Interlaboratory comparisons

Interlaboratory comparisons (ILCs) are organised either to check the ability of laboratories to deliver accurate testing results to their customers or to find out whether a certain analytical method performs well and is fit for its intended purposes. The former is usually termed 'proficiency testing' and the latter 'collaborative method validation study'. Only those methods passing the stringent requirements of such a study can be subject to standardisation by European or international standardisation bodies (European Committee for Standardization, CEN, and International Organization for Standardization, ISO).

Laboratories involved in official control activities are required to provide evidence for their competence in carrying out testing. This process is called accreditation. Accredited laboratories shall preferentially use standardised methods of analysis and are required to participate to proficiency tests for demonstrating their technical competence to their customers and to ensure comparability and acceptability of the testing results produced by them.

EU food and feed control legislation requires official control laboratories in the EU member states to use standardised methods, e.g. those issued by CEN, whenever available. The availability of standardised methods of analysis and sampling is therefore of great interest to all food chain stakeholders as it supports the uniform implementation of legislation in the EU Member States, in particular in cases where regulatory limits have been specified to ensure food safety.

In addition to protecting the well-being of consumers, standardised methods enable the free movement of goods within the EU and avoid duplication of analytical work commissioned by trading partners. When preparing documentary standards for food safety and quality, the JRC focuses on submitting collaboratively validated methods for the determination of regulated substances in food and feed.

Examples of standardised methods of analysis developed and validated by JRC are methods for the analysis of several mycotoxins in feed and food, food additives (sweeteners), heavy metals, coccidiostats, animal-by products, and foreign fats in chocolate. The validated methods submitted to the various standard developing organisations (ISO, CEN, AOAC International) are in part the result of pre-normative research activities linked to the operation of the EU reference laboratories (EURLs) hosted by JRC.

Next to collaborative method validation studies JRC organises proficiency tests through the operation of:

  • Regular European Interlaboratory Measurement Evaluation Programme (REIMEP) for nuclear measurements;
  • Interlaboratory Measurement Evaluation Programme for Nuclear Signatures in the environment (NUSIMEP);
  • International Measurement Evaluation Programme (IMEP).

The results of proficiency studies inform European Commission departments about the state-of-the-art in certain areas relevant for policy making, e.g. whether the currently available measurement techniques are suitable for enforcing an envisaged regulatory limit. The European co-operation for Accreditation (EA) profits as well as accreditors get an overview of the comparability of test results provided by accredited laboratories in the different countries; lastly, laboratories have a means to identify problem areas which allows them to take the necessary actions to remedy the shortcomings.

In the field of air quality monitoring, the European Reference Laboratory for Air Pollution (ERLAP) organises interlaboratory comparisons for air pollutants relevant to European Air Quality Directives. Regular tests take place for gaseous inorganic and organic air pollutants, and pollutants in the particulate phase are also considered upon request. The interlaboratory comparisons are organised for the National Air Quality Reference Laboratories of the AQUILA Network; if additional places are available other laboratories may be able to join upon request.


Various aspects of the interlaboratory comparison can from time to time be subcontracted.  When subcontracting occurs, it is placed with a competent subcontractor and the interlaboratory comparison provider is responsible for this work.

JRC Institutes