Ultrasensitive determination of NE-100, a novel sigma ligand, in human plasma by liquid chromatography and electrospray ionization tandem mass spectrometry combined with a column-switching technique

Abstract

For the highly sensitive and selective determination of NE-100, a novel sigma ligand, at levels of low picogram per milliliter of human plasma, a method with excellent reliability employing liquid chromatography (LC)–electrospray ionization (ESI) tandem mass spectrometry (MS–MS) combined with a column-switching technique has been developed. The method involves the use of a stable isotope labeled compound as the internal standard (I.S.), liquid–solid extraction of a plasma specimen with a C 8 cartridge, automated on-line clean-up on a short trapping column, subsequent separation on a micro-bore C 18 column and detection with ESI-MS–MS using m/z 356 ([M+H] +) as a precursor ion and m/z 105 as a product ion in a selected reaction monitoring mode. The detection and the quantification limits of NE-100 in plasma were 0.5 pg/ml with a signal-to-noise ratio ( S/ N) of 3 and 2.3 pg/ml, respectively, with an S/ N of 21. The good linearity of the calibration graph was obtained in the range of 2.3∼907.0 pg/ml with excellent reliability. The developed method was applied to the determination of NE-100 in plasma obtained from the clinical trail.