Simultaneous determination of cyadox and its metabolites in plasma by high-performance liquid chromatography tandem mass spectrometry

Abstract

Cyadox is a novel antimicrobial growth-promoter of the quinoxalines. For food safety and pharmacokinetic studies, a convenient, sensitive and reproducible LC-ESI-MS/MS method was developed for the simultaneous determination of cyadox and its major metabolites, quinoxaline-2-carboxylic acid, 1,4-bisdesoxycyadox, cyadox-1-monoxide and cyadox-4-monoxide in chicken plasma. Plasma sample was subjected to a simple deproteinisation with acetonitrile. Analysis was performed on a C18 column by detection with mass spectrometry in multiple reaction monitoring mode. A gradient elution program with 0.2% formic acid, methanol and acetonitrile was performed at a flow rate of 0.2 mL/min. The decision limits (CCαs) of five analytes in plasma ranged from 1.0 to 4.0 μg/L, and the detection capabilities (CCβs) were <10 μg/L. Acceptable precision and accuracy were obtained for concentrations over the standard curve range. The extraction recoveries of five analytes were between 87.4 and 93.9% in plasma at the spiked levels of 5 (10)-200 μg/L with the relative standard deviations <10% for each analyte. The developed method demonstrated a satisfactory applicability in real plasma samples.