A sensitive LC-ESI-MS/MS method for the quantification of low concentrations of buspirone in human plasma

Abstract

A sensitive and specific liquid chromatography–tandem mass spectrometry method was developed and validated for the quantitation of low concentrations of buspirone in human plasma. The analyte and internal standard (buspirone D8) were extracted by solid phase extraction and the chromatographic separation was performed on a reverse phase column with a mobile phase consisting of acetonitrile–5 mM ammonium acetate–trifluoroacetic acid (90 : 10 : 0.001, v/v/v). The retention time of buspirone and internal standard were 0.95 and 0.94 min respectively. The protonated ion of the analyte and internal standard were quantified in the positive ion mode by multiple reaction monitoring (MRM). The mass transitions m/z 386.24 → 122.10 and 394.28 → 122.00 were used to measure the analyte and internal standard respectively. The assay was validated over the concentration range of 10.4–6690.4 pg mL⁻¹, where the quadratic regression (1/x²) was best fitted. The lower limit of quantitation (LLOQ) was 10.4 pg mL⁻¹ with a signal to noise ratio of more than 10 and the relative standard deviation was less than 15%. Buspirone and buspirone D8 were stable in human plasma when stored on a bench top for 6.43 h, in an autosampler (10 °C) for 70.05 h and after three freeze thaw cycles. Acceptable precision and accuracy were obtained for concentrations over the standard calibration curve range. The analytical run time of 3.0 min made this method suitable for the high throughput analysis of a large number of samples in short period of time. The validated method has been successfully applied in the analysis of buspirone levels in more than 500 human plasma samples in a pharmacokinetic study.