Determination of cholecalciferol (vitamin D3) in selected foods by liquid chromatography: NMKL collaborative study.
Results are presented from an NMKL (Nordic Committee on Food Analysis) collaborative study of a method for the determination of cholecalciferol (vitamin D3) in foods. The method is based on the addition of an internal standard (vitamin D2), followed by saponification and extraction with n-heptane. The fraction that contains vitamin D2/D3 is separated by preparative normal-phase liquid chromatography (LC), and the analytes are determined by reversed-phase LC with UV detection at 265 nm. The method was tested by 8 participating laboratories. In this study 6 different matrixes were analyzed for cholecalciferol content: milk, liquid infant formula (gruel), cooking oil, margarine, infant formula, and fish oil. The contents varied from 0.4 to 12 microg/100 g. Three matrixes (milk, gruel, and margarine) were fortified with vitamin D3. In the other matrixes, vitamin D3 was added at 3 different levels at the Swedish National Food Administration. The milk was analyzed as a blind duplicate, whereas the other matrixes were analyzed as split-level pairs. The recoveries from the samples with vitamin D3 added varied from 93 to 102%. The repeatability relative standard deviation (RSDr) values for accepted results varied between 2.2% (fish oil) and 7.4% (cooking oil), whereas the reproducibility relative standard deviation (RSD(R)) values varied between 6.8% (margarine) and 24% (cooking oil).
Swedish National Food Administration, Box 622, SE-751 26 Uppsala, Sweden. anst@slv.se
Anders
A
Staffas
Arne
A
Nyman
D000465:Algorithms; D002762:Cholecalciferol / Q000032:analysis*; D002853:Chromatography, Liquid; D005504:Food Analysis; D006801:Humans; D007202:Indicators and Reagents; D007225:Infant Food / Q000032:analysis; D007231:Infant, Newborn; D008383:Margarine / Q000032:analysis; D009821:Oils / Q000032:analysis; D012015:Reference Standards; D012997:Solvents; D013056:Spectrophotometry, Ultraviolet
D007202:Indicators and Reagents; D009821:Oils; D012997:Solvents; D002762:Cholecalciferol; D008383:Margarine