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A liquid chromatography-tandem mass spectrometry was developed and validated for the simultaneous determination of protocatechuic aldehyde, danshensu, salvianolic acid B, and hydroxysafflor yellow A, with rutin as internal standard. Electrospray ionization patterns and efficiency of the analytes, along with their fragmentation, were investigated to achieve sensitive electrospray tandem mass spectrometry (ESI-MS/MS) detection. Plasma samples were extracted by solid-phase extraction columns, and the analytes were separated on a Dikma Diamonsil C18 (200 mm×4.6 mm i.d., 5 µm) column using a mobile phase comprised of methanol:acetonitrile: 0.5% formic acid (20:25:55, v/v/v) at a flow rate of 1 ml/min. Detection was performed on a Finnigan TSQ ripple quadrupole tandem mass spectrometer in negative ion-selected monitoring mode using electrospray ionization. Good linearity over the range 10-1000 ng/ml for danshensu, salvianolic acid B, and hydroxysafflor yellow A, and 5-500 ng/ml for protocatechuic aldehyde with acceptable accuracy and precision, respectively. All the validation data, such as accuracy, precision, and stability, were within the required limits. It was a potential platform for the pharmacokinetic and absorption, distribution, metabolism, and excretion (ADME) study of multiple constituent traditional Chinese medicine. [ABSTRACT FROM AUTHOR]

Abstract: A rapid, sensitive and selective LC–MS/MS method was developed and validated for the quantification of aniracetam in human plasma using estazolam as internal standard (IS). Following liquid–liquid extraction, the analytes were separated using a mobile phase of methanol–water (60:40, v/v) on a reverse phase C18 column and analyzed by a triple-quadrupole mass spectrometer in the selected reaction monitoring (SRM) mode using the respective [M+H]+ ions, m/z 220→135 for aniracetam and m/z 295→205 for the IS. The assay exhibited a linear dynamic range of 0.2–100ng/mL for aniracetam in human plasma. The lower limit of quantification (LLOQ) was 0.2ng/mL with a relative standard deviation of less than 15%. Acceptable precision and accuracy were obtained for concentrations over the standard curve range. The validated LC–MS/MS method has been successfully applied to study the pharmacokinetics of aniracetam in healthy male Chinese volunteers. [Copyright &y& Elsevier]

Abstract: A sensitive and specific liquid chromatography electrospray ionization mass spectrometry (LC–ESI–MS) method has been developed and validated for the identification and quantification of tulobuterol in rabbits’ plasma. After the addition of clenbuterol-HCl, the internal standard (IS) and 1.0M sodium hydroxide solution, plasma samples were extracted using a solvent mixture comprised of 5% isopropanol in n-hexane. The compounds were separated on a prepacked Lichrospher CN (5μm, 150mm×2.0mm) column using a mixture of methanol–water (10mM CH3COONH4, pH 4.0) as mobile phase. A Shimadzu LCMS-2010A mass spectrometer connected to a Shimadzu high performance liquid chromatograph (HPLC) was used to develop and validate the method. The method has shown to be sensitive and specific by testing six different blank plasma batches. Linearity was established for the range of concentrations 0.50–40.0ng/mL with a coefficient of determination (r) of 0.9998. The intra-day precision was better than 15%. The lower limit of quantification (LLOQ) was identifiable and reproducible at 0.50ng/mL. The proposed method enables the unambiguous identification and quantification of tulobuterol for pharmacokinetic, bioavailability or bioequivalence studies. [Copyright &y& Elsevier]