Instrument

Medusa

The ultimate preconcentration system for cryogen-free, automated background monitoring of ODS & GHGs

The Medusa preconcentration system is well-established as a high-performing system for the precise background monitoring of ozone-depleting substances (ODS) and greenhouse gases (GHGs).

Medusa is the only instrument that has been demonstrated to measure NF₃ in ambient air samples at background levels (2–4 ppt), and is a trusted instrument used globally by the AGAGE network and by NOAA for over 45 years.

Designed by the AGAGE laboratory at the Scripps Institute of Oceanography, and built by Markes, Medusa traps up to 2 L of air, enabling confident measurement of sub-ppt compound concentrations. Its advanced management of interferents, including removal of water with Nafion membrane dryers, ensures reliable data collection. With a linear response over a wide range of sample concentrations and ‘sandwich calibration’ for ambient air samples, Medusa provides accurate, consistent measurements critical for atmospheric research.

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Market-leading advantages of Medusa

High-performance – Medusa is the only instrument demonstrated to measure NF₃ in ambient air samples at background levels (2–4 ppt).
Confident reporting – Management of interferents (H₂O and CO₂) is standard, allowing high sensitivity for all controlled ODS and GHGs.
Reliable – Water and CO₂ management help to enhance analytical repeatability, avoid analyte suppression, and increase instrument uptime.
Flexible – Medusa is suitable for laboratory or field measurements.
Convenient in the field – Cryogen-free cooling is economical, and makes Medusa suitable for field measurements, as well as allowing continuous running for laboratories and field measurement stations.
Cost-saving – Electrical cooling allows analysis of compounds as volatile as NF₃ without the inconvenience of cryogen, and the associated risk of flow-path ice blockages.
Easy to use remotely – Medusa uses the GCWerks software, streamlined for remote monitoring, enabling functional data review, and already used extensively for regional and global network control.
Adaptable – Options for loop or metered addition enable a wide range of samples or standards to be run, with pressures from sub-ambient pressure to 50 psig, and concentrations from ppt to ppm level.