title: Solid-phase extraction protocol for isolating retinol-d4 and retinol from plasma for parallel processing for epidemiological studies.
abstract: Solid-phase extraction permits the parallel processing of samples in large numbers. We have applied this technique to the isolation of retinol isotopomers from plasma of humans participating in a study of vitamin A stable isotope dilution. The isotopomers were analyzed by gas chromatography/mass spectrometry. The extraction involves the separation of retinol from its aqueous matrix with a C18 silica-based sorbent followed by removal of lipid contaminants with an aminopropyl silica-based sorbent. Overall recovery of retinol from plasma was 47.2% +/- 1.8%. Purity of the retinol isolated from plasma is comparable with that obtained with a single HPLC method. This method permits the preparation of 32 samples per day by one analyst. Elimination of the need for HPLC permits sample preparation in the field with a minimum of equipment and technical skill.
authors.affiliation: Department of Nutrition, University of California, Davis 95616-8669.
authors.forename: S R
authors.initials: SR
authors.lastname: Dueker
authors.forename: J M
authors.initials: JM
authors.lastname: Lunetta
authors.forename: A D
authors.initials: AD
authors.lastname: Jones
authors.forename: A J
authors.initials: AJ
authors.lastname: Clifford
mesh_terms: D000097:Acetonitriles; D000327:Adsorption; D002851:Chromatography, High Pressure Liquid; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D007201:Indicator Dilution Techniques; D008297:Male; D008875:Middle Aged; D011437:Propylamines; D012822:Silicon Dioxide; D014801:Vitamin A / Q000097:blood*
chemical_list: D000097:Acetonitriles; D011437:Propylamines; D014801:Vitamin A; D012822:Silicon Dioxide; C032159:acetonitrile