Method of preparing D-[U-14C?erythrose and D-[U-14C?threose

D-[U-14C?erythrose and D-[U-14C?threose are the result of the reaction of D-[U-14C?arabinose and D-[U-14C?xylose, respectively, with 4-nitrophenyl hydrazine. In the reaction, D-[U-14C?aldopentose 4-nitrophenyl hydrazone is produced as an intermediate product. It is degraded by oxidation with hydrogen peroxide. The degradation takes place in an alkaline medium to the corresponding D-[U-14C?aldotetrose under the catalytic action of molybdate ions. The resulting products are chromatographically separated. Examples are given of the preparation of D-[U-14C?erythrose and D-[U-14C?threose. The separated labelled erythrose and threose are stored directly on dry chromatographic paper in sealed dark containers. The advantages of this method of preparing the compounds include its ease, easy availability of labelled aldopentose, and the possible regeneration of 30 to 45% of the initial aldopentose during the reaction. The reaction takes place in one test tube. (E.S.)