Simple method for the determination of rosiglitazone in human plasma using a commercially available internal standard

To the best of our knowledge, bioanalytical methods to determine rosiglitazone in human plasma reported in literature use internal standards that are not commercially available. Our purpose was to develop a simple method for the determination of rosiglitazone in plasma employing a commercially available internal standard (IS). After the addition of celecoxib (IS), plasma (0.25 mL) samples were extracted into ethyl acetate. The residue after evaporation of the organic layer was dissolved in 750 microL of mobile phase and 50 microL was injected on to HPLC. The separation was achieved using a Hichrom KR 100, 250 x 4.6 mm C(18) with a mobile phase composition potassium dihydrogen phosphate buffer (0.01 m, pH 6.5):acetonitrile:methanol (40:50:10, v/v/v). The flow-rate of the mobile phase was set at 1 mL/min. The column eluate was monitored by fluorescence detector set at an excitation wavelength of 247 nm and emission wavelength of 367 nm. Linear relationships (r(2) > 0.99) were observed between the peak area ratio rosiglitazone to IS vs rosiglitazone concentrations across the concentration range 5-1000 ng/mL. The intra-run precision (%RSD) and accuracy (%Dev) in the measurement of rosiglitazone were <+/-10.69 and <-12.35%, respectively across the QC levels (50-1000 ng/mL). The extraction efficiency was >80% for both rosiglitazone and IS from human plasma. The lower limit of quantitation of the assay was 5 ng/mL. In summary, the methodology for rosiglitazone measurement in plasma was simple, sensitive and employed a commercially available IS.     

HPLC analysis and pharmacokinetic study of quercitrin and isoquercitrin in rat plasma after administration of Hypericum japonicum thunb. extract

A simple HPLC method was developed for determination of quercitrin and isoquercitrin in rat plasma. Reversed-phase HPLC was employed for the quantitative analysis using kaempferol-3-O-beta-D-glucopyranoside-7-O-alpha-L-rhamnoside as an internal standard. Following extraction from the plasma samples with ethyl acetate-isopropanol (95:5, v/v), these two compounds were successfully separated on a Luna C(18) column (250 x 4.6 mm, 5 microm) with isocratic elution of acetonitrile-0.5% aqueous acetic acid (17:83, v/v) as the mobile phase. The flow-rate was set at 1 mL/min and the eluent was detected at 350 nm for both quercitrin and isoquercitrin. The method was linear over the studied ranges of 50-6000 and 50-5000 ng/mL for quercitrin and isoquercitrin, respectively. The intra- and inter-day precisions of the analysis were better than 13.1 and 13.2%, respectively. The lower limits of quantitation for quercitrin and isoquercitrin in plasma were both of 50 ng/mL. The mean extraction recoveries were 73 and 61% for quercitrin and isoquercitrin, respectively. The validated method was successfully applied to pharmacokinetic studies of the two analytes in rat plasma after the oral administration of Hypericum japonicum thunb. ethanol extract.     

High-performance liquid chromatographic determination of doxazosin in human plasma for bioequivalence study of controlled release doxazosin tablets

A highly sensitive high-performance liquid chromatographic quantification method with fluorescence detection was developed and validated for the determination of doxazosin in human plasma. The developed method employed one-step extraction of doxazosin from plasma matrix with ethyl acetate using propranolol as an internal standard. Chromatographic separation was obtained within 8.0 min using a reverse-phase Capcell-Pak C(18) column (150 x 4.6 mm i.d., 5 microm) and the mobile phase consisted of methanol-water containing 10 mM perchloric acid and 1.8 mM sodium heptane sulfonic acid (50:50, v/v) and was set at a flow rate of 1.5 mL/min. The calibration curve constructed was linear in the range of 0.3-50.0 ng/mL. The proposed method achieved a lower limit of quantification of 0.3 ng/mL, better than the reported HPLC methods. Average recoveries of doxazosin and the internal standard from human plasma matrix were 87.0 and 85.9%, respectively. The present method was validated by evaluating the precision and accuracy for inter- and intraday variation in the concentration range 0.3-50 ng/mL. The precision values expressed as relative standard deviations in the inter- and intraday validation were 1.17-6.29 and 0.84-5.94%, respectively. This method was successfully applied to the bioequivalence study of two doxazosin controlled release tablets in healthy, male human subjects.     

