Screening and identification of azacyclonol and fexofenadine in human urine using LC–MS/MS

Abstract

Abstract Azacyclonol metabolized from fexofenadine and pipradrol are structural isomers and are important biomarkers to determine fexofenadine or pipradrol intake. Detecting these two analytes by liquid chromatography–mass spectrometry (LC–MS) allows for their differentiation from structurally similar compounds. This study aimed to confirm the separation of azacyclonol and pipradrol through different chromatographic conditions in LC–MS. Urine samples were prepared by HLB and were separated in a high-performance reversed phase column. MS detection was achieved using a triple quadrupole mass spectrometer in positive ionization modes. Azacyclonol and pipradrol were differentiated by optimizing the gradient profile using LC–MS. We used a common Poroshell C18 column with acetonitrile and 0.1% acetic acid solution. Azacyclonol and fexofenadine were detected in the urine of patients who took fexofenadine. Fexofenadine is an important biomarker for the determination of azacyclonol and piradrol. LC–MS has been the dominant analytical technology for the quantitative bioanalysis of drugs and metabolites. Although some analytes do not require sufficient separation by LC according to selectivity by LC–MS, sufficient separation by LC is required for the separation of such position isomers.