Abstract: The glucuronide conjunction of N-(4-ethoxyphenyl)-2-hydroxyl-benza-mide, 3H-1,2-dihydro-2-(4-methyl-phenylamino)methyl-1-pyrrolizinone (SFZ-47) and bilecoll were were analysed by electrospray ionization (ESI) quadrupole time-of-flight mass spectrometry in the negative - anions were produced in high yield, some common fragmentation patterns w found to be closely related to the glucuronide. The fragment m/z 175.0241 which is respond to glucuronide was the common to all the compounds under study and the fragment m/z 113.0238 was another diagnostic fragment ion, which was produced by loss of H 2O and CO 2 from m/z 175.0241. These fragmentation patterns could be used to identify the glucuronide conjunction of drugs.