HPLC–electrospray mass spectrometric assay for the determination of (R,R)-fenoterol in rat plasma

Abstract

A fast and specific liquid chromatography-mass spectrometry method for the determination of (R,R)-fenoterol ((R,R)-Fen) in rat plasma has been developed and validated. (R,R)-Fen was extracted from 125 µl of plasma using solid phase extraction and analyzed on Atlantis HILIC Silica 3 µm column. The mobile phase was composed of acetonitrile:ammonium acetate (pH 4.1; 20 mM) (85:15, v/v), at a flow rate of 0.2 ml/min. The lower limit of detection (LLOD) was 2 ng/ml . The procedure was validated and applied to the analysis of plasma samples from rats previously administered (R,R)-Fen in an intravenous bolus.

Development and validation of a sensitive LC–MS/MS method for the determination of fenoterol in human plasma and urine samples

“…The extractions were carried out as previously described [17]. Briefly, the 1 ml solid phase extraction (SPE) cartridges (Bond Elut Plexa, Varian, Palo Alto, CA) were preconditioned with 1 ml of methanol, followed by 1 ml of water containing 2% formic acid.…”

“…In addition, these methods involved extensive workup or derivatization. We have recently reported a sensitive LC-MS method for the determination of (R,R′)-Fen in rat plasma after iv administration of the single enantiomer which had a lower limit of quantitation of 2 ng/ml [17]. This method was used as the starting point for the assay reported in this manuscript.…”

Pharmacokinetics and metabolism of (R,R)-methoxyfenoterol in rat

“…The plasma samples obtained after intravenous administration were analysed for (R,R) -MFen and (R,R) -Fen concentrations using a previously described method utilizing solid phase extraction coupled with LC-MS analysis (Siluk et al 2008). The plasma samples obtained after oral administration were analysed for (R,R) -MFen and (R,R) -Fen concentrations using a previously described method employing on-line immunoextraction coupled with LC-MS (Kim et al 2009).…”

“…(R,R) -MFen, (R,R) -Fen and their metabolites were extracted from rat urine using a modified version of the previously described solid phase extraction method (Siluk et al 2008). In brief, a 25 or 5 μl aliquot of urine was acidified with 2% formic acid (20 μl), diluted with 500 μl of ammonium acetate buffer (pH 5.0; 0.1 M) and 20 μl of ritodrine (Rit) (0.2 μg ml -1 in acetonitrile) was added.…”

“…The previously reported LC-MS method for analysis of (R,R) -Fen in rat plasma samples was adopted for the determination of (R,R) -MFen and metabolites in rat urine and for in vitro studies (Siluk et al 2008). In this study, the chromatography was carried out using an Agilent Technologies (Palo Alto, CA) 1100 LC/MSD Series (liquid chromatography-mass selective detector) composed of a vacuum degasser (G1379 A), a quaternary pump (1311A) a thermostated autosampler (G1329 A) and a thermostated column compartment (G1316A).…”