Solid–phase extraction (SPE)

In the present paper, the authors described a novel Liquid chromatography–tandem mass spectrometry (LC–MS/MS) method for the determination of montelukast in human plasma using montelukast d6 as internal standard (IS). After solid phase extraction (SPE), the analyte and the IS were chromatographed on a C18 columns using a isocratic mobile phase composed of acetonitrile–5mM ammonium acetate (80:20, v/v) pumped at a flow rate of 0.8mL/min. The proposed method was validated in the range of 5.01–599.91 ng/mL as per the US FDA guidelines. Precision and accuracy results were calculated using five successful calibration curves. Analyte stability in true samples and in plasma samples under different conditions were established and results met the acceptance criteria. The chromatographic run time was set at 3 min, which makes the proposed method is high through put. The method was successfully applied to a pharmacokinetic study in healthy South Indian male subjects under fasting condition.

In this paper the authors proposed a simple, sensitive and selective liquid chromatography–tandem mass spectrometry (LC–MS/MS) assay method for the determination of mosapride in human plasma. This method employed mosapride–d5 as an internal standard (IS). Analyte and the IS were extracted form 100 µL of human plasma using solid–phase extraction with no drying, evaporation and reconstitution steps. The chromatographic separation was achieved on a C18 column by using a mixture of methanol and 5mM ammonium acetate (80:20, v/v) as the mobile phase at a flow rate of 1.0 mL/min. The linearity of the method was established in the concentration range 0.18–60.0 ng/mL with r2 ³ 0.99. The intra–day and inter–day precision (%CV) and accuracy results in five validation batches across five concentration levels were well within the acceptance limits. The validated method was found to be applicable to clinical studies.