Simultaneous determination of retinoic acid, retinol, and retinyl palmitate in ram plasma by liquid chromatography

A liquid chromatographic method is described for the simultaneous determination of retinoic acid, retinol, and retinyl palmitate in. ram plasma. Samples of 0.2 mL are extracted with 2-propanol-dichloromethane, the extracts are centrifuged, the supernatants I are collected, evaporated, reconstituted in mobile phase, and analyzed on a C-8 column using two consecutive isocratic elutions with methanol tetrahydrofuran-acetate buffer. Detection is performed at 350 and 325 mn using wavelength change during the run. The method exhibits analytical characteristics well within acceptable limits. Overall recoveries were 73.7% for retinoic acid, 90.2% for retinol, and 87.7% for retinyl palmitate. Precision values, expressed as % relative standard deviation, were in the range of 1.16-6.18%, while limits of detection were in the range of 0.3-10.0 ng/mL for all analytes.