vitamin-d-2 and isotachysterol

A new procedure for the isomerization of vitamin D and its metabolites is described. Vitamin D or its metabolites are dissolved in 100 microliters methanol and 10 M HC1 in 2-butanol is used as the reagent for isomerization. The isomerization reaction is carried out at 5 degrees C for 2-3 min which gives quantitative yields of isotachysterols down to 10 ng level without use of any carrier.

Topics: Calcifediol; Cholecalciferol; Chromatography, High Pressure Liquid; Ergocalciferols; Ergosterol; Isomerism; Methanol; Solvents; Temperature; Time Factors; Vitamin D

A high-performance liquid chromatographic (HPLC) method for estimating plasma 25-hydroxyvitamin D2 (25-OHD2) and 25-hydroxyvitamin D3 (25-OHD3) is described. The method involves plasma extraction, Lipidex 5000 chromatography and HPLC on straight-phase Zorbax-SIL, collecting the 25-OHD2 + 25-OHD3 fractions. These secosteroids are isomerised to their isotachysterol derivatives and re-run in the same HPLC system, monitoring at 290 nm. 3H-Labelled 25-OHD3 is used as an internal standard. The method was evaluated in terms of reproducibility, and recovery of added secosteroids was quantitative. Values obtained using this method were in close agreement with those values obtained on the same plasma sample using gas chromatography--mass spectrometry.

Topics: 25-Hydroxyvitamin D 2; Calcifediol; Chromatography, High Pressure Liquid; Ergocalciferols; Ergosterol; Gas Chromatography-Mass Spectrometry; Humans; Hydroxycholecalciferols; Secosteroids

Topics: Cholecalciferol; Chromatography, Gas; Ergocalciferols; Ergosterol; Methods; Secosteroids

Topics: Chemical Phenomena; Chemistry; Chromatography, Gas; Colorimetry; Ergocalciferols; Ergosterol; Fluoroacetates; Methods; Secosteroids; Spectrophotometry, Infrared; Spectrophotometry, Ultraviolet; Sterols; Time Factors

Topics: Acetates; Antimony; Benzoates; Chlorides; Colorimetry; Ergocalciferols; Ergosterol; Research; Spectrum Analysis; Ultraviolet Rays; Vitamin D; Vitamins