title: Liquid chromatographic determination of ampicillin in bovine and dog plasma by using a tandem solid-phase extraction method.
abstract: The determination of ampicillin in plasma and serum by reversed-phase high-performance liquid chromatography with UV detection suffers from poor selectivity and sensitivity. Currently, the most common approach to overcoming these problems consists of improving the compound's detectability via pre- or postcolumn derivatization. In the method that we describe, however, enhanced selectivity is afforded by sample purification by a tandem solid-phase extraction method (ion-exchange and reversed-phase). This approach permits detection at wavelengths of as low as 210 nm, which results in enhanced sensitivity (detection limit, 0.01 microgram/ml). A second factor that affects selectivity is the addition to the chromatographic eluent of a crown ether to optimize the separation between ampicillin and polar endogenous plasma constituents. This combination of improved sample pretreatment and a more selective chromatographic system in conjunction with internal standardization forms the basis of a new assay for the quantitation of ampicillin in plasma. The overall recovery of ampicillin was 76.4% +/- 4.9% (n = 24), and the within-run and between-run coefficients of variation ranged from 1.6 to 7.2%. The method was applied to pharmacokinetic studies in cows and dogs after intramuscular or oral administration of the drug.
authors.affiliation: Laboratoria voor Medische Biochemie en voor Klinische Analyse, Rijksuniversiteit Gent, Belgium.
authors.forename: H J
authors.initials: HJ
authors.lastname: Nelis
authors.forename: J
authors.initials: J
authors.lastname: Vandenbranden
authors.forename: B
authors.initials: B
authors.lastname: Verhaeghe
authors.forename: A
authors.initials: A
authors.lastname: De Kruif
authors.forename: D
authors.initials: D
authors.lastname: Mattheeuws
authors.forename: A P
authors.initials: AP
authors.lastname: De Leenheer
mesh_terms: D000667:Ampicillin / Q000008:administration & dosage / Q000097:blood* / Q000493:pharmacokinetics; D000818:Animals; D002214:Capsules; D002417:Cattle; D002506:Cephalexin / Q000097:blood; D002851:Chromatography, High Pressure Liquid; D004285:Dogs; D007273:Injections, Intramuscular; D013056:Spectrophotometry, Ultraviolet; D013607:Tablets
chemical_list: D002214:Capsules; D013607:Tablets; D000667:Ampicillin; D002506:Cephalexin