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Attend our webinar "Continuous Gas Analysis for High-Quality Industrial and Medical Gases" on May 20, 2026 and learn how gas purity and overall gas quality can be measured using different analytical technologies.
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Medical gases such as oxygen, nitrogen, and medical air must meet stringent purity requirements to ensure patient safety and regulatory compliance. Even trace levels of contaminants can compromise therapeutic effectiveness or pose health risks, making continuous and reliable gas analysis essential throughout production, storage, and distribution.
Accurate purity measurement involves both the quantification of the primary gas (assay) and the detection of critical impurities at ppm to ppb levels. Advanced analytical technologies enable real-time monitoring and verification against standards such as pharmacopeia requirements, supporting consistent quality control and safe delivery of medical gases.
HORIBA's Trace Gas Monitor GA-370 or Carbon Monoxide Monitor APMA-380 use non-dispersive infrared (NDIR) photometry to measure trace levels of carbon monoxide (CO) with measurement ranges of 0–5 ppm in oxygen (O2), nitrogen (N2) or air backgrounds.
| O2 | O2 (93%) | N2 | Medical Air | |
|---|---|---|---|---|
| Assay | > 99.5% PMD | 90% < O2 < 96% PMD | > 99.5% GC | 20.4% < O2 < 21.4% PMD |
| CO impurity | < 5 ppm IR | < 5 ppm IR | < 5 ppm IR | < 5 ppm IR |
GA-370 Trace Gas Monitor
APMA-380 Carbon Monoxide Monitor
HORIBA's Multi-Component Gas Analyzer VA-5000 and Ambient Carbon Dioxide Monitor APCA-370 use non-dispersive infrared (NDIR) photometry to measure trace levels of carbon dioxide (CO2) and methane (CH4).
For measuring CO2 impurities in oxygen (O2), nitrogen (N2) or air backgrounds, VA-5000 offers measurement ranges starting at 0–300 ppm, while APCA-370 offers measurement ranges starting at 0–500 ppm.
For measuring CH4 impurities in helium (He), VA-5000 offers measurement ranges starting at 0–100 ppm, while APCA-370 offers measurement ranges starting at 0–50 ppm.
| O2 | O2 (93%) | N2 | Medical Air | He | |
|---|---|---|---|---|---|
| Assay | > 99.5% PMD | > 90% < 96% PMD | > 99.5% GC | O2 > 20.4% O2 < 21.4% PMD | > 99.5% GC |
| CO2 impurity | < 300 ppm IR | < 300 ppm IR | < 300 ppm IR | < 500 ppm IR | |
| CH4 impurity | < 50 ppm IR |
VA-5000 Multi-Component Gas Analyzer
APCA-370 Ambient Carbon Dioxide Monitor
HORIBA's Nitrogen Oxides Monitor APNA-380 uses cross-flow modulated chemiluminescence (CLD) to measure trace levels of nitrogen oxides (NOx). With a dilution system, measurement ranges down to 0–2 ppm can be achieved in oxygen (O2), nitrous oxide (N2O), carbon dioxide (CO2) or air backgrounds.
| O2 (93%) | N2O | CO2 | Medical Air | |
|---|---|---|---|---|
| Assay | 90% < O2 < 96% PMD | > 98% IR | > 99.5% IR | 20.4% < O2 < 21.4% PMD |
| NOx impurity | < 2 ppm CLD | < 2 ppm CLD | < 2 ppm CLD | < 2 ppm CLD |
APNA-380 Nitrogen Oxides Monitor
HORIBA's Sulfur Dioxide Monitor APSA-380 uses ultraviolet fluorescence (UVF) to measure trace levels of sulfur dioxide (SO2) and total sulfur. With a dilution system, measurement ranges down to 0–1 ppm can be achieved in oxygen (O2), carbon dioxide (CO2) or air backgrounds.
| O2 (93%) | CO2 | Medical Air | |
|---|---|---|---|
| Assay | 90% < O2 < 96% PMD | > 99.5% IR | 20.4% < O2 < 21.4% PMD |
| SO2 impurity | < 1 ppm UVF | < 1 ppm UVF | |
| Total sulfur impurity | < 1 ppm UVF |
APSA-380 Sulfur Dioxide Monitor
HORIBA’s Online Gas Analyzer EXM500-L uses UV spectroscopy to measure trace levels of nitrogen dioxide (NO2) with measurement ranges of 0–400 ppm in nitric oxide (NO) backgrounds.
| NO | |
|---|---|
| NO2 impurity | < 400 ppm UV |
EXM500-L Online Gas Analyzer
HORIBA's Multi-Component Gas Analyzer VA-5000 and the Trace Gas Monitor GA-370 can be used to measure various assays like suppressed oxygen (O2), suppressed nitrous oxide (N2O), suppressed carbon dioxide (CO2) or carbon monoxide (CO) in nitrogen (N2).
| O2 | O2 (93%) | N2O | CO2 | Med. Air | Syn. Med. Air | 5% CO in N2 | |
|---|---|---|---|---|---|---|---|
| Assay | > 99.5% PMD | > 90% < 96% PMD | > 98% IR | > 99.5% IR | O2 > 20.4% O2 < 21.4% PMD | O2 > 21.0% O2 < 22.5% PMD | CO > 4.75% CO < 5.25% IR |
VA-5000 Multi-Component Gas Analyzer
GA-370 Trace Gas Monitor
The GA-370 Trace Gas Monitor enables continuous, high-sensitivity monitoring of CO, CO2, CH4, and N2O in high-purity gases, supporting reliable quality control in air separation and semiconductor plants.
Download the brochure for detailed specifications and application insights.
The AP-380 Series consists of the APNA-380 for measuring nitrogen oxides, the APSA-380 for measuring sulfur dioxide, the APOA-380 for measuring ozone, and the APMA-380 for measuring carbon monoxide.
Download the brochures for detailed specifications and application information.
The VA-5000 Series is a configurable multi-component gas analyzer for environmental monitoring, energy applications, quality control, and CEMS, supporting up to four detector modules in a single enclosure.
Download the brochure for detailed specifications and configuration options.
The following application notes are available for download:
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N2, O2, Ar: Air separator
CO2: Industrial sources or combustion
CO: Methane reformer (HyCO)
H2: H2O electrolysis and methane reformer
NH3: Haber-Bosch process
N2O: Heating of NH4NO3
NO: Oxidation of NH3
He: Natural gas sources
C2H4: Steam cracker
Non-dispersive infrared photometry (NDIR)
Used to measure impurities and purity levels in CO, CO2, N2O, CH4, etc.
UV fluorescence (after oxidation)
Used to measure impurities in SO2, H2S and other sulfur-containing compounds (TRS, TS).
Paramagnetic detector (PMD)
Used to measure impurities & purity in O2.
Chemiluminescence detector (CLD)
Used to measure impurities in NO, NO2, NOx.
Flame ionization detector (FID)
Used to measure impurities in CH4, C2H6, etc.






