Quantitative assay for bradykinin in rat plasma by liquid chromatography coupled to tandem mass spectrometry

An assay to quantify bradykinin in rat plasma has been developed and validated, using liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). Sar-D-Phe(8)-des-Arg(9)-bradykinin was used as internal standard. Aprotinin was added to rat plasma to inhibit the activity of proteinases. Recoveries for solid-phase extraction (SPE) on Strata X reversed phase were greater than 80%. Multiple reaction monitoring (MRM) on a triple quadrupole mass spectrometer equipped with an electrospray source (ESI), operating in the positive ion-mode, was used for detection. The assay was validated and stability was explored. Bradykinin (10-500 ng/mL) was quantified with accuracy values (% RE) below 10% and intra- and inter-day precisions (% RSD) below 12 and 16%, respectively, for all concentrations. The method was successfully applied to several plasma samples from low levels kallikrein rats (LKRs) compared with normal kallikrein rats (NKRs).     

Liquid chromatography-tandem mass spectrometry for the determination of jaceosidin in rat plasma

Jaceosidin (4′,5,7-trihydroxy–3′,6-dimethoxyflavone), isolated from Artemisia species as well as Eupatorium species, has antiallergic, anticancer, anti-inflammatory and antioxidant activity. A rapid, sensitive and selective liquid chromatography-tandem mass spectrometric (LC/MS/MS) method for the quantification of jaceosidin in rat plasma was developed to characterize the pharmacokinetics of jaceosidin. Jaceosidin and the internal standard, linezolid, were extracted from rat plasma with ethyl acetate at acidic pH and analyzed on a Luna phenyl-hexyl column using the mixture of acetonitrile and 0.1% formic acid (45:55, v/v) as a mobile phase. The analytes were determined using an electrospray ionization tandem mass spectrometry in the multiple-reaction-monitoring mode. The calibration curve was linear (r² = 0.9973) over the concentration range of 2.00–500 ng/ml. The lower limit of quantification for jaceosidin was 2.0 ng/ml using 50 μl of plasma sample. The coefficients of variation of intra- and inter-assay at four QC levels were 2.4–9.6% and the relative errors were −9.1 to 10.0%. The matrix effects for jaceosidin and linezolid were practically absent. The recoveries of jaceosidin and linezolid were 87.0 and 87.7%, respectively. This method was successfully applied to the pharmacokinetic study of jaceosidin in rats.     

Quantitative determination of spinosin in rat plasma by liquid chromatography-tandem mass spectrometry method

A sensitive method for the quantitative determination of spinosin in rat plasma was developed and validated using high-performance liquid chromatographic separation with tandem mass spectrometric detection. The analytes of interest were extracted from rat plasma samples by methyl tert-butyl ether (MTBE) after acidification with 1.0% acetic acid aqueous solution. Chromatographic separation was achieved on an Agilent Zorbax SB-C(18) (50 mm x 4.6 mm, 5 microm) using a isocratic mobile phase consisting of acetonitrile-water (30:70, v/v) with 1% isopropyl alcohol and 0.01% heptafluorobutyric acid. The flow rate was 0.2 ml/min. The column temperature was maintained at 25 degrees C. Detection was performed on a triple quadrupole tandem mass spectrometer by selected reaction monitoring (SRM) mode via electrospray ionization (ESI). The calibration curve was linear over the range of 1.00-400 ng/ml in rat plasma, with 1.00 ng/ml of the lower limit of quantification (LLOQ). The inter- and intra-day precisions and accuracy for all samples were satisfactory. The validated method was successfully applied for the pharmacokinetic study of spinosin in rat. After oral administration of 20mg/kg spinosin to rats, the main pharmacokinetic parameters of T(max), C(max), T(0.5) and AUC(0-T) were 5.33+/-0.58 h, 132.2+/-10.6 ng/ml, 4.89+/-0.37 h, 1.02+/-0.09 microg h/l, respectively.     

