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The Tandem is now the affordable industry standard for dedicated exhaust (CO2 and O2) gas analysis, for all laboratory, scale-up and commercial production applications.


The Tandem gas analyser is used by scientists and engineers to understand the cells in their fermenters and bioreactors in more detail.  Formerly the reserve of expensive equipment, you can now afford dedicated, individual, on-line monitoring and control of your processes. You gain the reliability and the flexibility required in your facility.


Other gas analysis equipment, such as a mass spectrometer, will help you get the oxygen (O2) and carbon dioxide (CO2) concentrations in your off-gas, but these analysers are high cost and often have problems due to the high water vapour content coming out of fermenters. Other CO2 and O2 gas analysers also suffer occasional difficulties to integrate their control software into the standard process controllers from Sartorius, Applikon, New Brunswick Scientific (Eppendorf) or others that are common in fermentation and cell culture.


The Tandem range however has been specifically designed for the fermentation and bioprocessing industry and for ease of integration.  We understand the equipment you already use, and how to benefit quickly from installing a new sensor.  We can provide application examples, practical help and simple step by step guides for you, whether you run one or two 50ml mini-fermenters or a facility with multiple 100m3 manufacturing bioreactors. The Tandem has already been installed on all these equipment ranges, and on almost all manufacturers' models, meaning you have the benefit of a flexible and portable analyser. The accuracy and precision of the sensors inside the analyser, plus the interface firmware, are designed for fermentation processes and their process control equipment.


Do I need a gas analysis?


How would I use the extra information?


How do you know whether you can gain from adding a Tandem to your process control equipment? If you are growing cells of any type in a bioreactor, you are likely to gain. To help you, the more of the statements below that apply to you, the more you can gain from gas analysis.




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No extra valves or switching equipment or software necessary - the Tandem plugs into your existing instrumentation extension.


  • I grow cells in a fermenter or bioreactor

  • I take samples to measure optical density, cell concentration or wet/dry weight

  • I plot graphs of cell density or biomass, or wish to calculate specific growth rate (µ)

  • I want to reduce the number of samples I take

  • I need to know glucose (or other substrate) uptake rates

  • I need to know oxygen uptake rates

  • I need to scale-up a bioprocess reliably to transfer to production

  • I run a fed-batch process

  • I run a continuous or steady-state process

  • I want to know when my cells change their metabolism

  • I wish to control carefully and accurately media and substrate additions

  • I want to reduce the amount of by-products produced by my cells

  • I make decisions based on an off-line sample, e.g. induction, start of media or substrate feed, change of substrate, harvest etc.

  • I need to characterise my process for validation work

If you are not sure of how to take advantage of CO2 and O2 gas analysis, please email us. We may have experience with your cell type and can help you. There is a surprising amount of knowledge you can get about your bioprocess from the Tandem, and most installations are relatively simple

Flexible installations

Avoids large capital outlays for multiple fermentation suites, unlike mass spectrometers. Can be used as a backup to existing mass spectrometer installations also.

Continuous Signal

Allows continuous feedback control (no gaps), greater analysis of process activity, faster process development and optimisation. It can be used as a dedicated measurement device for reliable control.

Metabolic Feeding

Allows real time calculation of variables such as carbond dioxide evolution rate (CER), oxygen uptake rate (OUR) & respiratory quotient (RQ). It is invaluable in a fed batch system where, for example, its output can be linked to control a feed pump.

Dedicated Measurement

Ensures reliable and reproducible results on every fermenter. Never lose information on your process. Slight changes in growth rate or small anomalies are often missed with a mass spectrometer or a DO probe.

Near Maintenance free

No on-site servicing required. Regular two-point re-calibrations recommended.


Download a pdf file:


Automated Calibration

Supports both manual and automated calibration options saving time and reducing risk, while ensuring a consistent and reliable measurement.



An article from Bioprocess International Magazine, with several case studies and background information about how gas analysis can improve the performance, automation and reliability of fermentation bioprocesses.

Download a pdf file:



SL-BW-3m: Bare wires, signal cable for Tandem and PRO. 10ft/3m


SL-BraunBC-3m: Sartorius signal cable, (Biostat B&C 15pin D) for TGA and PRO. 10ft/3m


SL-DCU-T-3m: Sartorius signal cable, (DCU Tower 5pin O) for TGA & PRO. 10ft/3m


SL-HEXA-10m: Signal cable, bare wires, 6 lines. 30ft/10m


SL-OCTO-10m: Two signal cables, bare wires, 4 lines each. 30ft/10m


SL-DODI-10m: Two signal cables, bare wires, 6 lines each. 30ft/10m


SL-RS232-3m: RS232 signal cable for PRO and Multiplexed Tandems. 10ft/3m




Standard Tandem service, including recalibration test, no parts included


Tandem PRO service, including recalibration test, no parts included


Multiplexed Tandem service, including recalibration test, no parts included





Tandem PRO Replacement Oxygen Sensor


Multiplexed Tandem Replacement Oxygen Sensor


Replacement Carbon Dioxide Sensor, all models (range CO2-X e.g. X=10%)


Service and repair of CO2 sensor, where possible


Replacement / Upgrade of electronics board in older style Tandems



cGMP Operation

Used in GMP operations around the world as well as being the gold standard for laboratory and scale.up processes.