25-Hydroxyvitamin D isomerizes to pre-25-hydroxyvitamin D in solution: considerations for calibration in clinical measurements.
Anal Bioanal Chem
; 407(26): 8079-86, 2015 Oct.
Article
en En
| MEDLINE
| ID: mdl-26359234
ABSTRACT
Reference standards for the vitamin D metabolites 25-hydroxyvitamin D3, 25-hydroxyvitamin D2, and 3-epi-25-hydroxyvitamin D3 were evaluated using liquid chromatography (LC) with ultraviolet (UV) absorbance and mass spectrometric (MS) detection to assess purity. The chromatograms for solutions of all three 25(OH)D compounds, obtained using a pentafluorophenyl (PFP) stationary phase, revealed peaks that increased in area over time and had MS spectra that were nearly identical to the parent compound, indicating isomers had formed in solution that were unrelated to the reference standard purity. However, when the purity evaluations were completed with a cyanopropyl stationary phase, the isomeric products coeluted with the parent compounds and were not observable. The rates of formation of the isomeric products were found to increase when heated and were confirmed to be pre-25-hydroxyvitamin D compounds using spectral information from both MS detection and nuclear magnetic resonance (NMR) spectroscopy. The rates of conversion of 25(OH)D3 to pre-25(OH)D3 was studied in solutions of ethanol and bovine serum albumin (BSA) in phosphate-buffered saline (PBS). The solutions prepared with BSA/PBS were found to form twice as much pre-25(OH)D3 as the solutions in ethanol. The isomerization of 25(OH)D in solution has implications for calibration of 25(OH)D in clinical measurements, which are discussed.
Palabras clave
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Espectrometría de Masas
/
Vitamina D
/
Calcifediol
/
25-Hidroxivitamina D 2
Tipo de estudio:
Guideline
/
Prognostic_studies
Límite:
Animals
Idioma:
En
Revista:
Anal Bioanal Chem
Año:
2015
Tipo del documento:
Article
País de afiliación:
Estados Unidos