Quantitatively determining impurities in the form of aldehydes and ketones in glycerol processing for the production of drugs, comprises reacting the glycerol containing the impurities in a sample solution with a derivatizing reagent and determining the amount of derivatized impurities, where the derivatizing reagent is O-(2,3,4,5,6-pentafluorobenzyl)-hydroxylamine hydrochloride； the derivatization is carried out in the presence of a solubilizer in the form of a polar organic solvent； and a separation by liquid chromatography and a detection of the separated impurities are carried out.
