Indexed on: 01 Feb '93Published on: 01 Feb '93Published in: Fresenius' journal of analytical chemistry
In order to improve the methods for the determination of vitamins in food for nutritional purposes, the Commission's Community Bureau of Reference (BCR) has initiated a comprehensive research programme consisting of intercomparisons of methods to identify and eliminate sources of error and the preparation of reference materials (RMs). Six food RMs have been prepared to date including brussels sprouts, mixed vegetables and pigs' liver (all in the lyophilised form), vitamin enriched milk powder, wholemeal flour and margarine. The first five materials have been packaged into heat sealable, aluminium-laminate sachets under an inert atmosphere; margarine is a canned product. The initial homogeneity results have indicated no detectable signs of inhomogeneity for the vitamins/RMs investigated. Stability testing has monitored both short-term stability at elevated temperatures (+25 to 40°C, 8 weeks) and long-term stability −30 to +20°C, 36 months). The former was used to evaluate the effect of adverse shipment conditions on vitamin stability. Vitamins C and B1, two of the more labile vitamins, have been found to be stable for up to 4 weeks at +25°C and 8 weeks at +37°C in brussels sprouts (RM 431) and wholemeal flour (RM 122), respectively.The results of long-term stability testing of vitamins C and B1 in these RMs indicate there was no significant degradation of vitamin C in RM 431 for up to 24 months at −18 and +4°C when the data was expressed on the basis of the −30°C data (analytical control). Similarly, no significant degradation for vitamin B1 in RM 122 was found at +4 and +20°C for up to 12 months, again after expressing the data on the basis of the analytical control (−20°C). Once acceptable homogeneity and stability results have been found, certification studies for each vitamin/RM are planned.