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To better understand different traditional uses of the stems (known as Mahuang) and roots (known as Mahuanggen) of Ephedra sinica, their chemical difference should be investigated. In this study, an ultra-fast liquid chromatography coupled with ion trap time-of-flight mass spectrometry untargeted metabolomics approach was established to reveal global chemical difference between Mahuang and Mahuanggen. Clear separation was observed in scores plots of principal component analysis and orthogonal partial least squares-discriminant analysis. Twenty two chemical markers responsible for such separation were screened out and unambiguously/tentatively characterized. Then chemical markers of pharmacologically important ephedrine and pseudoephedrine were absolutely quantified using liquid chromatography coupled with tandem mass spectrometry under multiple reaction monitoring mode. The results showed that Mahuang was rich in ephedrine-type alkaloids, while Mahuanggen was rich in macrocyclic spermine alkaloids. Additionally, different types of flavan-3-ols and flavones exist in Mahuang and Mahuanggen extracts. This research facilitates a better understanding of different traditional uses of Mahuang and Mahuanggen and provides references for chemical analysis of other medicinal plants. [ABSTRACT FROM AUTHOR]

Da-Cheng-Qi decoction (DCQT) is a traditional purgative Chinese decoction with a history of 2000 years. To study the effect of interactions between the ingredients on the overall chemical composition of DCQT, a chemomic and chemometric approach based on ultra-fast liquid chromatography with ion trap time-of-flight mass spectrometry was developed and validated. After mixing and decocting all four ingredients to make the DCQT, the concentrations of some chemicals are significantly different from those in single herb decoction and 24 of them were identified and tentatively characterized by comparing their data with those of standard compounds or literature data. No new chemicals were formed during mixing and decoction. Our findings indicated that there are interactions between these natural medicines during the mixing and preparation process. The 24 identified chemicals could be used as chemical markers for optimizing prescription and evaluation of consistent quality, and the strategy in the present study could be applied for other multiherb formulae. [ABSTRACT FROM AUTHOR]

Artificial Calculus Bovis is a major substitute in clinical treatment for Niuhuang, a widely used, efficacious but rare traditional Chinese medicine. However, its chemical structures and the physicochemical properties of its components are complicated, which causes difficulty in establishing a set of effective and comprehensive methods for its identification and quality control. In this study, a simple, sensitive and reliable liquid chromatography–tandem mass spectrometry method was successfully developed and validated for the simultaneous determination of bilirubin, taurine and major bile acids (including six unconjugated bile acids, two glycine-conjugated bile acids and three taurine-conjugated bile acids) in artificial Calculus Bovis using a Zorbax SB-C18 column with a gradient elution of methanol and 10 mmol/L ammonium acetate in aqueous solution (adjusted to pH 3.0 with formic acid). The mass spectra were obtained in the negative ion mode using dehydrocholic acid as the internal standard. The content of each analyte in artificial Calculus Bovis was determined by monitoring specific ion pairs in the selected reaction monitoring mode. All analytes demonstrated perfect linearity (r2 > 0.994) in a wide dynamic range, and 10 batches of samples from different sources were further analyzed. This study provided a comprehensive method for the quality control of artificial Calculus Bovis. [ABSTRACT FROM PUBLISHER]

Abstract: The mechanism for the separation of matrine-type alkaloids (sophoridine, sophoramine, sophocarpine, matrine, and oxymatrine) on a C18 column with a mobile phase containing room temperature ionic liquids (RTILs) as additive was studied in the current work by investigating several factors that influenced chromatographic behavior, including mobile phase pH, buffer solution concentration, ionic liquid concentration, and length of alkyl groups in RTILs. Peak efficiency was selected as the criterion for chromatographic efficiency whereas peak efficiency was also selected for triethylamine (TEA). The addition of RTILs in a mobile phase demonstrated superior effects on the separation of these basic compounds because of the increase in peak efficiency. The difference between RTILs and TEA and the changes in retention factors caused by the additives concentration, depending on the acidity of the mobile phase, showed the dual nature of the ionic liquids. This allowed both the constituting anion and cation to participate in the retention mechanism. Furthermore, the chromatographic behaviors of analytes with a mobile phase containing RTILs having different lengths of alkyl groups at different concentrations, complied with the stoichiometric displacement model for retention (SDM-R). This clarified the significant role of competitive adsorption between solutes and additives on the stationary phase. [Copyright &y& Elsevier]