Simultaneous determination of morniflumate and its major active metabolite,niflumic acid,in human plasma by high‐performance liquid chromatography in stability and pharmacokinetic studies

A rapid, sensitive and stable high‐performance liquid chromatography (HPLC) method was developed and validated for the simultaneous determination of morniflumate and its major active metabolite, niflumic acid, in human plasma. HPLC analysis was carried out using a 5 µm particle size, C₁₈‐bonded silica column with a mixture of acetonitrile and 0.005 m potassium phosphate monobasic in water (60:40, v/v) as the mobile phase and UV detection at 287 nm. The method involved the treatment with 50 μL of 0.4 m hydrochloric acid for the stability of morniflumate, extraction with diethylether and evaporation to dryness under a nitrogen stream. The lower limit of quantitation for morniflumate and niflumic acid was 50 and 500 ng/mL, respectively. The calibration curves for morniflumate and niflumic acid were linear over the concentration range of 50–20,000 ng/mL and 500–50,000 ng/mL, respectively, with correlation coefficients greater than 0.9995 and inter‐ or intra‐batch coefficients of variation not exceeding 13.79%. The variability (percentage difference) of incurred sample re‐analysis did not exceed 11.72% and all of the repeat samples fell within 20% of the mean value. This assay procedure was applied successfully to an examination of the pharmacokinetics of morniflumate and its metabolite, niflumic acid, in human subjects. Copyright © 2013 John Wiley & Sons, Ltd.     

Selective and sensitive determination of bis(7)-tacrine, a high erythrocyte binding acetylcholinesterase inhibitor, in rat plasma by high-performance liquid chromatography-tandem mass spectrometry

The current study aims to develop a specific and sensitive LC-MS/MS method for determination of bis(7)-tacrine (B7T) in rat plasma. A 100 microL plasma sample was extracted with ethyl acetate. B7T and the internal standard (IS), pimozide, in the samples were then analyzed with LC-MS/MS in positive electrospray ionization condition. Chromatographic separation of B7T and IS was achieved in a C(18) reversed-phase HPLC column (150 x 2.1 mm i.d.) by isocratic elution with a mobile phase consisting of 0.05% formic acid in water and acetonitrile (1:1, v/v) at a flow rate of 0.35 mL/min. Multiple-reaction monitoring (MRM) mode was employed to measure the ion transitions: m/z 247 to 197 for B7T and m/z 462 to m/z 328 for IS, respectively. The method was linear over the studied ranges of 100-5000 and 10-100 ng/mL. The intra-day and inter-day variations of the analysis were less than 6.8% with standard errors less than 9.0%. The detection limit of B7T in rat plasma was 1 ng/mL. The developed method was successfully applied to the pharmacokinetic study of B7T after intravenous administration of 1 mg/kg B7T and further proved to be readily utilized for determination of B7T in rat plasma samples.     

Quantitative determination of DRF-1042 in human plasma by HPLC: validation and application in clinical pharmacokinetics

A simple and sensitive high-performance liquid chromatography (HPLC) method has been developed and validated for the determination of DRF-1042, a novel orally active camptothecin (CPT) analog, in human plasma. The sample preparation was a simple deproteinization with acidified methanol yielding almost 100% recovery of DRF-1042. An isocratic reverse-phase HPLC separation was developed on a Supelcosil-LC318 column (250 x 4.6 mm, 5 microm) with mobile phase consisting of 1% v/v triethylamine acetate, pH 5.5 and acetonitrile (80:20, v/v) at a fl ow rate of 1.0 mL/min. The eluate was monitored with a fluorescence detector set at excitation and emission wavelengths of 370 and 430 nm, respectively. The standard curves were linear (r(2) > 0.999) in the concentration ranges 5.0-2004 ng/mL. The lower limit of quantification (LLQ) of the assay was 5 ng/mL. The mean measured quality control (QC) concentrations (range 5 ng/mL to 40 microg/mL) deviated from the nominal concentrations in the range of -10.5-0.08 and -14.5-7.97%, inter- and intra-day, respectively. The inter- and intra-day precisions in the measurement of QC samples at four tested concentrations, were in the range 0.64-5.89% relative standard deviation (RSD) and 0.33-14.7% RSD, respectively. The method was found to be suitable for measurement of plasma concentrations above the calibration curve after serial dilutions. Stability of DRF-1042 was confirmed in a battery of studies, viz., on bench-top, in the auto-sampler, in the stock solutions, after four quick freeze-thaw cycles, up to one month at -20 degree C in human plasma and up to 2 months in the ex vivo samples. The method is simple, sensitive and reliable and has been successfully implemented to investigate the clinical pharmacokinetics of DRF-1042 in cancer patients in a phase I clinical trial.     

