Examine by thin-layer chromatography (2.2.27), using silica gel G R as the coating substance.Test solution. Dissolve 50 mg of the substance to be examined in water R and dilute to 20 ml with the same solvent.
Reference solution. Dissolve 50 mg of sorbitol/mannitol CRS in water R and dilute to 20 ml with the same solvent.
Apply separately to the plate 2 ml of each solution. Develop over a path of 17 cm using a mixture of 10 volumes of water R, 20 volumes of ethyl acetate R and 70 volumes of propanol R. Allow the plate to dry in air and spray with 4-aminobenzoic acid solution R. Dry the plate in a current of cold air until the acetone is removed. Heat the plate at 100 �C for 15 min. Allow to cool and spray with a 2 g/l solution of sodium periodate R. Dry the plate in a current of cold air. Heat the plate at 100 �C for 15 min. The principal spot in the chromatogram obtained with the test solution is similar in position, colour and size to the principal spot in the chromatogram obtained with the reference solution.
2 juli 1999