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.     

Liquid chromatography tandem mass spectrometry assay to determine the pharmacokinetics of aildenafil in human plasma

A simple, sensitive and specific liquid chromatography/tandem mass spectrometry method for the quantitation of aildenafil, a new phosphodiesterase V inhibitor, in human plasma is presented. The analyte and internal standard, sildenafil, were extracted by a one-step liquid-liquid extraction in alkaline conditions and separated on a C(18) column using ammonia:10mM ammonium acetate buffer:methanol (0.1:15:85, v/v/v) as the mobile phase. The detection by an API 4000 triple quadrupole mass spectrometer in multiple-reaction monitoring mode was completed within 2.5 min. The calibration curve exhibited a linear dynamic range of 0.05-100 ng/ml with a 10 pg/ml limit of detection. The intra- and inter-day precisions measured as relative standard deviation were within 8.04% and 5.72%, respectively. This method has been used in a pharmacokinetic study of aildenafil in healthy male volunteers each given an oral administration of one of the three dosages.     

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%.     

Quantification of artemisinin in human plasma using liquid chromatography coupled to tandem mass spectrometry

A liquid chromatographic tandem mass spectroscopy method for the quantification of artemisinin in human heparinised plasma has been developed and validated. The method uses Oasis HLB™ μ-elution solid phase extraction 96-well plates to facilitate a high throughput of 192 samples a day. Artesunate (internal standard) in a plasma–water solution was added to plasma (50 μL) before solid phase extraction. Artemisinin and its internal standard artesunate were analysed by liquid chromatography and MS/MS detection on a Hypersil Gold C18 (100 mm × 2.1 mm, 5 μm) column using a mobile phase containing acetonitrile–ammonium acetate 10 mM pH 3.5 (50:50, v/v) at a flow rate of 0.5 mL/min. The method has been validated according to published FDA guidelines and showed excellent performance. The within-day, between-day and total precisions expressed as R.S.D., were lower than 8% at all tested quality control levels including the upper and lower limit of quantification. The limit of detection was 0.257 ng/mL for artemisinin and the calibration range was 1.03–762 ng/mL using 50 μL plasma. The method was free from matrix effects as demonstrated both graphically and quantitatively.     

Determination of clarithromycin in human plasma by liquid chromatography-electrospray ionization tandem mass spectrometry

A rapid and sensitive method has been developed for the determination of clarithromycin in human plasma with liquid chromatography-tandem mass spectrometry. Clarithromycin and the internal standard, telmisartan were precipitated from the matrix (50 microl) with 200 microl acetonitrile and separated by HPLC using formic acid:10 mM ammonium acetate:methanol (1:99:400, v/v/v) as the mobile phase. The assay based on detection by electrospray positive ionization mass spectrometry in the multiple-reaction monitoring mode was finished within 2.4 min. Linearity was over the concentration range 10-5000 ng/ml with a limit of detection of 0.50 ng/ml. Intra- and inter-day precision measured as relative standard deviation were <3.73% and <9.93%, respectively. The method was applied in a bioequivalence study of two tablet formulations of clarithromycin.     

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.     

Determination of zabofloxacin in rat plasma by liquid chromatography with mass spectrometry and its application to pharmacokinetic study

The objective of the present study was to develop a rapid and sensitive method for the determination of zabofloxacin, a novel, broad-spectrum fluoroquinolone antibiotic, in rat plasma. Rat plasma samples were deproteinized with methanol, and then were injected into an LC-MS system for quantification. Zabofloxacin and enrofloxacin, which served as an internal standard, were analyzed by selected ion monitoring (SIM) at m/z transitions of 402 for zabofloxacin and 360 for the internal standard. The lower limit of quantification (LLOQ) was determined to be 10 ng/mL, with acceptable linearity ranging from 10 to 5000 ng/mL (R>0.999). The validation parameters for zabofloxacin, such as absolute matrix effect (107.7-116.0%), accuracy (92.5-101.1% for intra-day and 90.3-103.8% for inter-day), precision (7.7-10.2% for intra-day and 4.2-8.9% for inter-day), and stability in rat plasma (96.0-101.8%), were found to be acceptable according to the assay validation guidelines of the FDA (2001). Following oral administration of zabofloxacin to rats at a dose of 20mg/kg, the concentration of zabofloxacin in plasma was quantifiable in plasma samples collected up to 8h following zabofloxacin administration. The method described in the present study is applicable to routine pharmacokinetic studies in rats.     

