RESUMO
An analytical methodology for nifedipine quantitation in plasma by on-line solid-phase extraction (SPE) and high-performance liquid chromatography (HPLC) is described. The SPE cartridges contain C2 and the analytes nifedipine and nitrendipine (internal standard) are separated on a C18 column with a mobile phase consisting of acetonitrile-13 mM phosphate buffer pH 7 (65:35, v/v) followed by UV detection at 338 nm. Validation of the method demonstrated good recoveries (>90%), sensitivity (limit of quantification, 2 ng/ml), based on a 500 microl sample volume, accuracy and precision (<5.5% in concentrations greater than the limit of quantitation). This methodology has been used for bioequivalence studies.
Assuntos
Bloqueadores dos Canais de Cálcio/sangue , Cromatografia Líquida de Alta Pressão/métodos , Nifedipino/sangue , Humanos , Padrões de Referência , Reprodutibilidade dos Testes , Sensibilidade e EspecificidadeRESUMO
A comparative study of two analytical methodologies for piroxicam quantitation in plasma by off-line and on-line solid-phase extraction (SPE) and high-performance liquid chromatography (HPLC) is described. The SPE cartridges contained C8 for both extraction methods. The analytes piroxicam and tenoxican (internal standard) were separated on a C18 column with a mobile phase consisting of acetonitrile:20 mM phosphate buffer pH 3.1 (50:50, v/v) followed by UV detection at 360 nm. The validation of the methods demonstrated good recoveries (over 90%), sensitivity (limits of quantification of 0.05 microgram/ml with on-line SPE and 0.1 microgram/ml with off-line SPE, based on a 100 microliters and 200 microliters sample volume, respectively), accuracy and precision (better than 9.5%). Both methodologies have been used for bioequivalence studies.
