Determination of metformin in plasma by high-performance liquid chromatography after ultrafiltration.
A rapid high-performance liquid chromatography (HPLC) method was developed for determination of metformin, an oral antidiabetic agent, in plasma. Sample preparation entailed a 30-min centrifugation of plasma through a micron filter with direct injection of the protein-free ultrafiltrate into an HPLC system consisting of a cation-exchange extraction column (7.5x4.6 mm), a column switching valve, and a cation-exchange analytical column (250x4.6 mm). The eluent was monitored at 232 nm. Metformin was well resolved at a retention time of about 5 min. There was less than 2% loss of metformin during ultrafiltration and good linearity was established from 0.10 to 40 mg/l of metformin hydrochloride. The lower limit of quantitation was about 0.05 mg/l, at which concentration the signal-to-noise was above 10. The intra- and inter-assay coefficients of variation at plasma concentrations of metformin hydrochloride between 0.25 and 25 mg/l were typically 0.8-1.4% and 3.5-6.4%, respectively. This method offers a rapid sample preparation time and achieves excellent sensitivity without resorting to extraction and evaporation techniques.
Vesterqvist
O
O
Clinical Laboratory, Bristol-Myers Squibb Pharmaceutical Research Institute, Princeton, NJ 08540, USA.
Nabbie
F
F
Swanson
B
B
D000925:Anticoagulants; D001798:Blood Proteins / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D004492:Edetic Acid; D005615:Freezing; D006493:Heparin; D006801:Humans; D007004:Hypoglycemic Agents / Q000097:blood*; D008687:Metformin / Q000097:blood*; D012680:Sensitivity and Specificity; D014462:Ultrafiltration
D000925:Anticoagulants; D001798:Blood Proteins; D007004:Hypoglycemic Agents; D006493:Heparin; D008687:Metformin; D004492:Edetic Acid