Improvements in the determination of vitamins in foods: method intercomparison studies and preparation of certified reference materials (CRMs)

Accurate methods for the determination of vitamins in food are required for nutritional labelling, and for the production of food composition data for nutritional research on relationships between diet and health. The Standards, Measurement and Testing Programme of the European Commission is supporting a collaborative project involving 48 laboratories to improve their measurement in food. The research programme involves the use of method intercomparison studies to identify and control systematic errors, optimization of sample extraction and clean-up procedures, and the preparation of suitable food reference materials (RMs). Results are presented for the determination of vitamin D3 by HPLC and folates by microbiological assay in various foods demonstrating improved agreement between laboratories and possible reasons for improvements. In addition, examples of the food RMs produced and their potential use are described.