-POS followed by the chamber test quantifying the instrumental O₂ background flux. The chamber test focuses on the slope dc_O2/dt [pmol∙s⁻¹∙mL⁻¹] to determine O₂ consumption by the POS and O₂ backdiffusion into the chamber as a function of c_O2 in the absence of sample. Finally, zero O₂ calibration completes the sensor test.

We applied this SOP in a 3-year study using 48 Oroboros O2k chambers. Stability of air and zero O₂ calibration signals was monitored throughout intervals of up to 8 months without sensor service. Maximum drift over 1 to 3 days was 0.06 pmol∙s⁻¹∙mL⁻¹, without persistence over time since drift was <0.004 pmol∙s⁻¹∙mL⁻¹ for time intervals of one month, corresponding to a drift per day of 0.2 % of the signal at air saturation. Instrumental O₂ background -dc_O2/dt was stable within ±1 pmol∙s⁻¹∙mL⁻¹ when measured at monthly intervals. These results confirm the instrumental limit of detection of volume-specific O₂ flux at ±1 pmol∙s⁻¹∙mL⁻¹. The instrumental SOP applied in the present study contributes to the generally applicable internal quality control management ensuring the unique reproducibility in high-resolution respirometry.

Cite:

Baglivo E, Cardoso LHD, Cecatto C, Gnaiger E (2022) Statistical analysis of instrumental reproducibility as internal quality control in high-resolution respirometry. Bioenerg Commun 2022.8. https://doi.org/10.26124/bec:2022-0008