Quantification of retinoid compounds by supercritical fluid chromatography coupled to ultraviolet diode array detection

Liposoluble vitamins are widely analyzed due to their significant antioxidant activity. Quantification by liquid or gas chromatography is often time consuming and requires sample treatments prior to the analysis. Supercritical fluid chromatography (SFC), especially with the developments of new commercial systems, is nowadays considered as a credible alternative to standard chromatography. It provides a reduced acquisition time as well as sensitivity similar to that of liquid chromatography. To illustrate the new capabilities of SFC, six organic compounds related to the vitamin A family, all-trans-retinal, all-trans-retinol, all-trans-retinoic acid, retinyl propionate, retinyl acetate, and all-trans-retinyl palmitate, were analyzed and quantified. The choice of the column chemistry, co-solvent, the linearity and reproducibility of the method, and the matrix effect are discussed in detail. Best separation was finally obtained using a diphenyl column, with an excellent linearity over three orders of magnitude and limits of quantification in the low picomole range. Finally, the method was used for the quantification of retinyl palmitate in a pharmaceutical product with minimal sample preparation.