Resolution, quantification and confirmation of betamethasone and dexamethasone in equine plasma by liquid chromatography/tandem mass spectrometry

Abstract

This method describes the simultaneous separation, identification, quantification and confirmation of betamethasone (BTM) and dexamethasone (DXM) in equine plasma by liquid chromatography (LC) integrated with multidimensional tandem mass spectrometry. Analytes were directly extracted from equine plasma by methyl tert-butyl ether (MTBE). The residues were reconstituted with sample solvent. LC separation of the analytes was performed on a Hypercarb column using acetonitrile/water/formic acid (95:5:0.5, v/v/v) as the mobile phase. Sample screening, quantification and confirmation were performed in multiple reaction monitoring (MRM) mode. The method was linear over the concentration range of 0.1-75 ng/mL for both analytes. Limit of detection (LOD) was 50 pg/mL and that of quantification (LOQ) was 100 pg/mL for both analytes. The limit of confirmation (LOC) for the presence of BTM or DXM by MRM was 0.5 ng/mL. The intra-and inter-day precisions expressed as coefficient of variation (CV) for quantification of DXM and BTM from 0.1 to 50 ng/mL were less than 7% and the accuracy was in the range of 97-105%. This method is capable of distinguishing BTM from DXM when both analytes are simultaneously present in equine plasma. Measurement uncertainty for both analytes was estimated at less than 16%. The method is rapid, specific, selective, sensitive, simple and reliable. The importance of this method is its usefulness in directly identifying and differentiating BTM from DXM without derivatization.

Betamethasone Pharmacokinetics After Two Prodrug Formulations in Sheep: Implications for Antenatal Corticosteroid Use

“…By using a larger sample volume, we were able to reduce the assay lower limit of quantification of 2 ng/ml, reported by Tamvakopoulos et al (2002), to 0.1 ng/ml. During the preparation of this article, two other methods describing LC/ MS/MS analysis of betamethasone in plasma were published (Taylor et al, 2004;Luo et al, 2005). These methods monitor different daughter ions in tandem mass spectrometry for betamethasone and make use of longer liquid-liquid extraction-based sample preparation methods.…”

Determination of dexamethasone and dexamethasone sodium phosphate in human plasma and cochlear perilymph by liquid chromatography/tandem mass spectrometry

“…HPLC with tandem mass spectrometric detection (LC-MS/MS) has been demonstrated to provide high sensitivity for the quantitative determination of drugs and metabolites in biological fluids. Some LC-MS/MS methods for measuring Dex in biological samples have been reported [3][4][5][6], in which a relatively large volume of sample was required (>200 l). For Dex SP analysis, there is one published HPLC-UV-MS method that has been used to report the analysis of Dex SP in cochlear perilymph of guinea pigs [7], in which HPLC with UV detection was used for Dex SP quantification and MS for Dex SP identification.…”

Dexamethasone quantification in dried blood spot samples using LC–MS: The potential for application to neonatal pharmacokinetic studies

“…The paucity in data is at least in part due to practical difficulties and ethical considerations surrounding blood collection in neonates. There are a number of reports on the quantification of dexamethasone in blood plasma using liquid chromatography coupled with UV [6][7][8][9][10], mass spectrometry [11][12][13][14][15], or fluorescence detection [16,17], gas chromatography with mass spectrometry [18,19] and immunological [20]. However, most of these assays require a relatively large blood volume (typically >0.5 ml) to generate a sufficient plasma volume for analysis.…”