Interlaboratory Comparison Tests as a Tool for Improving Measurement Quality in the Laboratory

Interlaboratory comparison tests, interlaboratory comparisons (ILC) in Russia are conducted in accordance with GOST ISO/IEC 170432013 “Interstate Standard. Conformity assessment General requirements for proficiency testing” (effective until April 10, 2026, after which it is superseded by GOST ISO/IEC 170432025 “Conformity assessment General requirements for the competence of proficiency testing providers”). Participation in ILC allows laboratories to monitor their performance, including comparing measurement results with those of other participants.

However, an analysis of ILC results obtained in 2021–2024 revealed hidden errors made by participants that led to unsatisfactory results. Thus, laboratories have not fully exploited the potential of ILC for monitoring their activities and identifying their own errors.

The objectives of the study presented in this article are to identify and analyse the main problems (errors) that can affect the reliability of measurement results and to draw laboratories’ attention to the possibilities offered by ILC for monitoring and improving their performance.

To this end, the results of ILC conducted by UNIIM – Affiliated Branch of the D. I. Mendeleyev Institute for Metrology were analysed. The study was based on ILC results for the objects “air environments”, “petroleum products”, and “food products”. During such ILC, participants obtained quantitative measurement results using equipment specified by the measurement procedure. The analysis described in this study did not cover qualitative and interpretative ILC programmes.

The analysis identified possible causes of unsatisfactory ILC results, provided examples and recommendations to help prevent unsatisfactory measurement results in the future.

The study established the main causes of errors: random errors, systematic errors, and errors related to incorrect descriptions of measurement procedures and/or calculation of measurement results in documents containing measurement procedures. The researchers concluded that with careful attention by laboratories to ILC results and regular participation in ILC, the proportion of unsatisfactory ILC results decreases significantly. Such attention leads to improved laboratory performance and, consequently, to increased reliability of measurement results.

The materials of the article are of an applied nature. The authors have demonstrated that analysis of each deviation in ILC results can improve the reliability of measurement results, as well as the effectiveness of this procedure in preparing laboratories for accreditation. The practical recommendations proposed for critical analysis of measurement results obtained during ILC are based on the extensive experience of the provider, whose staff are the authors of the article.

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