[Study on separation of sulfonamides by capillary high-performance liquid chromatography and electrochromatography]

To establish separation methods of five sulfonamides by using capillary high performance liquid chromatography(mu-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 mu-HPLC at the same condition.

Stationary 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 microL.min-1, pressure was approximately 70 MPa and UV detection wavelength was 254 nm.

Separations on base line have been respectively accomplished for five sulfonamides by mu-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.

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 mu-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 mu-HPLC and CEC. And separation speed of CEC was much faster than that of mu-HPLC. CEC was very fit for rapid separation of sulfonamides.