A simple and sensitive method is studied to determine sulfadiazine in pure form. The method utilizes a liquid ion exchange reaction based upon forming an ion-pair association complex for SDz with Ni(II) in the presence of HCl and non-ionic surfactant Triton X-100. The maximum wavelength was 291nm. The optimum condition effect on the separation method was studied: temperature 90°C, heating time 15min., the concentration of Ni(II) was 50μg/mL, and the best surfactant was TritonX-100. The reaction kinetics were studied by using the initial rate method. The calibration curve was linear over the concentration range of 1-100μg/mL with LOD of 5.09 μg/mL and LOQ of 15.43μg/mL.