Rapid and sensitive determination of metformin in human urine and serum by capillary electrophoresis with contactless conductivity detection
Abstract
Capillary electrophoresis with contactless conductivity detection has been used for direct determination of the antidiabetic drug metformin in human urine and serum. Metformin is separated in 2 M acetic acid as background electrolyte.
The monitoring of metformin levels in urine is performed on the short separation path under high electric intensity. Under these conditions, the migration time of metformin is 35 s and the limit of detection is 0.3 µM.
Urine samples are 50-fold diluted by 0.01 M HCl and hydrodynamically injected into the capillary in low amount. A method of large volume sample stacking has been developed for the monitoring of plasma levels of metformin.
Serum samples treated by acetonitrile are injected into the capillary in large amount and after switching on the separation voltage the undesirable acetonitrile is forced out of the capillary. This technique reduces the limit of detection to 0.03 µmol/L.