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Posted on 17 Jan,2026

Types of Reference Materials: CRMs vs RMs Explained

Reference materials play a vital role in ensuring accuracy, reliability, and traceability of laboratory measurements. They are widely used for instrument calibration, method validation, quality control, and performance verification. Broadly, reference materials are classified into Reference Materials (RMs) and Certified Reference Materials (CRMs). Although the terms are sometimes used interchangeably, they have distinct meanings, levels of characterization, and applications.

Reference Materials (RMs)

Reference Materials (RMs) are materials that are sufficiently homogeneous and stable with respect to one or more specified properties. They are commonly used as benchmarks in routine laboratory activities such as internal quality control, method development, and system suitability checks.

RMs may have indicative or assigned values, but these values may not always be accompanied by a full uncertainty statement or complete metrological traceability. Because of this, RMs are generally suitable for routine and comparative purposes rather than high-accuracy calibration.

Typical uses of RMs include:

• Day-to-day quality control checks
• Monitoring instrument performance
• Method comparison and development
• Training and proficiency improvement

RMs are valuable tools for laboratories, especially where certified materials are not available or where the level of accuracy required is moderate. However, their limitations must be understood to avoid misuse in critical applications.

Certified Reference Materials (CRMs)

Certified Reference Materials (CRMs) represent the highest level of reference material quality. A CRM is a reference material characterized by a technically valid procedure, accompanied by a certificate that provides:

• Assigned property values
• Associated measurement uncertainty
• Statement of metrological traceability
• Instructions for use and storage

CRMs are produced under stringent quality systems, typically in accordance with ISO 17034, and often involve inter-laboratory studies, multiple measurement methods, and rigorous statistical evaluation.

CRMs are essential for:

• Instrument calibration
• Method validation and verification
• Accuracy and trueness assessment
• Compliance with accreditation and regulatory requirements

Because CRMs provide traceable and uncertainty-defined values, they are widely accepted by accreditation bodies, regulators, and auditors.

Key Differences Between CRMs and RMs

Choosing Between RMs and CRMs

The choice between RMs and CRMs depends on the intended use and required level of confidence. For routine internal checks, RMs may be sufficient and cost-effective. However, for calibration, accreditation compliance, and high-stakes measurements, CRMs are indispensable.

Laboratories must ensure that the selected material is appropriate for the purpose, as required by standards such as ISO/IEC 17025 and ISO 15189. Misuse of RMs in place of CRMs can lead to inaccurate results, audit non-conformities, and loss of confidence.

Conclusion

Both RMs and CRMs play important roles in laboratory quality assurance. While RMs support routine activities, CRMs provide the highest level of confidence through certified values, uncertainty, and traceability. Understanding the difference enables laboratories to make informed decisions, ensure compliance, and maintain measurement accuracy and credibility.