Six impurities in sodium tanshinone IIA sulfonate (STS) were observed by high performance liquid chromatography (HPLC) using DAD detector. One of the impurities, sodium tanshinone I sulfonate was reported in literature, other five impurities were unknown having not been reported previously. Initially, all the six impurities were identified by the liquid chromatography-mass spectrometry (LC-MS) data. After the recrystallization, enrichment and primary separation with silica column of the crude samples of STS, four imputies were isolated from the crude sample by preparative HPLC. Based on the spectral data (UV, MS, 1H NMR and 13C NMR), the structure of these impurities were characterised as, sodium methyl tanshinonate sulfonate (impurity I), sodium tanshinone I sulfonate (impuritiy II), sodium 1,2-dehydro tanshinone IIA sulfonate (impurity III) and sodium przewaquinone A sulfonate (impurity IV). [ABSTRACT FROM AUTHOR]

Abstract: A sensitive and specific liquid chromatography–atmospheric pressure chemical ionisation-mass spectrometry (LC–APCI-MS) method has been developed and validated for the identification and quantification of zaleplon in human plasma using estazolam as an internal standard (IS). After the addition of estazolam and 2.0M sodium hydroxide solution, plasma samples were extracted with ethyl acetate and then the organic layer was evaporated to dryness. The reconstituted solution of the residue was injected onto a prepacked Shim-pack VP-ODS C18 (250mm×2.0mm i.d.) column and chromatographed with a mobile phase comprised of methanol:water (70:30) at a flow-rate of 0.2ml/min. Detection was performed on a single quadrupole mass spectrometer by selected ion monitoring (SIM) mode via atmospheric pressure chemical ionization (APCI) source. The mean standard curve was linear (r =0.9991) over the concentration range of 0.2–100ng/ml and had good back-calculated accuracy and precision. The intra-day and inter-day precisions were within 10% relative standard deviation and accuracy ranged from 85% to 115%. The limit of detection was 0.1ng/ml. The validated LC–APCI-MS method has been used successfully to study zaleplon pharmacokinetic, bioavailability and bioequivalence in 18 adult 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]

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 zolmitriptan in human plasma. After the addition of the internal standard (IS) and 1.0M sodium hydroxide solution, plasma samples were extracted with methylene chloride:ethyl acetate mixture (20:80, v/v). The organic layer was evaporated under a stream of nitrogen at 40°C. The residue was reconstituted with 100μl mobile phase. The compounds were separated on a prepacked Lichrospher CN (5μm, 150mm×2.0mm) column using a mixture of methanol:water (10mM NH4AC, pH 4.0)=78:22 as mobile phase. Detection was performed on a single quadrupole mass spectrometer by selected ion monitoring (SIM) mode via electrospray ionization (ESI) source. The method was proved to be sensitive and specific by testing six different plasma batches. Linearity was established for the range of concentrations 0.30–16.0ng/ml with a coefficient of determination (r) of 0.9998 and good back-calculated accuracy and precision. The intra- and inter-day precision (R.S.D.%) were lower than 15% and accuracy ranged from 85 to 115%. The lower limit of quantification was identifiable and reproducible at 0.30ng/ml. The proposed method enables the unambiguous identification and quantification of zolmitriptan for pharmacokinetic, bioavailability or bioequivalence studies. [Copyright &y& Elsevier]

Abstract: A sensitive and universal LC–MS/MS method for the simultaneous determination of famotidine, cimetidine, ranitidine and lafutidine in human plasma was presented. This is the first single LC–MS/MS method reported for the simultaneous analysis of these four H2 antagonists in human plasma. Following liquid–liquid extraction with ethyl acetate, the separation was performed on an Agilent Zorbax SB-CN (150mm×2.1mm I.D., 5μm) column using a mobile phase consisted of methanol:20mM ammonium acetate (55:45, v/v). The total run time was 7min per sample. Quantification was performed by electrospray ionization–triple quadrupole mass spectrometry by selected reaction monitoring (SRM) detection in the positive mode. All calibration curves showed good linear regression (r 2 >0.99) from 0.5 to 1000ng/mL for famotidine and lafutidine, and 5–20,000ng/mL for cimetidine and ranitidine. The method showed good precision and accuracy with overall intra- and inter-day variations of 1.37–9.29% and 3.51–9.40%, respectively. The assay was successfully applied to a bioequivalence study using ranitidine as the model compound. [Copyright &y& Elsevier]