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.     

A liquid chromatography/tandem mass spectrometry assay to quantitate MS-275 in human plasma

A rapid, sensitive and selective method was developed and validated using LC/MS/MS for determination of MS-275 in human plasma. Sample preparation involved a single step liquid-liquid extraction by the addition of 0.2 ml of plasma with 5 ml acetonitrile/n-butyl-chloride. Separation of the compounds of interest, including the internal standard paclitaxel, was achieved on a Waters X-Terra C(18) (50 mm x 2.1mm i.d., 3.5 microm) analytical column using a mobile phase consisting of acetonitrile/ammonium acetate (pH 2.9; 2mM)(60:40, v/v) containing 0.1% formic acid and isocratic flow at 0.15 ml/min for 3 min. The analytes were monitored by tandem-mass spectrometry with electrospray positive ionization. Linear calibration curves were generated over the range of 0.5-100 ng/ml with values for the coefficient of determination of >0.99. The values for both within day and between day precision and accuracy were well within the generally accepted criteria for analytical methods (<15%). This method was subsequently used to measure concentrations of MS-275 in cancer patients receiving an oral weekly dose of 4 mg/m(2).     

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.     

PMEA-Na在beagle犬血浆中的液相色谱/质谱/质谱联用法测定及其药代动力学

目的建立LC/MS/MS法测定犬血浆中PMEA-Na浓度,进行其药代动力学研究.方法血浆样品经甲醇沉淀蛋白后,采用多反应监测法测定其血药浓度.色谱柱为Xterra MS柱,流动相为甲醇水甲酸(25750.5),流速为 0.25 ml·min-1.Beagle犬分3个剂量组经静脉给药,给药剂量分别为 1.0、3.0 和 6.0 mg·kg-1.药代动力学参数通过DAS软件计算获得.结果PMEA-Na线性范围0.02～20 mg·L-1 (r=0.999);最低检测浓度为 20 μg·L-1,方法回收率为 97.1%～107.3%,日内日间变异分别小于 6.5%、10.8%.beagle 犬在 1.0, 3.0 与 6.0 mg·kg-1剂量下单次iv PMEA-Na后,测得其AUC分别为 2.3±0.5, 8.2±1.3 and 18.5±1.3 mg·L-1·h; t1/2 为 3.9±1.8, 8.4±1.5 and 8.9±0.6 h; CL为 0.44±0.09, 0.35±0.05 and 0.31±0.03 ml·h-1·kg-1.结论本方法专属性强,准确性好,可用于PMEA-Na血药浓度测定和药代动力学研究.     

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.     

Liquid chromatography tandem mass spectrometry method for simultaneous determination of antidiabetic drugs metformin and glyburide in human plasma

A simple and rapid liquid chromatography/tandem mass spectrometry (LC-MS/MS) method has been developed and validated for the simultaneous quantitation of antidiabetic drugs metformin and glyburide in human plasma using glimepiride as internal standard (IS). After acidic acetonitrile-induced protein precipitation of the plasma samples, metformin, glyburide and IS were chromatographed on reverse phase C18 (50 mm x 4.6 mm i.d., 5 microm) analytical column. Quantitation was performed on a triple quadrupole mass spectrometer employing electrospray ionization technique and operating in multiple reaction monitoring (MRM) and positive ion mode. The total chromatographic run time was 3.5 min and calibration curves were linear over the concentration range of 20-2500 ng/ml for metformin and 5-500 ng/ml for glyburide. The method was validated for selectivity, sensitivity, recovery, linearity, accuracy and precision, dilution integrity and stability studies. The recoveries obtained for the analytes and IS (>or=69%) were consistent and reproducible. Inter-batch and intra-batch coefficient of variation across four validation runs (LLOQ, LQC, MQC and HQC) was less than 8%. The accuracy determined at these levels was within +/-8% in terms of relative error (RE). The method was applied to a bioequivalence study of 500 mg metformin and 5mg of glyburide tablet after oral administration to 28 healthy human subjects under condition of fasting.     

