Inadequate Control of Reference Standards

Inadequate control of reference standards and materials is one of the most critical failures within an analytical laboratory. Although it often goes unnoticed in routine operations, it directly impacts the accuracy of results and the reliability of measurements. After all, if the reference used to quantify or compare is not reliable, every result built on top of it becomes questionable. A common example: a reference standard used after its certification has expired, even if physically intact, technically invalidates any result calculated from it — without this being visible in the final report.

In technical terms, reference standards and materials are the foundation of metrological traceability. Therefore, any weakness in their control compromises the entire chain of analytical reliability.

What Does ISO/IEC 17025 Require About Metrological Traceability

The ISO/IEC 17025 standard requires that reference standards and materials be traceable to the International System of Units whenever technically possible, with valid certificates and documented control of use. In Brazil, this metrological traceability is overseen by INMETRO/Cgcre, the national metrology institute, in accredited laboratories — an example of how national accreditation bodies enforce this requirement in practice.

What Are Reference Standards and Materials in the Analytical Context?

Standards are substances or solutions with known concentration, used for calibration, construction of analytical curves, and verification of method performance. Reference materials, in turn, have assigned values for specific properties, accompanied by technical documentation proving their characterization.

These materials ensure that the result obtained in the laboratory is linked to a recognized value, reducing uncertainty and strengthening comparability across different analyses, instruments, and even different laboratories.

Without rigorous control of these inputs, the accuracy of the method is no longer supported by solid technical evidence.

Main Failures in the Control of Reference Standards and Materials

Among the most common failures is the use of expired standards or standards stored under inadequate conditions. Temperature, humidity, and light exposure can degrade sensitive substances, altering their actual concentration over time.

Another recurring failure is the absence of documentary traceability. When there is no clear record of lot number, manufacturer, certificate of analysis, and opening date, it becomes impossible to reconstruct the history of the standard used in a given analysis.

In addition, dilutions prepared without proper control of validity or without a record of the responsible technician significantly increase the risk of systematic error. Small inaccuracies accumulated over successive steps can generate significant deviations in the final quantification.

It is also common to find no structured program in place for periodic performance verification of working standards against primary reference materials.

Technical and Regulatory Consequences

The consequences of inadequate control are profound. First, analytical accuracy is compromised. Results may show systematic bias without the laboratory noticing immediately.

Next, inconsistencies arise in validation, verification, or quality control studies. When the standard is not properly characterized, it becomes impossible to distinguish whether the observed variation stems from the method or from the reference used.

From a regulatory standpoint, failures in standards control are frequently classified as critical nonconformities. Audits require evidence of metrological traceability, validity control, proper storage, and complete documentation.

In more serious situations, historical results may be called into question, requiring sample reanalysis or revision of issued reports.

How to Structure Effective Control of Reference Standards and Materials

Effective control begins with rigorous supplier qualification and documentary verification of certificates of analysis. Each standard must have unique identification, lot record, receipt date, opening date, and expiration date.

In addition, storage conditions must be monitored and recorded, ensuring material stability over time.

Working standards prepared in-house need a formal preparation procedure, documented calculations, a defined usage period, and a record of the responsible technician. The frequency of verification against certified reference material must also be defined based on risk analysis.

In parallel, internal audits help identify weaknesses in the system before they become critical problems.

LIMS as a Tool for Control and Traceability

In this context, a Laboratory Information Management System (LIMS) can significantly strengthen the control of reference standards and materials. The system allows each material to be registered with detailed information on lot, expiration date, supplier, and certificate of analysis.

In addition, the LIMS can issue automatic expiration alerts, block the use of expired standards, and link each analysis to the specific lot of the standard used. As a result, traceability becomes immediate and auditable.

Another significant advantage is inventory and consumption control, preventing unrecorded use or loss of critical material. The system also facilitates the association between the analytical curve and the standard employed, reinforcing data integrity.

However, as with other processes, the system does not replace technical discipline. If preparation is carried out incorrectly or if physical storage does not follow established conditions, electronic control will not correct the error. Technology structures the process, but technical responsibility remains with the team.

Conclusion

Inadequate control of reference standards and materials directly compromises the accuracy and reliability of analytical results. Without adequate metrological traceability, the laboratory loses the technical foundation that supports its measurements.

Implementing rigorous control means protecting data integrity, reducing the risk of systematic bias, and strengthening regulatory compliance. Moreover, it represents technical maturity and a commitment to scientific quality.

When well-structured procedures are paired with tools such as a LIMS system, the laboratory consolidates a more robust, transparent, and auditable management model.

In an environment where critical decisions depend on reliable quantitative data, reference standards and materials are not just operational inputs. They are the foundation of analytical credibility.