Determination of vitamin D-3 metabolites: state-of-the-art and trends

The steps involved in the methods for the determination of vitamin D-3 meta bolites (namely, 25-hydroxyvitamin D-3, 1,25-dihydroxyvitamin D-3, 24,25-di hydroxyvitamin D-3) mainly in clinical samples are critically reviewed. Sam ple pretreatment (e.g. deproteinization, saponification, liquid-liquid and liquid-solid extraction, etc.) as a function of both type of sample and det ection system, quantitation based on protein saturation and liquid as well as gas chromatography are discussed. The chemical principles on which the m ethods are based and the derivatization procedures, which facilitate separa tion and/or detection, are also commented upon. Finally, the future prospec ts of the research on methods for the determination of these metabolites ar e outlined. (C) 1999 Elsevier Science B.V. All rights reserved.