Analysis of carvedilol in human plasma using hydrophilic interaction liquid chromatography with tandem mass spectrometry

A rapid, sensitive and selective method for the determination of carvedilol in human plasma was developed using hydrophilic interaction liquid chromatography with tandem mass spectrometry (HILIC-MS/MS). Carvedilol and cisapride (internal standard) were extracted from human plasma with methyl tert-butyl ether at basic pH and analyzed on an Atlantis HILIC Silica column with the mobile phase of acetonitrile-ammonium formate (50 mM, pH 4.5) (90:10, v/v). The analytes were detected using an electrospray ionization tandem mass spectrometry in the multiple-reaction-monitoring mode. The standard curve was linear (r=0.9998) over the concentration range of 0.1-200 ng/ml. The lower limit of quantification for carvedilol was 0.1 ng/ml using 50 microl plasma sample. The coefficient of variation and relative error for intra- and inter-assay at four QC levels were 1.6-4.5% and -6.4 to 4.8%, respectively. The absolute and relative matrix effect for carvedilol and cisapride were practically absent. The extraction recoveries of carvedilol and cisapride were 81.6 and 85.2%, respectively. This method was successfully applied to the bioequivalence study of carvedilol in humans.     

Analytical method for determination of allylic isoprenols in rat tissues by liquid chromatography/tandem mass spectrometry following chemical derivatization with 3-nitrophtalic anhydride

A liquid chromatography-tandem mass spectrometric (LC-MS/MS) method following chemical derivatization with 3-nitrophtalic anhydride was developed for the simultaneous determination of farnesol and geranylgeraniol in rat liver and testis. One analogue compound of the analytes, n-pentadecanol, was used as an internal standard (IS) for both analytes in this method. Rat tissues were disintegrated with 8% KOH ethanol solution, and then farnesol, geranylgeraniol and IS were extracted with a mixture of n-hexane-ethanol (98.5:1.5, v/v) in twice. Farnesol, geranylgeraniol and IS were then converted to 3-nitrophtalic derivatives of each analyte, and extracted with n-hexane. A turbo ion spray interface was used as the ionization source of LC-MS/MS and the analysis was performed in the multiple reaction monitoring (MRM) mode. The calibration curve at the spiked concentrations of 0.15-15 microg/g for both analytes showed good linearity. The method was precise; the relative standard deviations of the method for rat liver were not more than 13.4 and 5.4% for farnesol and geranylgeraniol, respectively, and those for rat testis were not more than 8.4 and 8.6% for farnesol and geranylgeraniol, respectively. The accuracies of the method for both rat liver and testis were good, with the deviations between the nominal concentration and calculated concentration of farnesol and geranylgeraniol typically being within 12.3 and 10.2%, respectively. This method provided reliable concentration levels for farnesol and geranylgeraniol in rat liver and testis.     

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.     

Simultaneous determination of alfentanil and midazolam in human plasma using liquid chromatography and tandem mass spectrometry

A fast, sensitive and selective liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the determination of alfentanil and midazolam in human plasma has been developed and validated. Alfentanil and midazolam were extracted from plasma using a mixed-mode cation exchange solid phase extraction method, with recoveries of both compounds greater than 80% at 3 different concentrations (1, 10 and 100ng/ml). Compounds were analyzed on a C(18) column with a water and methanol mobile phase gradient with acetic acid as an additive, at a flow rate of 0.3ml/min. The working assay range was linear from 0.25 to 100ng/ml for each compound. The signal to noise ratio was 80 and 40 for alfentanil and midazolam, respectively, at the lowest concentration calibration standard, with less than 10% matrix suppression by human plasma at this concentration. Alfentanil and midazolam were stable in human plasma during storage at -80°C, processing, and analysis. The procedure was validated and applied to the analysis of plasma samples from healthy human subjects administered oral and intravenous alfentanil and midazolam.     