Abstract: A selective and sensitive high performance liquid chromatography-electrospray ionization-tandem mass spectrometry (ESI-MS/MS) method for simultaneous determination of metformin and rosiglitazone in human plasma using phenformin as internal standard (IS) has been first developed and validated. Plasma samples were precipitated by acetonitrile and the analytes were separated on a prepacked Phenomenex Luna 5u CN 100A (150mm×2.0mm I.D.) column using a mobile phase comprised of methanol:30mM ammonium acetate pH 5.0 (80:20, v/v) delivered at 0.2ml/min. Detection was performed on a Finnigan TSQ triple-quadrupole tandem mass spectrometer in positive ion selected reaction monitoring (SRM) mode using electrospray ionization. The ion transitions monitored were m/z 130.27→71.11 for metformin, m/z 358.14→135.07 for rosiglitazone and m/z 206.20→105.19 for the IS. The standard curves were linear (r 2 >0.99) over the concentration range of 5–3000ng/ml for metformin and 1.5–500ng/ml for rosiglitazone with acceptable accuracy and precision, respectively. The within- and between-batch precisions were less than 15% of the relative standard deviation. The limit of detection (LOD) of both metformin and rosiglitazone was 1ng/ml. The method described is precise and sensitive and has been successfully applied to the study of pharmacokinetics of compound metformin and rosiglitazone capsules in 12 healthy Chinese volunteers. [Copyright &y& Elsevier]

Abstract: A selective and sensitive high performance liquid chromatography–electrospray ionisation–mass spectrometry method has been developed for the determination of balofloxacin (BLFX) in human plasma. The sample preparation was a liquid–liquid extraction, and chromatographic separation was achieved with an Agilent ZORBAX 300SB C18 2.1mm×150mm column using a mobile phase comprised of methanol–water (10mM CH3COONH4, pH 3.0)=40:60 (v/v). Standard curves were linear (r =0.9992) over the concentration range of 0.03–3μg/ml and had good accuracy and precision. The within- and between-batch precisions were within 10% relative standard deviation (R.S.D.). The limit of detection (LOD) was 0.02μg/ml. The validated HPLC–electrospray ionization (ESI)–MS method has been used successfully to study balofloxacin pharmacokinetics in healthy volunteers. [Copyright &y& Elsevier]

Abstract: A rapid and sensitive method based on liquid chromatography–tandem mass spectrometry (LC–MS/MS) for the simultaneous determination of codeine, ephedrine, guaiphenesin and chlorpheniramine in beagle dog plasma has been developed and validated. Following liquid–liquid extraction, the analytes were separated on a reversed-phase C18 column (150mm×2.0mm, 3μm) using formic acid:10mM ammonium acetate:methanol (0.2:62:38, v/v/v) as mobile phase at a flow rate of 0.2mL/min and analyzed by a triple-quadrupole mass spectrometer in the selected reaction monitoring (SRM) mode. The method was linear for all analytes over the following concentration (ng/mL) ranges: codeine 0.08–16; ephedrine 0.8–160; guaiphenesin 80–16,000; chlorpheniramine 0.2–40. Acceptable precision and accuracy were obtained for concentrations over the standard curve range. It is the first time that the validated HPLC–MS/MS method was successfully applied to a bioequivalence study in 6 healthy beagle dogs. [Copyright &y& Elsevier]

Abstract: A simple, rapid, sensitive and selective liquid chromatographic–tandem mass spectrometric (LC–MS/MS) method was developed and validated for the quantification of rupatadine in human plasma using estazolam as internal standard (IS). Following liquid–liquid extraction, the analytes were separated using a mobile phase of methanol–ammonium acetate (pH 2.2; 5mM) (50:50, v/v) on a reverse phase C18 column and analyzed by a triple-quadrupole mass spectrometer in the positive ion and multiple reaction monitoring (MRM) mode, m/z 416→309 for rupatadine and m/z 295→267 for the IS. The assay exhibited a linear dynamic range of 0.1–100ng/ml for rupatadine in human plasma. The lower limit of quantification (LLOQ) was 0.1ng/ml with a relative standard deviation of less than 20%. 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 rupatadine in healthy volunteers. [Copyright &y& Elsevier]