This study aimed to develop a menadione (MD) determination method employing liquid chromatography-tandem mass spectrometry (LC-MS/MS) using a pseudo multiple reaction monitoring (MRM) technique, wherein two quadrupoles are used to monitor the same ion. Detection limits of 40 and 2 pg were obtained for MD and its deuterium-labeled form, respectively, whereas MD intra- and inter-assay coefficient of variation values were determined as 5.4 - 8.2%, with the corresponding recoveries equaling 90.5 - 109.6%. The developed method enables determination of MD in urine, plasma, cell extract, and culture media, demonstrating that pseudo multiple reaction monitoring can achieve quantification of compounds forming no suitable product ions, such as MD.
Keywords: LC-MS/MS; Menadione; pseudo MRM; vitamin K.