在线SPE HPLC-DAD方法测定大鼠血浆环磷酰胺浓度(英文)

建立快速简便的在线固相萃取液相(on-line SPE HPLC-DAD)分析方法,测定大鼠血浆中环磷酰胺的浓度。该方法为:将Acclaim Polar Advantage II C18保护柱(PA II柱,10mm×4.6mm,5μm)作为在线SPE柱,去蛋白的血浆样品进样后,100%H2O洗脱1min;经PA II C18柱(150mm×4.6mm,5μm)分析,流动相为乙腈水(40:60,v/v),流速为1mL/min,检测波长为195nm。经过验证发现该方法的选择性好,线性、精密度、准确度和灵敏度高,可用于临床监测环磷酰胺浓度。     

A rapid and sensitive liquid chromatography–tandem mass spectrometric method for the determination of timosaponin B-II in blood plasma and a study of the pharmacokinetics of saponin in the rat

A rapid, sensitive and selective liquid chromatography–tandem mass spectrometric (LC–MS/MS) method was developed and validated for the determination of Timosaponin B-II (TB-II), a pharmacologically active constituent isolated from Anemarrhena asphodeloides. This method was used to examine the pharmacokinetics and bioavailability of TB-II in rats using ginsenoside Re as an internal standard. After simple protein precipitation of the plasma samples with acetonitrile, the analytes were separated on an ODS column (150 mm × 2.1 mm i.d., 5 μm) with the mobile phase of acetonitrile–water (35:65, v/v) containing 0.05% formic acid and detected by electrospray ionization mass spectrometry in the negative multiple reaction monitoring (MRM) mode with a chromatographic run time of 3.0 min. The calibration curves were linear over the range of 5–15,000 ng/ml and the lower limit of quantification (LLOQ) was 5 ng/ml in rat plasma. In this range, relative standard deviations (R.S.D.) were <7.4% for intra-day precision and <9.0% for inter-day precision. The accuracy was within the range of 97.7–107.3%. The method was successfully applied to assess the pharmacokinetics and oral bioavailability of TB-II after intravenous and oral administration in rats, with the oral bioavailability being only 1.1%.     

Liquid chromatography-electrospray lonization tandem mass spectrometric determination of lornoxicam in human plasma

A rapid, sensitive and selective liquid chromatography-electrospray ionization tandem mass spectrometric (LC-ESI-MS/MS) method for the determination of lornoxicam in human plasma was developed. Lornoxicam and isoxicam (internal standard) were extracted from human plasma with ethyl acetate at acidic pH and analyzed on a Sunfire C18 column with the mobile phase of methanol:ammonium formate (10 mM, pH 3.0) (70:30, v/v). The analyte was detected using a mass spectrometer, equipped with electrospray ion source. The instrument was set in the multiple-reaction-monitoring mode. The standard curve was linear (r = 0.9998) over the concentration range of 0.50-500 ng/mL. The coefficient of variation and relative error for intra- and inter-assay at four QC levels were 0.7 to 4.2% and -4.5 to 5.0%, respectively. The recoveries of lornoxicam and isoxicam were 87.8% and 66.5%, respectively. The lower limit of quantification for lornoxicam was 0.50 ng/mL using a 200 pL plasma sample. This method was successfully applied to a pharmacokinetic study of lornoxicam after oral administration of lornoxicam (8 mg) to humans.     

Identification of multiple constituents in the traditional Chinese medicine formula Sheng-Mai San and rat plasma after oral administration by HPLC-DAD-MS/MS

Sheng-Mai San (SMS), a traditional Chinese medicine formula, has been used for the treatment of cardiovascular disease in Asia over long period of time. While its effectiveness has been confirmed by clinical use, its active chemical constituents remain unclear. In this paper, an HPLC-DAD-MS/MS method is described for the efficient and rapid identification of the chemical constituents in SMS extract. MS/MS fragmentation behavior of authentic compounds was proposed for aiding the structural identification of the components. A total of 53 compounds were identified or tentatively characterized by comparing their retention times, UV and MS spectra with those of authentic compounds or literature data. HPLC/UV and MS techniques were employed to screen for the potential bioactive components in rat plasma after oral administration of SMS. Twenty-five compounds including 14 prototype components and 11 metabolites were detected in dosed rat plasma compared with blank rat plasma. This identification and structural elucidation of the chemical constituents in the medicine formula and rat plasma may provide important experimental data for further pharmacological and clinical research.     

