Method of preparing D-arabinose labelled with 14C radioisotope or 13C stable isotope

D-arabinose labelled with isotope 14C or 13C is prepared by the oxidation of labelled D-glucose to D-gluconic acid which is then converted to a calcium or barium salt. The oxidation decomposition of the salt proceeds without the separation of intermediate products and in the presence of iron(III) trifluoroacetate as a catalyst. The advantages of the patented method include the decomposition of D-glucose taking place in one reaction mixture, without removal of side products and reaction products. The use of iron(III) trifluoroacetate as a catalyst is more efficient and increases the yield of D-arabinose. (E.S.)