Organization of the Qualitycheck Proficiency Testing


The purpose of the interlaboratory proficiency testing is an independent external evaluation control of the analytical competence of testing laboratories for determining the various measurement classes in different environmental matrices.

Coordination and Responsibilities

The management of each interlaboratory test evaluation is under the responsibility of Qualitycheck. Each evaluation test is run by a coordinator, who deals with the design (choice of matrix, measurands, concentration, time scheduling, statistical analysis, reporting, etc.) and its execution. A technical team supports the Coordinator in customer service and management of proficiency testing. The design and planning of the Proficiency Testing Qualitycheck is managed entirely, and it is the responsibility of Qualitycheck.


Each proficiency testing scheme organized by Qualitycheck is held every year at a rate that is two to three cycles a year. Visit the Registration page to view the time schedule of the proficiency testing schemes available.

Reference Materials

The proficiency test items distributed in our proficiency testing, are designed by Qualitycheck in terms of matrix, measurands, and concentration levels, based on the needs of laboratories and requirements set by law in the environmental field (Direttives 2000/60/CE - 2008/105/CE - 2013/39/UE, etc.).
Such materials correspond, as far as possible, in terms of matrix, measurands and concentration, the type of samples tested in routine tests of laboratories. Where it is not possible to provide real matrices, for stability issues and/or homogeneity, Qualitycheck provides, as test samples, simulated or concentrated solutions (spike) to be added during the test to a real matrix.
All test samples are prepared and characterized in terms of homogeneity and stability in accordance with international guidelines (ISO 17034, ISO GUIDE 35, ISO 17025, ISO 13528 and ISO/TS 22117) from qualified reference material producers selected by Qualitycheck.

Choice of method or procedure

Unless otherwise specified, participants can choose to use the test methods they consider most appropriate (methods used in their laboratory or methods to be validated).
The proficiency test items distributed in the Proficiency Testing Qualitycheck must be treated in the same way they have handled the samples routinely analysed.
In the case where the evaluation test involves the use of a specific test method, this method is clearly specified to the participants (ex. Proficiency testing (PT): Leaching test according to standard EN 12457-2).


Data analysis and evaluation of the proficiency testing schemes results

The statistical treatment of results is based on robust statistical methods that minimize the influence of outliers, as required by the technical standards: ISO 13528:2015 and ISO/TS 22117:2010 .
The evaluation of the results of participating laboratories is based on performance statistics (es. z-score).
The standard deviation for proficiency assessment is defined as Fit for Purpose and takes into account the state of the art performance of analytical techniques and testing standard methods, concentration levels, the type of matrix, and the requirements of laws and regulations governing reference. Furthermore, the evaluation of the performance takes into account the uncertainty of the value assigned, the degree of homogeneity, and stability of the test samples.


Assessment of the performance: Final Report

The results of the evaluation of the performance of the participating laboratories are made available to the laboratories within 10 working days before the useful deadline for sending results.
These results are published in a Final Report in accordance with the requirements of the standard CEI EN ISO/IEC 17043:2010.
The Final Report is published in English and is customized to each participating laboratory, as it includes a summary of its results and the valuation obtained.
In addition, the Final Report also includes the results of all the participants, information on the statistical treatment, the results of the performance evaluation of all participants (z -scores), and information on the preparation of test material.

The management of the Final Report, approval, and authorization for publication is done and is entirely the responsibility of Qualitycheck.



Qualitycheck uses procedures that guarantee confidentiality on the participation of the testing laboratories on the Qualitycheck Proficiency Testing. Each participant is assigned an alphanumeric identification code. This code is strictly restricted, confidential, and is communicated only to the contacts indicated by the laboratory in the registration form. All information provided by participants in the Qualitycheck is treated as confidential. In the Final Report, the results of any laboratory test are associated with the alphanumeric identifier in order to preserve its identity.