ISO 22241-1:2019 is the first part of the ISO 22241 series, which specifies the quality requirements for the NOx reduction agent AUS 32 (commonly known by the trade name AdBlue® in Europe or DEF – Diesel Exhaust Fluid in North America). AUS 32 is an aqueous solution of 32.5% high-purity urea and 67.5% deionized water, used in Selective Catalytic Reduction (SCR) systems to reduce nitrogen oxide (NOx) emissions from diesel engines.

ISO 22241-1 is essential for ensuring that AUS 32 maintains chemical purity and compatibility with vehicle exhaust after-treatment systems. It forms the foundation for regulatory compliance, particularly with Euro VI, US EPA, and other global emission standards.
Need to ensure your AUS 32 production or use complies with ISO 22241? Contact support@demo.pacificcert.com!
ISO 22241-1:2019 applies to:
The standard covers chemical and physical quality characteristics of AUS 32 and is relevant throughout the supply chain to protect SCR systems from contamination and ensure emissions compliance.
The primary goal of the ISO 22241 series is to ensure the safe, effective, and durable use of AUS 32 in reducing NOx emissions from diesel engines. It also ensures compatibility with SCR systems, preventing failures due to impurities or degradation.
The ISO 22241 series includes the following parts:
Part | Title |
Part 1 | Quality requirements for AUS 32 |
Part 2 | Test methods for verifying AUS 32 composition |
Part 3 | Handling, transportation, and storage guidelines |
Part 4 | Refilling interface (filling system) for light vehicles |
Part 5 | Refilling interface for heavy-duty vehicles |
Part 6 | Specifications for quality assurance in production and supply |
Chemical Composition (as per ISO 22241)
Component | Requirement |
Urea content | 31.8–33.2% by mass |
Biuret | ≤ 0.3% by mass |
Aldehydes | ≤ 5 mg/kg |
Insolubles | ≤ 20 mg/kg |
Phosphate | ≤ 0.5 mg/kg |
Calcium, Iron, Copper, Zinc | Each ≤ 0.5 mg/kg |
Sodium, Potassium, Magnesium | Each ≤ 0.5 mg/kg |
Property | Specification |
Appearance | Colorless, clear liquid |
Density at 20°C | 1.087 – 1.093 g/cm³ |
Refractive index @ 20°C | 1.3814 – 1.3843 |
Alkalinity as NH₃ | ≤ 0.2% by mass |
Freezing point | Approx. -11°C |
All parameters must be measured using methods specified in ISO 22241-2, ensuring consistency and reproducibility.
Ensuring your DEF or AdBlue® meets these specifications? Contact support@demo.pacificcert.com!
Specifies standardized laboratory test methods to verify compliance with Part 1. Methods include:
Highlights critical precautions such as:
Use of stainless steel or specific plastics (HDPE) for tanks and pipes
Avoiding contact with non-compatible materials (e.g., copper, brass)
Storing between -11°C and 30°C to prevent freezing and decomposition
Protecting from direct sunlight and contamination
Specifies standardized nozzle and tank interface dimensions to prevent misfilling and ensure ease of use for:
Light-duty vehicles (passenger cars)
Heavy-duty commercial vehicles (trucks and buses)
Covers quality management in AUS 32 production and supply chain, including:
Batch control
Lab testing protocols
Tank cleaning procedures
Packaging integrity
Want to align with all ISO 22241 parts? Reach out to support@demo.pacificcert.com.

Need support? Contact us at support@demo.pacificcert.com!
To demonstrate compliance, maintain:

The global push for decarbonization and air quality improvement is accelerating adoption of clean diesel technologies. ISO 22241-compliant AUS 32 is central to these efforts:
Maintaining ISO 22241-1 compliance is now a regulatory necessity. Need help preparing for new regulations or market expansion? Contact support@demo.pacificcert.com!
We provide full support for ISO 22241 series compliance, including:
From urea manufacturers to truck fleet suppliers, we ensure ISO 22241 compliance from production to pump. Get certified and protect your product integrity—email support@demo.pacificcert.com!
Not legally mandatory, but often required by OEMs and regulators for SCR compatibility and market acceptance.
Aqueous Urea Solution 32.5%, commonly branded as AdBlue or Diesel Exhaust Fluid (DEF), used in SCR systems.
Through laboratory testing as per ISO 22241-2 using titration, spectroscopy, and ICP methods.
ISO 22241 covers quality and usage; ISO 22240 is withdrawn and replaced by ISO 22241 series parts.
No. Only automotive-grade urea that meets strict purity standards is permitted under ISO 22241.
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