Liquid chromatography/tandem mass spectrometry for the determination of changrolin in rat plasma: Application to a bioavailability study

A sensitive and specific LC–CMS/MS method was developed for the quantification of changrolin, an anti-arrhythmic drug, in rat plasma using tiapride as internal standard. Liquid–liquid extraction was employed for sample preparation and analyzed using a multiple reaction monitoring mode with electrospray positive ionization source. The calibration curve for changrolin was linear over the range 5–1600 ng/mL with coefficients of correlation >0.99. The intra- and inter-batch precision was less than 8.6%, and accuracy ranged from 94.6% to 104.5%. This validated LC–MS/MS method was successfully applied to a bioavailability study of oral and intravenous administration of changrolin with 20 mg/kg dosage in SD rats.     

Quantitative determination of daumone in rat plasma by liquid chromatography-mass spectrometry

Daumone, 6-(3,5-dihydroxy-6-methyl-tetrahydro-pyran-2-yloxy)-heptanoic acid is a pheromone secreted by Caenorhabditis elegans, and has been known as a pivotal regulator of chemosensory processes in development and ageing. A quantification method using mass spectrometry was developed for the determination of daumone in rat plasma. After simple protein precipitation with acetonitrile including an internal standard, the analytes were chromatographed on a reversed-phase column and detected by liquid chromatography/tandem mass spectrometry with electrospray ionization. The accuracy and precision of the assay were in accordance with FDA regulations for validation of bioanalytical methods. This method was applied to measure the plasma daumone concentrations after a single intravenous administration of daumone in rats.     

Liquid chromatography-tandem mass spectrometry assay for the quantitation of plagiochin E and its main metabolite plagiochin E glucuronides in rat plasma

Plagiochin E, a macrocyclic bisbibenzyl isolated from liverwort Marchantia polymorpha, was found to have antifungal activity. To evaluate the pharmacokinetics of plagiochin E in rats, a sensitive and specific liquid chromatography/tandem mass spectrometric (LC-MS/MS) method was developed and validated for the quantitation of plagiochin E and its total conjugated metabolites in rat plasma. For detection, a Sciex API 4000 LC-MS/MS with a TurboIonSpray ionization (ESI) inlet in the negative ion-multiple reaction monitoring (MRM) mode was used. The plasma samples were pretreated by a simple liquid-liquid extraction with ethyl acetate. The concentration of plagiochin E parent form was determined directly and the concentration of plagiochin E conjugated metabolites was assayed in the form of plagiochin E after treatment with beta-glucuronidase/sulfatase. The statistical evaluation for this method reveals excellent linearity, accuracy and precision for the range of concentrations 0.5-1000.0 ng/mL. The method had a lower limit of quantification (LLOQ) of 0.5 ng/mL for plagiochin E in 50 microL of plasma. The method was successfully applied to the characterization of the pharmacokinetic profile of plagiochin E in rats after an oral and an intravenous administration.     

Determination of limonin in rat plasma by liquid chromatography-electrospray mass spectrometry

A simple, sensitive and selective liquid chromatography coupled with electrospray ionization mass spectrometry (LC/ESI/MS) method for determination of limonin (LM) in rat plasma has been developed and validated. The method had advantages of a single liquid–liquid extraction with ether and high sensitivity. Analyses were conducted at a flow rate of 0.2 ml/min by a gradient elution. The detection utilized selected ion monitoring in the negative ion mode at m/z 460.00 and 423.15 for the deprotonated molecular ions of LM and the internal standard, respectively. The quantitation limit for LM in rat plasma was 1.0 ng/ml. The linearity was also excellent over the concentration range of 1.9–500 ng/ml of LM. The intra- and inter-day precision (relative standard deviation (R.S.D.%)) was lower than 10% and accuracy ranged from 90 to 110%, showing a good reproducibility. This developed method was successfully applied to analysis of LM in biological fluids.     

