Synthesis of 10,11,14,15-13C4- and 14,15-13C2-retinyl acetate

The synthesis of 10,11,14,15-C-13(4)- and 14,15-C-13(2)-retinyl acetate is described. The procedure uses a modified Wittig-Horner synthesis. By using the C-13 isotope, sensitive gas chromatography-combustion-isotope ratio mass spectrometry can be used for analysis in application to human isotope dilution studies.