Abstract: AimTo develop a method for separating salicylic acid drugs by aqueous and nonaqueous capillary electrophoresis with conductance detector. MethodsFused-silica capillary (55 cm×50 μm ID) was used. The effects of concentration and pH of the running buffer, running voltage and injection time were studied. Salicylic acid (SA), acetylsalicylic acid (ASA) and sulfosalicylic acid (SSA) can be separated in a 10 mmol·L^-1 Tris-30 mmol·L^-1 H₃BO₃ buffer (pH 8.0), the separation voltage and injection time were 24 kV and 10 s, respectively. But tailing peaks appeared. In order to improve the separation efficiency and the sensitivity, ethanol was used as nonaqueous solvent. ResultsHigh sensitivity and resolution for SA, ASA and SSA were obtained in ethanol media, and there was excellent linearity between peak area and concentration of the analytes in the concentration range of 0.05-100 mg·L^-1, 5.0-250 mg·L^-1 and 0.08-100 mg·L^-1 for SA, ASA and SSA, respectively. All the correlation coefficients were over 0.995. ConclusionThe analysis of SA and ASA in aspirin tablets was tried and good results were obtained in ethanol media. There was higher sensitivity and separation efficiency than in aqueous media.