Beverage-Grade CO₂ Analysis & ISBT Compliance

Beverage-grade CO₂ is carbon dioxide pure enough to carbonate food and drink. The standard is set by the ISBT (International Society of Beverage Technologists) CO₂ Quality Guidelines, which require a minimum CO₂ purity of 99.9% v/v and cap more than a dozen trace impurities, benzene chief among them. ASTG builds the analytical systems that verify that specification continuously, on the live stream, with an audit trail. Our AirBreather platform measures benzene to 1 ppb, 20× below the ISBT limit, and is designed to meet the instrument-measurable requirements of the ISBT guideline and the CGA and EIGA specifications. It carries Coca-Cola approval NA-KO-102.

AirBreather CO₂ Analytical Systems

AirBreather Systems™ was developed by ASTG at the request of one of the world's largest beverage manufacturers, who wanted to modernize gas purity verification. It took five years to build, including two years of field trials and one year of in-service validation. The result is a robust, maintenance-friendly system that gives fast, reliable purity verification.

AirBreather uses new technologies for quality control, quality assurance and safety. Complete systems lower cost of ownership and increase throughput.

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Watch: AirBreather Systems overview

What the ISBT CO₂ guidelines require

The ISBT guidelines are the commercial baseline for beverage-grade CO₂. They list each controlled impurity, set a maximum limit for it, and name the method used to measure it. ISBT is not a regulator, but a producer who cannot demonstrate compliance will struggle to sell into the beverage market. The full list, with the limit of detection AirBreather achieves for each. All specifications are volume / volume (v/v) unless otherwise annotated:

ISBT limits reproduced from the 2021 edition, Revision 4.
‡ Original Source: ISBT Bulk Carbon Dioxide Quality Guidelines and Analytical Methods and Techniques Reference © 1999
Rationale, as ISBT defines it: Operational, a process control parameter. Food Safety, a parameter with the potential to be a food safety hazard. Sensory, a parameter with potential negative impacts on beverage taste, odor or appearance.
ISBT notes that beverage manufacturers should evaluate the sensitivity of their products to trace levels of these impurities, and that lower limits may be required for some products, to be agreed between supplier and customer.
AirBreather limits of detection as tested by ASTG. Carbon dioxide is the matrix gas, so its figure is an accuracy at the level measured rather than a limit of detection. The oxygen analyzer is an option.

Five lines carry a food safety rationale rather than a sensory or operational one: carbon monoxide, the oxides of nitrogen (total, NO and NO₂), and aromatic hydrocarbons, measured as benzene, at 20 ppb. Benzene is the limit that defines the rest. It is a known carcinogen, it is regulated rather than merely undesirable, and at 20 ppb its ceiling is among the tightest on the list. A system that resolves benzene with room to spare is usually one you can trust across the whole specification. For the full rationale, see What the ISBT CO₂ Quality Guidelines Actually Require.

How ASTG verifies beverage-grade CO₂

AirBreather measures the instrument-measurable ISBT parameters on one platform, continuously. Aromatics run on a dedicated GC-PID with an analyte-specific method for benzene, detected to 1 ppb. For ISBT reporting, aromatics are reported as benzene. Individual BTEX speciation (benzene, toluene, ethylbenzene and xylene) is available where an application requires it, which helps trace a contaminant back to its source. Sulfur and methanol are measured by FTIR (total sulfur to 0.010 ppm, methanol to 0.015 ppm), and oxygen, which infrared cannot see, is measured by an optional oxygen analyzer. The system analyzes multiple impurities simultaneously against the instrument-measurable requirements of the ISBT guideline and the CGA and EIGA specifications, and returns results in about four minutes. It runs on compressed air alone, with no carrier, span or calibration gases, and validates internally. It carries Coca-Cola approval NA-KO-102. See Beverage-Grade CO₂ Benzene Monitoring.

For CO₂ producers

AirBreather protects the certification your customers depend on. It runs continuous analysis at up to 12 sample points, uses Sample Safety Tech to prevent cross-contamination, and reads recycled and alternative CO₂ sources, which matters more as producers qualify new feedstocks against a tightening supply.

For bottlers

AirBreather protects quality at the point of use. Where CO₂ arrives by tanker, the optional DIP-1 driver interface panel lets the driver fill the storage tank through a secure sequence, and optional built-in alarms flag concentration, flow and diagnostic conditions. The Secure COA module issues certificates of analysis, an FDA 21 CFR Part 11 module is available for electronic records and signatures, the system is fully remote operable with full data support, and service intervals are one year.

Why detection margin matters

Meeting a limit on paper is not the same as proving it on a live stream, batch after batch. The value of a monitoring program is the margin between what the instrument can detect and the limit it is measured against. AirBreather's 1 ppb benzene detection limit sits 20× below the 20 ppb ISBT limit. That headroom is what turns a pass from an assertion into a defensible result when an auditor asks.

Beverage-grade CO₂ FAQ

What is beverage-grade CO₂?

Beverage-grade CO₂ is carbon dioxide purified to the standard required for food and drink, defined by the ISBT CO₂ Quality Guidelines: a minimum purity of 99.9% v/v with strict ceilings on trace impurities such as benzene, total sulfur, acetaldehyde and oxygen.

What are the ISBT CO₂ quality guidelines?

They are the beverage industry's reference specification for CO₂ quality, published by the International Society of Beverage Technologists. Each controlled impurity carries a maximum limit and a defined analytical method, grouped by operational, food safety and sensory rationale.

What is the ISBT limit for benzene in beverage-grade CO₂?

Aromatic hydrocarbons, expressed as benzene, are limited to 0.020 ppm v/v (20 ppb) on food safety grounds. ASTG's AirBreather detects benzene to 1 ppb, 20× below the limit. Individual BTEX speciation is available where an application requires it.

How is beverage-grade CO₂ tested?

Each impurity has a defined method. The most reliable programs measure continuously on the live stream (aromatics by GC-PID, sulfur and methanol by FTIR, oxygen by a dedicated sensor), corroborate the safety-critical results, and issue an auditable certificate of analysis.

Does ASTG's AirBreather meet ISBT, CGA and EIGA requirements?

For the requirements an instrument can measure, yes. AirBreather is designed to meet the instrument-measurable requirements of the ISBT guideline and the CGA and EIGA specifications, and carries Coca-Cola approval NA-KO-102. Non-volatile residues and the odor, taste and appearance tests are laboratory and sensory tests, which AirBreather does not perform.

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Related: Benzene monitoring · AirBreather · Model FT2-FTIR · Analysis by contaminant