CE with direct sample injection for the determination of metformin in plasma for type 2 diabetic mellitus: An adequate alternative to HPLC.

We developed a simple and selective CE with UV detection at 233 nm for the analysis of metformin in plasma based on direct sample injection without any pretreatment. The sample was employed with an electrokinetic injection of 10 kV for 100 s. CE separation of metformin from biological matrix was performed at 25 degrees C using a BGE consisting of 25 mM Tris buffer at pH 4.0. The linear range of the CE method for the determination of metformin in plasma was over the range of 0.1-2.0 mug/mL; the LOD of the drug in plasma (S/N = 3; injection 10 kV, 100 s) was 30 ng/mL. Data by CE were compared with the results obtained by a validated HPLC method. CE assay of metformin exhibited a very good correlation (r(2 )= 1) with respect to HPLC. CE determination of metformin is a robust, sensitive, and reproducible method with the advantage over HPLC of being fast, without prior extraction, or precipitation of proteins, also enabling quick assessment of metformin for pharmacokinetic and clinical studies.