title: Method for the simultaneous determination of retinol and beta-carotene concentrations in human tissues and plasma.
abstract: To understand differential tissue distribution of retinoids and carotenoids, as it might influence biological processes in humans, we developed and demonstrated a method for measuring them in selected human tissues. The method includes internal standards and a secondary reference standard to eliminate the need for external standard calibration and to minimize sample-handling errors. Tissues were digested (saponified) in ethanolic KOH. Retinol and beta-carotene were extracted with organic solvent containing internal standards. Analytes were separated using isocratic liquid chromatography and quantified at 325 nm for retinol and 450 nm for beta-carotene. Plasma was analyzed in a similar way but without saponification. Retinal-O-ethyloxime and beta-apo-12'-carotenal-O-t-butyloxime served as internal standards. Plasma, breast, and fat from breast surgery patients and colon, liver, muscle, and fat from colon surgery patients were analyzed. Within-day relative standard deviations (RSDs) for plasma were <0.04 for beta-carotene and <0.03 for retinol, between-day RSDs were <0.05 for beta-carotene and <0.04 for retinol. Saponification ensured complete extraction of retinol and beta-carotene and removal of triglycerides that "foul" chromatographic columns. It seems retinol and beta-carotene concentrations in tissues and blood of cancer patients are the same or higher than those in corresponding tissues of patients without these cancers.
authors.affiliation: Department of Nutrition, University of California at Davis, 95616, USA.
authors.forename: Jennine M
authors.initials: JM
authors.lastname: Lunetta
authors.forename: Rebecca A
authors.initials: RA
authors.lastname: Zulim
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Dueker
authors.forename: Yumei
authors.initials: Y
authors.lastname: Lin
authors.forename: Vicky
authors.initials: V
authors.lastname: Flaig
authors.forename: Philip D
authors.initials: PD
authors.lastname: Schneider
authors.forename: Bruce M
authors.initials: BM
authors.lastname: Wolfe
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Clifford
mesh_terms: D000328:Adult; D000368:Aged; D001774:Blood Chemical Analysis / Q000379:methods; D001943:Breast Neoplasms / Q000097:blood / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D003110:Colonic Neoplasms / Q000097:blood / Q000737:chemistry; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012015:Reference Standards; D013053:Spectrophotometry; D014018:Tissue Distribution; D014801:Vitamin A / Q000032:analysis* / Q000097:blood* / Q000592:standards; D019207:beta Carotene / Q000032:analysis* / Q000097:blood* / Q000592:standards
chemical_list: D019207:beta Carotene; D014801:Vitamin A