Differential Oxygen Analyzer
1 ppm O2 Resolution against Air
Qubit Systems’ S104 Differential O2 Analyzer (DOX) is the world’s only patented differential oxygen analyzer with a resolution of ± 1 ppm O2 against a background of air. Using the S104 DOX, researchers can measure real-time rates of respiratory oxygen consumption from tiny insects or photosynthetic oxygen production from a single intact leaf. The S104 Differential O2 Analyzer has the greatest dynamic range of any gas analyzer on the market and, at its lower resolution, can be used for respirometry measurements in large animals and humans. It has also been used extensively in environmental monitoring.

  • Single Leaf Photosynthetic O2 Exchange
  • Insect Respiratory O2 Consumption
  • Small and Large Animal Respirometry
  • Soil Respiration
  • Leaf Dark Respiration Rate
  • Human Metabolic Studies (Room Calorimetry)
  • Environmental Monitoring

Qubit's S104 DOX differential O2 analyzer was designed by researchers at Queen's University at Kingston in Canada to measure photosynthetic and respiratory O2 exchange rates to investigate the sources and sinks of electron flux in plant tissues. Numerous publications resulted, and the technique has been used by researchers worldwide to monitor O2 fluxes that were previously impossible to measure. When combined with Qubit's NDIR CO2 analyzers, the DOX opens new areas of investigation into respiratory exchange ratio and photosynthetic quotient. For a selection of publications citing use of the S104 click HERE and check the references.
A unique aspect of the DOX is that it requires no special calibration gas mixtures. To calibrate, a measured differential pressure is applied between the reference and analysis cells with dry ambient air flowing through both. A calculation in the Qubit software translates this into a perfectly accurate, and repeatable, differential O2 value, as shown in the calibration test data above. Calibration is linear over the entire range of the analyzer.
Multichannel Capability
(Mealworm Respirometry Data)
Qubit provides all the ancillary equipment (pumps, flow meters etc.) and software to integrate the DOX as part of a complete gas exchange system with, or without, our other gas analyzers for CO2, Methane, H2, Water Vapour etc. We also provide Gas Switching Systems for multichannel capability for the sequential measurement of several samples. Baseline measurements are made at user-defined intervals between sample measurements and any drift is corrected automatically. The DOX incorporates sensors for temperature and pressure within and external to the O2 sensor block to remove any effects of the environment on the O2 signals.
What are Clients Say...

When purchasing a new gas exchange system for research purposes, I took a chance with Qubit systems; they claimed to produce a competitive system at almost half the price of those of more established companies. I am happy to say that I am entirely happy with my decision. I now have a reliable and versatile system that is just as accurate as the more expensive competition and, because it is modular, can be expanded as my needs evolve. Most importantly, I received outstanding service during all phases of purchase: conception, ordering, installation and continuing help.
Dr. Bill Shipley, Département de Biologie, Université de Sherbrooke

Qubit Systems on the Road

Due to the COVID-19 crisis, we are unable to showcase our products at conferences and exhibitions. However, we hope to see you in the not-too-distant future. Until then, we wish you well. Stay safe and healthy.
Contact Us
Phone: 613-384-1977
Fax: 613- 384-9118

1573 John Counter Blvd. Kingston,
Ontario, Canada, K7M 3L5