Objective:To improve the method for determination of ADA in body fluids by catalytic spectrophotometry.Methods:Based on Berthelot,the amount of released NH 3 per minute was determined and the activity of ADA was calculated indirectly.Results:The relative standard deviation(RSD)of within groups and between groups were found to be 1.16%~2.17%,2.49%~3.25% respectively.The determination condition had been studied through orthogonal designs and one factor design,an optimum contidion had been obtained.Contrasted to document,the reaction time was cut down 40 minutes and the amount of reagent was redu...