A validated high-performance liquid chromatographic assay for determination of lumiracoxib in human plasma

Lumiracoxib {2-[(2-fluoro-6-chlorophenyl)amino]-5-methyl-benzeneacetic acid} is a highly selective and potent cyclooxygenase-2 (COX-2) inhibitor, which is chemically distinct from other coxibs in that it contains a carboxylic group and is weakly acidic. In the present study, a liquid-liquid extraction-based reversed-phase HPLC method with UV detection was validated and applied for the analysis of lumiracoxib in human plasma. The analyte was separated on a reversed-phase column with acetonitrile and 0.05% trichloracetic acid in water (35:65, v/v) as mobile phase at a flow rate of 1 mL/min, and UV detection at 270 nm. The retention times for lumiracoxib and niflumic acid (internal standard) were 16.9 and 10.4 min, respectively. The validated quantitation range for lumiracoxib was 10-10,000 ng/mL. The developed procedure was applied to assess the pharmacokinetics of lumiracoxib following administration of a single oral 200 mg dose to a healthy male volunteer.     

A sensitive LC–MS/MS‐based bioanalytical method for quantification of salviaflaside and rosmarinic acid in rat plasma and its application in a pharmacokinetic study

A selective and sensitive liquid chromatography tandem mass spectrometry method was developed for the simultaneous determination of salviaflaside and rosmarinic acid in rat plasma. Sample preparation was carried out through liquid–liquid extraction with ethyl acetate using curculigoside as internal standard (IS). The analytes were determined by selected reaction monitoring operated in the positive ESI mode. Chromatographic separation was performed on an Agilent Eclipse Plus C₁₈ column (100 × 4.6 mm, 1.8 μm) with a mobile phase consisting of methanol–water–formic acid (50:50:0.1, v/v/v) at a flow rate of 0.3 mL/min. The run time was 1.9 min per sample and the injection volume was 5 μL. The method had an LLOQ of 1.6 ng/mL for salviaflaside and 0.94 ng/mL for rosmarinic acid in plasma. The linear calibration curves were fitted over the range of 1.6–320 ng/mL for salviaflaside and 0.94–188 ng/mL for rosmarinic acid in plasma with correlation coefficients (r²) >0.99. Intra‐ and inter‐day precisions (relative standard deviation) were < 13.5%, and accuracies (relative error) were between −8.6% and 14.5% for all quality control samples. The method was validated and applied to the pharmacokinetics of salviaflaside and rosmarinic acid in plasma after oral administration of Prunella vulgaris extract to rats.     

Simultaneous determination of udenafil and its active metabolite, DA-8164, in human plasma and urine using ultra-performance liquid chromatography-tandem mass spectrometry: application to a pharmacokinetic study

A rapid, sensitive, and simple ultra-performance liquid chromatography-tandem mass spectrometry (UPLC/MS/MS) method for the determination of udenafil and its active metabolite, DA-8164, in human plasma and urine using sildenafil as an internal standard (IS) was developed and validated. Udenafil, DA-8164 and IS from a 100 microL aliquot of biological samples were extracted by protein precipitation using acetonitrile. Chromatographic separation was carried on an Acquity UPLC BEH C(18) column (50 x 2.1 mm, i.d., 1.7 microm) with an isocratic mobile phase consisting of acetonitrile and containing 0.1% formic acid (75:25, v/v) at flow rate of 0.4 mL/min, and total run time was within 1 min. Detection and quantification was performed by the mass spectrometer using multiple reaction-monitoring mode at m/z 517 --> 283 for udenafil, m/z 406 --> 364 for DA-8164 and m/z 475 --> 100 for IS. The assay was linear over a concentration range of 1-600 ng/mL with a lower limit of quantification of 1 ng/mL in both human plasma and urine. The coefficient of variation of this assay precision was less than 13.7%, and the accuracy exceeded 92.0%. This method was successfully applied for pharmacokinetic study after oral administration of udenafil 100 mg to healthy Korean male volunteers.     

