title: Sensitive assay for measuring amoxicillin in human plasma and middle ear fluid using solid-phase extraction and reversed-phase high-performance liquid chromatography.
abstract: We developed a sensitive assay to measure amoxicillin in human plasma and middle ear fluid (MEF) using solid-phase extraction and reversed-phase HPLC. Amoxicillin and cefadroxil, the internal standard, were extracted from 50-200 microliters of sample with Bond Elut C18 cartridges. The extract was analyzed on a 15 cm x 2 mm, 5 micron Keystone MOS Hypersil-1 (C8) column with UV detection at 210 nm. The mobile phase was 6% acetonitrile in 5 mM phosphate buffer (pH = 6.5) and 5 mM tetrabutylammonium. The average absolute recovery of amoxicillin and cefadroxil were 91.2 +/- 16.6% and 91.0 +/- 6.8%, respectively. The limit of quantitation was 0.125 microgram/ml with 200 microliters sample size. The linear range was from 0.125 to 35.0 micrograms/ml with correlation coefficients greater than 0.999. These analytic conditions produced a highly sensitive amoxicillin assay in human body fluids without derivatization.
authors: Department of Pharmacy Practice, College of Pharmacy and School of Medicine, University of Minnesota, Minneapolis, USA.
authors: Z
authors: Z
authors: Yuan
authors: H Q
authors: HQ
authors: Russlie
authors: D M
authors: DM
authors: Canafax
mesh_terms: D000097:Acetonitriles; D000658:Amoxicillin / Q000032:analysis* / Q000097:blood* / Q000493:pharmacokinetics; D001826:Body Fluids / Q000737:chemistry; D002138:Calibration; D002434:Cefadroxil / Q000032:analysis / Q000097:blood / Q000493:pharmacokinetics; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D003902:Detergents; D004432:Ear, Middle; D005122:Exudates and Transudates / Q000737:chemistry*; D006801:Humans; D010034:Otitis Media with Effusion / Q000378:metabolism; D000644:Quaternary Ammonium Compounds; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013056:Spectrophotometry, Ultraviolet
chemical_list: D000097:Acetonitriles; D003902:Detergents; D000644:Quaternary Ammonium Compounds; D002434:Cefadroxil; D000658:Amoxicillin; C009405:tetrabutylammonium; C032159:acetonitrile