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Vitamin K external quality assurance scheme (KEQAS)


KEQAS is an international scheme that monitors and reports on the accuracy of vitamin K1 ( phylloquinone ) analysis.

KEQAS is overseen by a steering committee.

KEQAS steering committee members

Dr Dominic Harrington (scheme director)
Consultant clinical scientist, Human nutristasis unit, Centre for Haemostasis and Thrombosis

Dr Martin Shearer (chairman)
Consultant clinical scientist, Centre for Haemostasis and Thrombosis

Dr Leon Schurgers (scientific director)
Senior Scientist, Department of Biochemistry, University of Maastricht, The Netherlands 

Mr David Card MSc (scheme manager)
Centre for Haemostasis and Thrombosis


At the 10th meeting of the European Fat-soluble Vitamins Group in 1996, it was agreed that a quality assurance scheme for the determination of vitamin K1 should be initiated since self “in-house” assessment of laboratory performance makes it difficult to identify systematic errors. It was decided that participation in an external quality assurance scheme would greatly assist the development and harmonisation of methods for vitamin K analyses and their application to nutritional and clinical studies.

Participating laboratories receive four batches of three samples annually and are required to analyse them during specific periods over the course of the year. When results are returned they are subjected to statistical analysis including an outliers test and a Z scoring system. Members then receive comprehensive reports detailing their performance.

KEQAS is a UKNEQAS affiliated EQA scheme. Viapath Analytics LLP, operating KEQAS, is a UKAS accredited proficiency testing provider (No. 7586). A standard reference material is now available and pilot schemes for menaquinone -4, menaquinone -7 and vitamin K1 -2,3- epoxide are now in place.


Please email David Card and include your contact name and address to which samples should be sent.