Application of radiometric and isotope dilution-mass spectrometric techniques to the certification of edible oil and fat reference materials

Summary A method for the isotope dilution-mass spectrometric (ID-MS) determination of butyric acid C₄ in butter fat (RM164) was developed in order to support the data gathered from nine experienced European laboratories within the final certification exercise. The ID-MS results (3,46±0,06 g C₄/100 g fat) were in very good agreement with those obtained by classical GLC and HPLC techniques. (RM164 was finally certified at 3,49±0,06 g C₄/100 g fat). This paper reports briefly on a previous preliminary study undertaken to validate a procedure (agreed by the BCR-sterol group) for the isolation of the sterol from fats and oils. By use of labelled sterols and radiometric measurements it was shown that sterol recoveries were superior to 96%.The procedure was applied during the 3rd Intercomparison exercise for sterol determination in RM162 (Blend of Soya-Maize oil), for the GLC measurements of cholesterol in RM380 (Whole milk powder) and RM384 (Lyophilized pork muscle) and to the ID-MS determination of cholesterol in RM163 (blend of animal fats) and RM164 (anhydrous milk fat).