title: Ion-pair vortex assisted liquid-liquid microextraction with back extraction coupled with high performance liquid chromatography-UV for the determination of metformin in plasma.
abstract: A new sample preparation method, ion-pair vortex assisted liquid-liquid microextraction (VALLME-BE), for the determination of a highly polar anti-diabetic drug (metformin) in plasma sample was developed. The VALLME-BE was performed by diluting the plasma in borate buffer and extracted to 150µL 1-octanol containing 0.2M di-(2-ethylhexyl)phosphoric acid as intermediate phase. The drug was next back-extracted into 20µL of 0.075M HCl solution. The effects of pH, ion-pair concentration, type of organic solvent, volume of extraction phases, ionic strength, vortexing and centrifugation times on the extraction efficiency were investigated. The optimum conditions were at pH 9.3, 60s vortexing and 2min centrifugation. The microextract, contained metformin and buformin (internal standard), was directly injected into a HPLC unit using C1 column (250mm×4.6mm×10µm) and detected at 235nm. The method was validated and calibration curve was linear with r2>0.99 over the range of 20-2000µgL-1. The limits of detection and quantitation were 1.4 and 4.1µgL-1, respectively. The accuracy was within 94.8-108% of the nominal concentration. The relative standard deviation for inter- and intra-day precision was less than 10.8%. The method was conveniently applied for the determination of metformin in plasma samples.
authors: School of Chemical Sciences, Universiti Sains Malaysia, 11800 Penang, Malaysia. Electronic address: anasshishani@gmail.com.
authors: Anas
authors: A
authors: Alshishani
authors: School of Chemical Sciences, Universiti Sains Malaysia, 11800 Penang, Malaysia; Department of Chemistry, Faculty of Science, University of Jordan, 11942 Amman, Jordan.
authors: Ahmad
authors: A
authors: Makahleh
authors: School of Chemical Sciences, Universiti Sains Malaysia, 11800 Penang, Malaysia.
authors: Hui Fang
authors: HF
authors: Yap
authors: School of Chemical Sciences, Universiti Sains Malaysia, 11800 Penang, Malaysia.
authors: Elbaleeq Adam
authors: EA
authors: Gubartallah
authors: School of Pharmaceutical Sciences, Universiti Sains Malaysia, 11800 Penang, Malaysia.
authors: Salizawati Muhamad
authors: SM
authors: Salhimi
authors: School of Chemical Sciences, Universiti Sains Malaysia, 11800 Penang, Malaysia.
authors: Bahruddin
authors: B
authors: Saad
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods; D006801:Humans; D007004:Hypoglycemic Agents / Q000097:blood* / Q000737:chemistry; D059627:Liquid Phase Microextraction / Q000379:methods; D008687:Metformin / Q000097:blood* / Q000737:chemistry; D010755:Organophosphates / Q000737:chemistry*; D014466:Ultraviolet Rays
chemical_list: D007004:Hypoglycemic Agents; D010755:Organophosphates; C007377:di-2-(ethylhexyl)phosphoric acid; D008687:Metformin
keywords: Blood plasma; HPLC; Ion-pair; Metformin; Vortex assisted liquid-liquid microextraction back extraction