Liquid chromatography tandem mass spectrometry method for the estimation of modafinil in human plasma
A rapid, selective and sensitive high performance liquid chromatography–tandem mass spectrometry method (LC-MS/MS) was developed and validated for the estimation of modafinil in human plasma. Modafinil and the internal standard (ISTD), Modafinil-D5, were extracted from plasma samples using solid phase extraction with Agilent® Bond Elut Plexa cartridges. Chromatographic separation was performed on a Ascentis® C18 column (150mm×4.6mm, 5µm) using methanol: 2mM ammonium acetate: glacial acetic acid (35:65:0.1% v/v/v) as the mobile phase at a flow rate of 1.0 mL/min. Detection of modafinil and modafinil-D5 was achieved by tandem mass spectrometry with an electrospray ionization (ESI) interface in positive ion mode. The calibration curves were linear over the range of 30.8 to 8022.1 ng/mL. The method has a lower limit of quantitation (LLOQ) of 30.8 ng/mL and the limit of detection (LOD) achieved of 1 ng/mL for modafinil, based on a signal to noise ratio of 10. The intra- and inter-day precisions were within 3.1%, while the accuracy was within ±3.3% of nominal values. No matrix effect was observed in this method.
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