Determination of metoprolol enantiomers in human plasma and saliva samples utilizing microextraction by packed sorbent and liquid chromatography–tandem mass spectrometry

Abstract

A sensitive, accurate and reliable bioanalytical method for the enantioselective determination of metoprolol in plasma and saliva samples utilizing liquid chromatography-electrospray ionization tandem mass spectrometry was developed and validated. Human plasma and saliva samples were pretreated by microextraction by packed sorbent (MEPS) prior to analysis. A new MEPS syringe form with two inputs was used. Metoprolol enantiomers and internal standard pentycaine (IS) were eluted from MEPS sorbent using isopropanol after removal of matrix interferences using aliquots of 5% methanol in water. Complete separation of metoprolol enantiomers was achieved on a Cellulose-SB column (150 × 4.6 mm, 5 μm) using isocratic elution with mobile phase 0.1% ammonium hydroxide in hexane-isopropanol (80:20, v/v) with a flow rate of 0.8 mL/min. A post-column solvent-assisted ionization was applied to enhance metoprolol ionization signal in positive mode monitoring (+ES) using 0.5% formic acid in isopropanol at a flow rate of 0.2 mL/min. The total chromatographic run time was 10 min for each injection. The detection of metoprolol in plasma and saliva samples was performed using triple quadrupole tandem mass spectrometer in +ES under the following mass transitions: m/z 268.08 → 72.09 for metoprolol and m/z 303.3 → 154.3 for IS. The linearity range was 2.5-500 ng/mL for both R- and S-metoprolol in plasma and saliva. The limits of detection and quantitation for both enantiomers were 0.5 and 2.5 ng/mL respectively, in both matrices (plasma and saliva). The intra- and inter-day precisions were presented in terms of RSD values for replicate analysis of quality control samples and were <5%; the accuracy of determinations varied from 96 to 99%. The method was able to determine the therapeutic levels of metoprolol enantiomers in both human plasma and saliva samples successfully, which can aid in therapeutic drug monitoring in clinical laboratories. Copyright © 2016 John Wiley & Sons, Ltd.

Current trends on microextraction by packed sorbent – fundamentals, application fields, innovative improvements and future applications

“…The same researchers used the CDF-MEPS approach to assay new sorbents and their protein clean-up properties, namely polymer monoliths 201 and the poly(ethylene glycol) functionalization of monolithic poly(divinyl benzene). 202 The CDF-MEPS was also used by Elmongy et al 60 to extract metoprolol enantiomers from human plasma and saliva. In this case, the CDF path was used as the inlet to load the samples.…”

Recent Trends in Microextraction Techniques Employed in Analytical and Bioanalytical Sample Preparation

“…In fact, the main critical point during extraction relates to the reproducibility of the flow rate (generally µL s −1 ) used in the different steps (Figure 1). A MEPS syringe and a one-way check valve [43] was used for the realization of automated or semi-automated MEPS extraction, both for on-line and off-line instrument configurations. n.r.…”

Screening of Drugs in Saliva

“…Minor sample preparation procedures are required in case of saliva samples. Micro-extraction by packed sorbent (MEPS) is a miniaturized technique that can provide highly efficientextraction of target analytes using a programmable automatic pipette eVol® which facilitate handling and maintain the reproducibility of the method [4,16].…”