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Determination of Linezolid in Human Plasma by High-Performance Liquid Chromatography With Ultraviolet Detection

Cattaneo, Dario PhD*; Baldelli, Sara ChemD*; Conti, Francesca BiotechnolD*; Cozzi, Valeria BiolSciD*; Clementi, Emilio MD*†

doi: 10.1097/FTD.0b013e3181d5eeee
Short Communication

A high-performance liquid chromatographic method for the determination of linezolid in human plasma was developed and validated. After precipitation of plasma proteins with perchloric acid, the protein-free supernatant was separated by isocratic reverse-phase chromatography on a X Bridge C18 column. The mobile phase consisted of a mixture of phosphoric acid 0.05%: acetonitrile (75:25, v/v) with a flow rate of 1 mL/min. The column elute was monitored at 254 nm. The method was linear from 0.2 to 48 mg/L (mean r2 = 0.9996, n = 10). The observed intra- and inter-day assay imprecision ranged from 2.83% to 8.16% (18.80% at the lower limit of quantification); inaccuracy varied between -0.33% and 8.18%. Mean drug recovery was 99.8% for linezolid and 90.0% for the internal standard (para-toluic acid). The method was found to be precise and accurate and suitable for therapeutic drug monitoring of linezolid in routine clinical practice.

From the *Unit of Clinical Pharmacology, Department of Preclinical Sciences, University Hospital “Luigi Sacco,” Università di Milano, Milan, Italy; and †E. Medea Scientific Institute, Bosisio Parini, Italy.

Received for publication October 8, 2009; accepted January 26, 2010.

Correspondence: Dario Cattaneo, PhD, Department of Preclinical Sciences LITA-Vialba, University of Milano, via GB Grassi 74, 20157 Milano, Italy (e-mail:

© 2010 Lippincott Williams & Wilkins, Inc.