Field-Amplified on-line Sample Stacking for Separation and Determination of Adefovir and Tenofovir Using Capillary Electrophoresis

摘要

An on-line sample stacking method known as field amplified sample stacking, using hydroxypropylmethyl cellulose as electro-osmotic flow suppressant, was developed for separation and identification of adefovir and tenofovir for the first time. A water plug (hydrodynamic injection for 15 s. 2.0 psi) was added to the system prior to the loading of sample (electrokinetic injection at cathode end (14.6 kV, 20 s)) in the capillary (80 cm x 75 μm). The separation was performed using phosphate solution containing 0.3 % hydroxypropylmethyl cellulose and measured at 18 kV and 214 nm. Comparing with the conventional capillary electrophoresis, the signal enhancement factor was found to be 146 for adefovir (LOD = 2.67 ng mL~(-1)) and 137 for tenofovir (LOD = 3.22 ng mL~(-1)) (S/N = 3). The proposed method has potential application in pharmacokinetics and can reach detection limits comparable to mass spectrometry, a more complicated and costly procedures.