Procedure for the determination of retinol and α-tocopherol in poultry tissues using capillary gas chromatography with solvent venting injection

Abstract

A procedure designed for the determination of retinol (vitamin A) and α-tocopherol (vitamin E) in poultry tissues has been developed. The procedure involves lipid extraction, saponification, solid-phase clean-up and capillary gas chromatography (cGC). Retinol and α-tocopherol were determined separately by cGC–flame ionisation detection using a fused-silica open tubular capillary column, 30 m×0.25 mm I.D. coated with 5% phenylmethylsilicone and with a film thickness of 0.25 μm. Solvent extraction followed by saponification were sufficient to provide a purified extract which was directly analyzed for retinol by cGC in the solvent venting mode. However, in order to accurately determine α-tocopherol by cGC, further purification of the extract by solid-phase extraction was necessary. A silica SPE column was used to remove interfering cholesterol from the extract. α-Tocopherol was analyzed in its derivatized form. Absolute and relative recoveries for both vitamins from spiked samples were evaluated. Absolute and relative recoveries ranging from 80 to 95% were obtained for both compounds. 5α-Cholestane and α-tocopheryl acetate were used as internal standards. Poultry muscle meat and liver tissue were analyzed for their retinol and α-tocopherol content and the peaks detected by cGC were confirmed by cGC–mass spectrometry.