title: Nonaqueous electrochromatography on continuous bed columns of sol-gel bonded large-pore C18 material: separation of retinyl esters.
abstract: A nonaqueous electrochromatographic reversed-phase separation method for retinyl esters using continuous bed columns has been developed. The packing material 7 microm Nucleosil 4,000 angstroms C18 was sol-gel bonded in 180 microm I.D. capillaries. The mobile phase used was 2.5 mM lithium acetate in N,N-dimethylformamide-acetonitrile-methanol (2+7+1, v/v). At 350 V/cm and 30 degrees C, this mobile phase composition gave rise to an electroosmotic flow of 1 mm/s. No Joule heating nor bubble formation were observed even at 625 V/cm (17 microA). With a 36 cm L(eff) column complete separation of the commercially available and synthesized standards (all-trans-retinyl acetate, palmitate, heptadecanoate, stearate, oleoate, and linoleoate) was obtained within 10 min. The within-day and between-day variations of retention times of all-trans-retinyl palmitate were <0.3% relative standard deviation (RSD) (n=3) and <2% RSD (n=6), respectively. The within-day and between-day variations of peak areas were both <2% (both n=3). The columns were used for more than 1 month without degradation. Liver extracts from arctic seal were analyzed.
authors.affiliation: Department of Chemistry, University of Oslo, Norway. line.roed@kjemi.uio.no
authors.forename: L
authors.initials: L
authors.lastname: Roed
authors.forename: E
authors.initials: E
authors.lastname: Lundanes
authors.forename: T
authors.initials: T
authors.lastname: Greibrokk
mesh_terms: D000818:Animals; D020374:Chromatography, Micellar Electrokinetic Capillary / Q000379:methods*; D004952:Esters / Q000302:isolation & purification*; D008099:Liver / Q000737:chemistry; D046048:Seals, Earless; D013696:Temperature; D014801:Vitamin A / Q000737:chemistry* / Q000302:isolation & purification
chemical_list: D004952:Esters; D014801:Vitamin A