Determination of Quinine and Doxycycline in Rat Plasma by LC–MS–MS: Application to a Pharmacokinetic Study

Abstract

A fast, sensitive, and specific LC-MS-MS method for determination of quinine (QN) and doxycycline (DOX) in rat plasma has been developed and validated. QN, DOX, and cimetidine (internal standard, IS) were extracted from the plasma by protein precipitation. The compounds were separated on a C 18 column with methanol-0.1% aqueous formic acid 70:30 (v/v) as mobile phase at a flow rate of 0.5 mL min -1 (split 1:3). Detection was by positive electrospray ionization (ESI?) in multiple reaction monitoring (MRM) mode, monitoring the transitions 325.0 ? 307.0, 445.0 ? 428.1, and 252.8 ? 159.0, for QN, DOX, and IS, respectively. The analysis was carried out in 2.0 min and the method was linear in the plasma concentration range 5-5,000 ng mL -1 . The mean extraction recoveries for QN, DOX, and IS from plasma were 89.4, 90.5, and 86.3%, respectively. The method was validated for linearity, precision, accuracy, specificity, and stability; the results obtained were within the acceptable range. The proposed method was successfully applied to the determination of QN and DOX in rat plasma samples to support pharmacokinetic studies.

A molecularly imprinted sensor based on an electrochemiluminescent membrane for ultratrace doxycycline determination

“…2 The detection of doxycycline residuals is therefore of great importance. The most commonly used methods were high performance liquid chromatography (HPLC), 3,4 high performance liquid chromatography-mass spectrometry (HPLC-MS) 5 or enzyme-linked immunosorbent assay. 6 But these methods needed complicated sample pretreatment, expensive apparatus and costly operation.…”