EQA Program Organiser	Country	Survey name	Vitamins offered as part of the same program	Sample frequency	Website
RCPAQAP	Australia	Vitamin	A, E, B1, B2 B6 (whole blood and plasma), C, β-carotene and Total carotenoids	2 samples per survey; 12 surveys per year. Total of 24 samples per annum.	www.rcpaqap.com.au/chempath
CDC	United States of America	VITAL	A	9 samples to be run in duplicate over three days per survey, 2 surveys per year. Total 18 samples.	www.cdc.gov/labstandards/vitaleqa.html
DGKL	Germany	Vitamins and analgesics	A, B6, B12, D, E and folate	2 samples per survey, 2 surveys per year. Total 4 samples per annum.	www.dgkl-rfb.de
NEQAS	United Kingdom	Vitamin Assays (Carotene and Vitamins A & E)	A, E, β carotene, Total carotenoids, Carotenoid fractions (Vitamin K offered as a separate program)	5 samples per survey, 6 surveys per year. Total 30 samples per annum.	www.ukneqas.org.uk/
NIST	United States of America	Micronutrients Quality Assurance Program	Total retinol, trans retinol, Vitamin E fractions, β-carotene, Carotenoid fractions	5 samples per survey; 2 surveys per year. Total of 10 samples per annum.	www.nist.gov/mml/csd/organic/mmqap.cfm
SKML	The Netherlands	Vitamin A/E and β-carotene	A, E, β-carotene (Whole blood Vitamin B1 and B6 offered as a separate program)	6 samples per survey, 2 surveys per year. Total 12 samples per annum.	www.skml.nl/en/rondzendingen/overzicht/rondzending?id=58

CAP, College of American Pathologists; CDC, Center for Disease Control and Prevention; DGKL, Deutsche Vereinte Gesellschaft fur Klinische Chemie und Laboratoriumsmedizin; RCPAQAP, RCPA Quality Assurance Programs; NEQAS, National External Quality Assurance Program; NIST, National Institute of Standards and Technology; SKML, Stichting Kwaliteitsbewaking Medische Laboratoriumdiagnostiek.