1. European Reference Laboratory for Food Contact Materials (EURL-FCM), EU
    website : http://ihcp.jrc.ec.europa.eu/our_labs/eurl_food_c_m/interlaboratory-comparisons
2. The Food and Environment Research Agency (FERA), United Kingdom
    website : http://www.fapas.com/proficiency-testing-schemes/fapas/
3. German Reference Office for Food  Proficiency testing and reference materials(DRRR GmbH)
    website : http://www.drrr.de/englisch/proficiency_testing.htm
4. Center for Laboratory Proficiency Testing (CLPT),  Department of Science Service, Thailand
    website : http://www.dss.go.th/dssweb/en/clpt/index.html