An HPLC-MS/MS method for the quantitative determination of 4-hydroxy-anethole trithione in human plasma and its application to a pharmacokinetic study

A selective, rapid and sensitive method for the quantitation of 4-hydroxy-anethole trithione (ATX) in human plasma based on high-performance liquid chromatography–tandem mass spectrometry (HPLC–MS/MS) was developed and validated. Paracetamol was used as the internal standard (I.S.). After liquid–liquid extraction of 500 μL plasma with ethyl acetate, ATX and the I.S. were chromatographed on an Inertsil^® ODS-3 column. The mobile phase was consisted of methanol–water (75:25, v/v) with a flow rate of 0.25 mL/min. The detection was performed on a triple quadrupole tandem mass spectrometer by multiple reaction monitoring (MRM) mode via electrospray ionization (ESI) source. The calibration curve was linear over the range of 0.452–603 ng/mL (r² ≥ 0.99) with a lower limit of quantitation (LLOQ) of 0.452 ng/mL. The intra- and inter-day precision (relative standard deviation, R.S.D.) values were below 13% and the accuracy (relative error, R.E.) was from −2.7% to −7.5% at three quality control levels. The assay herein described was successfully applied to a pharmacokinetic study of anethole trithione (ATT) tablet in healthy volunteers after oral administration.     

采用正负离子切换模式的LC-ESI-MS/MS法测定大鼠灌胃给药后京尼平苷的血浆浓度(英文)

建立了一种快速、专属性强的液相色谱-串联质谱方法(LC-MS/MS)测定中药栀子的主要活性成分–京尼平苷的大鼠血药浓度去评价其临床前药动学特征。京尼平苷血浆样品经沉淀蛋白后,采用DiamonsilC18色谱柱进行分析,采用流动相10mM醋酸铵–甲醇(20:80,v/v),流速0.6mL/min。样品测定采用"Truncated"多反应检测模式,采用正离子m/z411→411测定京尼平苷,采用负离子m/z415→295测定内标葛根素。线性浓度范围为10.0–5000ng/mL,最低定量下限为10.0ng/mL,样品提取回收率范围为84.8%–90.5%。该确证方法成功应用于大鼠灌胃(给药剂量200mg/kg)给予京尼平苷后的药动学研究。     

Fast liquid chromatographic-tandem mass spectrometric (LC-MS-MS) determination of metformin in plasma samples

Liquid chromatographic–tandem mass spectrometric (LC–MS–MS) methods for the determination of metformin in plasma from different species are presented. The first method employed a YMC cyano 2 mm×50 mm, 3 μm analytical column. For minimum sample preparation direct injection of samples after protein precipitation was performed. The polar column used with highly organic mobile phases provided a normal phase retention mechanism. The elution conditions were optimized to obtain reproducible peak areas and good peak shape. A step gradient from 100% acetonitrile to acetonitrile–water 80:20 (v/v) containing 10 mM ammonium acetate and 1% acetic acid was applied, leading to a sample-to-sample cycle time of 2 min. In a second method, a column-switching LC–MS–MS assay for on-line trapping was developed. The analyte and internal standard were trapped on a YMC cyano 2 mm×10 mm, 5 μm column using acetonitrile–methanol 95:5 (v/v). Elution was performed isocratically in back-flush mode on to the analytical column (YMC cyano 2 mm×50 mm, 3 μm) using 10 mM ammonium acetate in acetonitrile–water 80:20 (v/v) with 1% formic acid. With this approach, the signal-to-noise ratio was improved and the run time could be shortened to 1 min. Calibration samples were prepared in the matrix to be assayed in the range of 10–10,000 ng/ml. Quality control (QC) samples were prepared at 40, 400 and 4000 ng/ml and interspersed with the unknown study samples in the assays. Deviations for precision and accuracy were less than 20% for the lower limit of quantification (LLOQ) and low QC sample and less than 15% for other calibrators and QCs.     

