Development of a LC-ESI-MS3 method for determination of nitrendipine in human plasma.

A novel and sensitive method utilizing high performance liquid chromatography coupled with electrospray ionization source tandem mass spectrometry (LC-ESI-MS(3)) was developed for the first time in order to analyze nitrendipine in human plasma samples. Human plasma samples were prepared by protein precipitation with acetonitrile and well resolved on a 100 mm reversed-phase column in gradient elution with 0.05% (v/v) formic acid in acetonitrile as the mobile phase. Determination was performed in MS(3) scan mode for nitrendipine and in the multiple reaction monitoring (MRM) mode for nimodipine (internal standard). This method, having a lower limit of quantification (LLOQ) of 0.05 ng/mL when using a 100 μL sample aliquot (5 pg/sample), is acceptable for calibration of the linearity and repeatability and is of better sensitivity than the reported methods (>0.25 ng/mL). The major advantages of the method are that small sample volume (100 μL) is required, simple sample processing technique, high sensitivity and excellent selectivity is guaranteed by the MS(3) detection. The proposed validated method has been successfully applied to a clinical study on nitrendipine.