Retinyl esters chromatographic separation

Furr, H.C. Amedee-Manesme, O. Olson, J.A. Gradient reversed-phase high-performance liquid chromatographic separation of naturally occurring retinoids. J.Chromatogr., 1984, 309, 299-307 [gradient rat human pig liver kidney extracted retinyl esters, tretinoin, vitEunin A]... 

Reversed-phase packing materials (Cig and Cg) are utilized especially for the separation of the different retinyl esters and for combined vitamin A and carotenoid mixtures such as those in food extracts and clinical samples. Most semiaqueous mobile phases, consisting of mixtures of methanol or acetonitrile and water, result in chromatographic runs of more than 1 h to elute retinyl stearate. Gradient elution shortens this elution time but results in a loss of separation of two predominant esters, retinyl palmitate and retinyl stearate. More recently, isocratic non-aqueous reversed-phase (NARP) conditions with an acetonitrile-dichloromethane mixture resulted in a successful separation of the different esters within 15 min. The big advantage of NARP conditions over semiaqueous systems is the increased solubility of lipids. To compensate for this increased affinity of the compounds of low polarity for the eluent, highly retentive stationary phases are recommended. 

In order to correct for phytofluene in plasma or serum extracts, a correction formula consequently has been used in several of the assays cited in Table V. Alternatively, chromatographic separation of retinol and retinyl ester from phytofluene can be readily carried out on silicic acid or alumina columns (Garry etaL, 1970 Pollack a/., 1973 Loerch and Underwood, 1982) or on thin-layer plates of silica gel (Drujan et al, 1968). In addition, unidentified fluorescent pigment that increases the apparent retinol value of serum by as much as fourfold has also been found in the serum of pregnant Indian women (Sivakumar, 1977). 

MGM De Ruyter, AP De Leenheer. Effect of silver ions on the reversed-phase high performance hquid chromatographic separation of retinyl esters. Anal Chem 51 43-46, 1979. 

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