Sensitive determination of a pharmaceutical compound and its metabolites in human plasma by ultra-high performance liquid chromatography-tandem mass spectrometry with on-line solid-phase extraction

This paper describes the determination of a drug candidate and two metabolites in human plasma by column-switching LC-MS/MS after protein precipitation. Starting from a standard method with a quantitation limit of 0.5 ng/mL, a highly sensitive assay was developed, employing UHPLC separation and detection on an API 5000 mass spectrometer. The injected plasma equivalent was increased from 6 to 20 μL; conventional column trapping for compound enrichment and removal of matrix constituents was combined with high-pressure analytical separation using small particle columns to improve resolution and signal-to-noise ratio. Quantitation limits were thus lowered to between 5 and 20 pg/mL, offering the possibility to provide bioanalytical support for microdosing studies in humans. Excellent assay quality and robustness were achieved by both methods.     

Determination of chamaechromone in rat plasma by liquid chromatography-tandem mass spectrometry: application to pharmacokinetic study

A rapid, simple and accurate method was developed for the determination of chamaechromone in rat plasma using liquid chromatography tandem mass spectrometry (LC–MS–MS). Rosuvastatin was used as the internal standard. The plasma samples were extracted by liquid–liquid extraction with ethyl acetate. Chromatographic separation was performed on Xbridge™ C₁₈ column (2.1 mm × 50 mm, 3.5 μm) with linear gradient elution using water and methanol, both of which were acidified with 0.1% aqueous formic acid. The flow rate was 0.4 mL/min and the total run time was 6 min. Detection was performed on a triple-quadrupole tandem mass spectrometer using positive ion mode electrospray ionization (ESI) in the multiple reaction monitoring (MRM) mode. The MS/MS ion transitions monitored were m/z 543.3 → 198.9 and 481.9 → 258.3 for chamaechromone and rosuvastatin, respectively. Good linearity was observed over the concentration range of 8–6400 ng/mL in 0.1 mL of rat plasma. The lowest concentration (8 ng/mL) in the calibration curve was estimated as LLOQ with both deviation of accuracy and RSD of precision <20% (n = 6). Intra-assay and inter-assay variability were less than 11% in plasma. This method was successfully applied to a pharmacokinetic study of chamaechromone in rats after intravenous (5 mg/kg) and oral (100 mg/kg) administration. Following oral administration the concentration–time curve of chamaechromone exhibited a biphasic absorption profile. The maximum mean concentration in plasma (C_max, 795.9 ± 14.6 ng/L) was achieved at 11.3 ± 0.8 h (T_max) and the area under curve (AUC_0–60) was 6976.7 ± 1026.9 ng h/L. After single intravenously administration of chamaechromone, the essential pharmacokinetic parameters C_max, AUC_0–48 were 4300.7 ± 113.6 ng/L and 3672.1 ± 225.4 ng h/L, respectively. The result showed that the compound was poorly absorbed with an absolute bioavailability being approximately 8.9%.     

Sensitive and selective liquid chromatography-mass spectrometry method for the quantification of rosiglitazone in human plasma

