title: Direct determination of metformin in urine by adsorptive catalytic square-wave voltammetry.
abstract: A new adsorptive catalytic voltammetric method for voltammetric determination of metformin based on the catalytic hydrogen evolution reaction at a hanging mercury drop electrode was developed. The electrode reaction was analyzed under conditions of linear sweep voltammetry (LSV), differential pulse voltammetry (DPV) and Osteryoung-type square-wave voltammetry (SWV). The peak current depends on pH of the medium, concentration and chemical composition of the buffer solution, and instrumental parameters. The optimal conditions for quantitative determination were obtained in an acetate buffer at pH 4.7. The voltammetric procedure was characterized with respect to the repeatability, precision and the recovery. The detection and quantification limits were found to be 1.8 x 10(-8) and 5.9 x 10(-8) mol l(-1) for SWV, 3.2 x 10(-8) and 1.0 x 10(-7) mol l(-1) for DPV, and 7.7 x 10(-8) and 2.5 x 10(-7) mol l(-1) for LSV, respectively. The SW voltammetric method, as the most sensitive one, was applied for determination of metformin in human urine. The voltammetric method has been validated by using HPLC with UV detection.
authors.affiliation: Department of Instrumental Analysis, University of Łódź, Pomorska 163, 90-236 Łódź, Poland. skrzpek@uni.lodz.pl
authors.forename: Sławomira
authors.initials: S
authors.lastname: Skrzypek
authors.forename: Valentin
authors.initials: V
authors.lastname: Mirceski
authors.forename: Witold
authors.initials: W
authors.lastname: Ciesielski
authors.forename: Adam
authors.initials: A
authors.lastname: Sokołowski
authors.forename: Robert
authors.initials: R
authors.lastname: Zakrzewski
mesh_terms: D000085:Acetates / Q000737:chemistry; D000327:Adsorption; D002021:Buffers; D002384:Catalysis; D002851:Chromatography, High Pressure Liquid; D004563:Electrochemistry / Q000379:methods; D004566:Electrodes; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007004:Hypoglycemic Agents / Q000737:chemistry / Q000652:urine*; D008687:Metformin / Q000652:urine*; D015394:Molecular Structure; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013056:Spectrophotometry, Ultraviolet