Determination of moxonidine in human plasma by liquid chromatography–electrospray ionisation–mass spectrometry

Abstract

A sensitive and specific liquid chromatography–electrospray ionisation–mass spectrometry (LC–ESI–MS) method has been developed and validated for the identification and quantification of moxonidine in human plasma. After the addition of clonidine–HCl, the internal standard (IS) and sodium hydrogen carbonate, plasma samples were extracted using 5 mL ethyl acetate. The compounds were separated on a Lichrospher ODS (5 μm, 250 mm × 4.6 mm) column using an elution system of 10 mmol/L ammonium acetate buffer–methanol (20:80 v/v) as the mobile phase. Analytes were determined using electrospary ionization in a single quadrupole mass spectrometer. LC–ESI–MS was performed in the selected-ion monitoring (SIM) mode using target ions at m/ z: 242.2 for moxonidine and m/ z: 230.1 for the IS. The method has shown to be sensitive and specific by testing six different blank plasma batches. Linearity was established for the range of concentrations 0.01976–9.88 ng/mL with a coefficient of correlation ( r) of 0.9999. The lower limit of quantification (LOQ) was identifiable and reproducible at 0.01976 ng/mL. The method has been successfully applied to study the pharmacokinetics of moxonidine in healthy male Chinese volunteers.