超高效液相色谱-串联质谱法测定人血浆中安罗替尼浓度的方法学研究及应用

目的：建立一种快速测定人血浆中安罗替尼浓度的超高效液相色谱-串联质谱法(UPLC-MS/MS)并评估临床应用。方法：以泽布替尼为内标物,血浆用乙腈蛋白沉淀,使用Ultimate XB-C18色谱柱 (100mm × 2.1mm, 3.0μm) 分离,流动相为10mM醋酸胺+0.1%甲酸和乙腈进行梯度洗脱,流速为0.6 mL/min,进样量为5μL。应用电喷雾离子化,正离子模式下用多反应模式监测安罗替尼(m/z 408.1→339.1)和内标物(m/z 472.2→290.1)的浓度,考察该方法学的专属性、定量下限与标准曲线、精密度与回收率、基质效应与稳定性及临床应用。结果：安罗替尼在1.0-100.0ng/ml线性关系良好,标准曲线为y=0.515148x+0.0144461(R₂^=0.9984),精密度RSD小于9%,回收率和基质效应分别是104.81-107.32% 和102.54%-104.26%,该方法稳定性良好、血浆基质对安罗替尼测定结果影响较小。本研究考察了52名服用安罗替尼单药治疗的非小细胞肺癌患者,采集服用安罗替尼治疗第43天的谷浓度血浆,并对其血药浓度进行测定,发现所有患者安罗替尼的血药浓度均高于1.0 ng/mL (最低定量下限),血药浓度均值±标准差是11.38± 4.29ng/mL,变异系数是37.66%,表现出较大的个体间差异。结论：本方法灵敏度高、专属性强、定量准确,适用于人血浆中安罗替尼的浓度监测。     

Liquid chromatography tandem mass spectrometry assay for the simultaneous determination of venlafaxine and O-desmethylvenlafaxine in human plasma and its application to a bioequivalence study

A rapid, simple and sensitive liquid chromatography tandem mass spectrometry (LC-MS/MS) assay for simultaneous determination of venlafaxine (VEN) and its active metabolite, O-desmethylvenlafaxine (ODV) in human plasma was developed using nadolol as internal standard (IS). The analytes and IS were extracted from 200 microl aliquots of human plasma via protein precipitation using 0.43% formic acid in acetonitrile and separated on a Hypurity cyano (50 mm x 4.6 mm, 5 microm) column. Quantitation was performed on a triple quadrupole mass spectrometer employing electrospray ionization technique, operating in multiple reaction monitoring (MRM) and positive ion mode. The precursor to product ion transitions monitored for VEN, ODV and IS were m/z 278.3-->58.1, 264.3-->58.1 and 310.4-->254.1, respectively. The total chromatographic runtime was 3 min with retention time for VEN, ODV and IS at 1.93, 1.50 and 1.29 min, respectively. The method was fully validated for its sensitivity, accuracy and precision, linearity, recovery, matrix effect, dilution integrity and stability studies. The linear dynamic range of 2.0-500 ng/ml was established for both VEN and ODV with mean correlation coefficient (r), 0.9994 and 0.9990, respectively. The intra-batch and inter-batch precision (%CV) in three validation batches across five concentration levels (LLOQ, LQC, MQC, HQC and ULOQ) was less than 12.6% for both the analytes. The accuracy determined at these levels was within -9.8 to +3.9% in terms of %bias. The method was successfully applied to a bioequivalence study of 150 mg venlafaxine extended release capsule formulation in 22 healthy Indian male subjects under fed condition.     

Determination of a novel low-voltage-activated calcium channel blocker (HYP-10) in rat plasma by liquid chromatography-mass spectrometry

A novel T-type calcium channel blocker, 4-amino-1-{4-[(4-chloro-phenyl)-phenyl-methyl]-piperazin-1-yl}-butan-1-one (HYP-10) has been synthesized, and the compound has shown promise as both a nociceptive and inflammatory pain reliever as well as an analgesic in a rat neuropathic pain model. A quantification method was developed for the determination of HYP-10 in rat plasma. After simple protein precipitation with methanol, HYP-10 and the internal standard, methaqualone 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 HYP-10 concentration after a single intravenous administration of the compound in rats.