A sensitive and selective high-performance liquid chromatography-electrospray ionisation-tandem mass spectrometry (HPLC-ESI-MS-MS) method for determination of rosiglitazone in human plasma has been developed. After the addition of the internal standard, plasma samples were precipitated by acetonitrile. The compounds were separated on a proC18 column using a mixture of ammonium acetate buffer (0.02 M, pH 6.5) and acetonitrile (in the ratio of 47:53, v/v) as mobile phase. A Finnigan LCQdeca plus ion trap mass spectrometer connected to a Finnigan Surveyor HPLC was used to develop and validate the method. Linearity was established for the range of concentrations 1-1000 ng/ml with a coefficient of determination (r(2)) of 0.999. The intra-day accuracy for rosiglitazone ranged from 110.0 to 99.2% at low, medium and high levels. The inter-day accuracy was less than 15%. The lower limit of quantitation (LLOQ) was identified reproducible at 1.0 ng/ml with a precision of 5.7%. After validation, the method was used to study the pharmacokinetic profile of rosiglitazone in five healthy volunteers after administration of a single oral dose (4.0mg). The proposed method enabled the unambiguous evaluation and quantitation of rosiglitazone for pharmacokinetic, bioavailability or drug-drug interaction studies. A possible chromatography peak (m/z 121, its parent ion m/z 344) of N-demethyl rosiglitazone was observed at 3.49 min during determining rosiglitazone. This may be also a potential method for simultaneous determination of rosiglitazone and its metabolite N-demethyl rosiglitazone concentrations in plasma.     

Development and full validation of a sensitive quantitative assay for the determination of clemastine in human plasma by liquid chromatography-tandem mass spectrometry

A sensitive high-performance liquid chromatography-tandem mass spectrometry (LC/MS/MS) method was developed and validated for the determination of clemastine in human plasma. After having been extracted from plasma samples by ethyl acetate, clemastine and internal standard, diphenhydramine, were separated on a C(18) column. Detection was performed on Thermo Finnigan TSQ Quantum triple quadrupole mass spectrometer by selected reaction monitoring (SRM) mode via electrospray ionization (ESI) source. The method was linear in the concentration range of 5.0-1000.0 pg/ml for clemastine. The intra- and inter-day precisions were within 13.4% and the deviations were between -1.1% and 5.6%. The fully validated LC/ESI-MS/MS method has been successfully applied to the preliminary pharmacokinetic study in healthy male Chinese volunteers.     

高效液相色谱法测定大鼠血浆中的西他列汀浓度及其药动学研究(英文)

本研究建立并验证了测定大鼠血浆中磷酸西他列汀浓度的高效液相色谱法,并在大鼠体内进行药动学研究。血浆中的药物和内标(氢化可的松)由乙酸乙酯萃取。所用色谱柱为Agilent Zorbax Extend-C18柱(250mm×4.6mm,4μm),进样量为20μL,检测波长为267nm,柱温为30oC。流动相为甲醇–水(60:40,内含10mMTris和10mM三乙胺,并用1M盐酸调至pH9.0)。流速为1.0mL/min。色谱峰具有良好的特异性。在0.75–100.0μg/mL范围内具有良好的线性关系(r>0.9957)。定量下限为0.75μg/mL。日间,日内精密度均小于10%。在0.75,10.0,100.0μg/mL的相对回收率为105.3%,99.8%,99.0%,提取回收率分别为81.5%,82.4%,84.5%。样品的稳定性良好。运用该方法测定了大鼠口服磷酸西他列汀水溶液后的血药浓度,说明本方法可用于药物动力学的研究。     

HPLC测定大鼠血浆中的山奈酚

目的建立测定大鼠血浆中山奈酚的方法。方法以黄芩素为内标,无水乙醚为萃取溶剂,采用HPLC法,Shimm-pack VP-ODS柱为分析柱,乙腈-0.5%冰醋酸(33.3:66.7)为流动相,流速为1.0 ml.min-1,检测波长为370 nm,柱温为40℃。结果山奈酚0.050~5.301μg.ml-1与峰面积比(山奈酚/内标)的线性关系良好,最低定量限为0.020μg.ml-1,4种浓度的平均回收率为96.48%~108.33%,日内RSD≤7.39%,日间RSD≤5.88%,3种浓度的平均萃取回收率为93.67%、98.37%、101.83%。结论所建方法简单、灵敏、准确可靠,可用于山奈酚的药物动力学研究。