Abstract: AimTo establish separation methods of five sulfonamides by using capillary high performance liquid chromatography(μ-HPLC) and electrochromatography. The effect of mobile phase varies such as methanol content, pH, buffer solution concentration and voltage on their chromatographic behavior and electroosmesis flow was investigated. Capillary electrochromatography(CEC) was compared with μ-HPLC at the same condition.MethodsStationary phase was ODS, mobile phase was methanol and 2 mmol·L^-1 H₃PO₄ buffer solution (pH 3.0-7.0), voltage was 0- -15 kV, flow rate was 10 μL·min^-1, pressure was approximately 70 MPa and UV detection wavelength was 254 nm. ResultsSeparations on base line have been respectively accomplished for five sulfonamides by μ-HPLC with mobile phase of methanol-2 mmol·L^-1 H₃PO₄ buffer solution (30∶70) at pH 5.0 in 67 min, and CEC with the same mobile phase at -5 kV voltage in 25 min. Conclusion Electroosmesis flow of CEC decreased with the increase in methanol content, buffer solution concentration, increased with the increase in voltage and increase slightly with the increase in pH of mobile phase. Retention values (k) of solutes to be examined decreased with increasing methanol content of mobile phase in μ-HPLC and CEC. Retention values (k) of solutes increased slightly with increasing buffer solution concentration, decreased with increasing voltage in CEC. Trimethoprim(TMP) decreased obviously with increasing voltage in CEC. The effect of pH of mobile phase on retention values (k) was more complex. Five sulfonamides were separated at the same mobile phase condition by μ-HPLC and CEC. And separation speed of CEC was much faster than that of μ-HPLC. CEC was very fit for rapid separation of sulfonamides.