The method consists in dissolving of a test portion in chloroform, extracting of free glycerol from this sulution with acetic acid solution, oxidizing of 1-monoglycerides in the chloroform solution by an excess of periodic acid solution, adding of potassium iodide and titration of the liberated iodine with a sodium thiosulfate standard volumetric solution. Oxidation of free glycerol in the aqueous solution by an excess of periodic acid solution, adding of potassium iodide titration of the liberated iodine with a sodium thiosulfate standard volumetric solution.