Metrological traceability: what it is and why it matters

For laboratories using metrological gas mixtures in analytical processes, ensuring traceability safeguards the reliability of data. Every measured value must be traceable to a primary standard through an unbroken chain of certified references.  

Metrological traceability goes beyond regulatory compliance. It is a practical tool that directly affects measurement uncertainty, repeatability, and the comparability of results. 

Understanding how traceability works in gas mixtures, which requirements must be met, and how to read calibration certificates helps reduce errors and improve the efficiency of quality control.  

Metrological traceability: definition and practical application in gas mixtures 

Metrological traceability is the property of a measurement result that allows it to be related, with a stated uncertainty, to one or more internationally recognized references, generally provided by National Metrology Institutes (NMIs). 

For metrological gas mixtures, this means that each reported concentration must be traceable to a primary standard through a documented and uninterrupted series of calibrations. 

A metrological gas mixture can be considered truly traceable only if: 

• Its value has been determined using validated and recognized methods;
• The references employed are themselves traceable;
• The entire chain is fully and transparently documented.  

A certificate alone is not sufficient. It must clearly state the references used, environmental conditions, associated uncertainty, and the precise identification of the metrological standards applied. 

The impact of metrological traceability on data reliability 

Well-structured metrological traceability reduces measurement uncertainty, thereby increasing the technical and legal value of data. It has a direct impact on: 

• Calibration of instruments;
• Validation of analytical methods;
• Inter-laboratory comparisons;
• Responses to audits and inspections. 

When a gas mixture is not adequately traceable, the risks include results that are non-repeatable, difficult to compare, or unacceptable to accreditation bodies. 

In regulated contexts such as ISO/IEC 17025 or sectors like environmental, pharmaceutical, or food analysis, data integrity also depends on the metrological quality of the gases used. 

Traceability, therefore, is not a minor formal detail. It is a criterion to be assessed carefully, as it represents a cornerstone of scientific robustness. 

How to check the traceability of metrological gas mixtures 

Verifying the traceability of a gas mixture requires a critical review of the calibration certificate. Key elements to look for include: 

• References to primary or internationally recognized standards;
• Stated measurement uncertainty;
• References to applied ISO standards;
• Identification of the laboratory or institution responsible for the measurement. 

Compliance with ISO 17025 and ISO 17034 ensures that production, measurement, and certification processes follow internationally recognized procedures.  

Relying on suppliers who operate under these standards reduces the risk of non-conformities in internal processes and ensures continuity in metrological quality.  

For better laboratory management, it is also advisable to maintain internal traceability of gas batches, certificates, and expiration dates, integrating them into maintenance protocols and quality management systems.