Objective To establish a high-performance liquid chromatography-mass spectrometry(LC//MS)-based method for efficient determination of melamine in urinary calculi in children taking melamine-contaminated formula milk powder.Methods LC/MS was employed to determine the contents of melamine in urinary calculi surgically removed from 17 children with a history of taking melamine-contaminated milk powder and in 4 samples of uric acid stone from adults.The positive ionization mode of electro-spray ionization sourc...