[Separation of salicylic acid drugs by aqueous and nonaqueous capillary electrophoresis with conductance detector].

AIM: To develop a method for separating salicylic acid drugs by aqueous and nonaqueous capillary electrophoresis with conductance detector.

METHODS

Fused-silica capillary (55 cm x 50 microns 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.

RESULTS

High 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.

CONCLUSION

The 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.