Simultaneous determination of niacin and its metabolites—nicotinamide,nicotinuric acid and N‐methyl‐2‐pyridone‐5‐carboxamide—in human plasma by LC‐MS/MS and its application to a human pharmacokinetic study

An LC‐MS/MS method for the simultaneous quantitation of niacin (NA) and its metabolites, i.e. nicotinamide (NAM), nicotinuric acid (NUA) and N‐methyl‐2‐pyridone‐5‐carboxamide (2‐Pyr), in human plasma (1 mL) was developed and validated using nevirapine as an internal standard (IS). Extraction of the NA and its metabolites along with the IS from human plasma was accomplished using a simple liquid–liquid extraction. The chromatographic separation of NA, NAM, NUA, 2‐Pyr and IS was achieved on a Hypersil‐BDS column (150 ¥ 4.6 mm, 5 mm) column using a mobile phase consisting of 0.1% formic acid : acetonitrile (20:80 v/v) at a flow rate of 1 mL/min. The total run time of analysis was 2 min and elution of NA, NAM, NUA, 2‐Pyr and IS occurred at 1.37, 1.46, 1.40, 1.06 and 1.27 min, respectively. A detailed validation of the method was performed as per the FDA guidelines and the standard curves were found to be linear in the range of 100–20000 ng/mL for NA; 10–1600 ng/mL for NUA and NAM and 50–5000 ng/mL for 2‐Pyr with mean correlation coefficient of ≥0.99 for each analyte. The method was sensitive, specific, precise, accurate and suitable for bioequivalence and pharmacokinetic studies. The developed assay method was successfully applied to a pharmacokinetic study in humans. Copyright © 2010 John Wiley & Sons, Ltd.     

Development and validation of a rapid ultra high performance liquid chromatography with tandem mass spectrometry method for the simultaneous determination of darunavir,ritonavir, and tenofovir in human plasma: Application to human pharmacokinetics

A sensitive ultra high performance liquid chromatography with tandem mass spectrometry method was developed for the simultaneous determination of darunavir, ritonavir and tenofovir in human plasma. Sample preparation involved a simple liquid–liquid extraction using 200 μL of human plasma extracted with methyl tert‐butyl ether for three analytes and internal standard. The separation was accomplished on an Acquity UPLC BEH C₁₈ (50 mm x 2.1 mm, 1.7 μm) analytical column using gradient elution of acetonitrile/methanol (80:20, v/v) and 5.0 mM ammonium acetate containing 0.01% formic acid at a flow rate of 0.4 mL/min. The linearity of the method ranged between 20.0 and 12 000 ng/mL for darunavir, 2.0 and 2280 ng/mL for ritonavir, and 14.0 and 1600 ng/mL for tenofovir using 200 μL of plasma. The method was completely validated for its selectivity, sensitivity, linearity, precision and accuracy, recovery, matrix effect, stability, and dilution integrity. The extraction recoveries were consistent and ranged between 79.91 and 90.04% for all three analytes and internal standard. The method exhibited good intra‐day and inter‐day precision between 1.78 and 6.27%. Finally the method was successfully applied for human pharmacokinetic study in eight healthy male volunteers after the oral administration of 600 mg darunavir along with 100 mg ritonavir and 100 mg tenofovir as boosters.     

A reversed-phase high-performance liquid chromatographic method for the determination of zafirlukast in pharmaceutical formulations and human plasma

Zafirlukast (ZAF) is a leukotriene receptor antagonist used in the treatment of chronic asthma. In this study, a simple and sensitive reversed-phase, high-performance liquid chromatographic method was developed for the determination of ZAF in pharmaceutical formulations and human plasma. Piribedil was used as an internal standard. Analysis was carried out on a Nucleosil C18 100 A (150 mm x 4.6 mm id, 5 Vm) column with acetonitrile-pH 3.0 acetate buffer (70 + 30, v/v) as the mobile phase at a flow rate of 0.8 mL/min. The peak was detected by an ultraviolet detector set at a wavelength of 240 nm. The retention times were about 3.9 min for piribedil and 5.8 min for ZAF. The developed method was applied to the determination of ZAF in its pharmaceutical formulation and spiked human plasma. For quantification of ZAF in spiked plasma, proteins were precipitated with ethanol before chromatographic analysis. The calibration range was linear from 49.69-437.50 ng/mL in spiked plasma. The absolute recovery from spiked plasma was 98.73 +/- 0.42% at a concentration of 254.78 ng/mL of ZAF. No endogenous substances from plasma were found to interfere.     

Enantioselective determination of arotinolol in human plasma by HPLC using teicoplanin chiral stationary phase

A sensitive enantioselective high-performance liquid chromatography (HPLC) method was developed and validated to determine S-(+)- and R-(-)-arotinolol in human plasma. Baseline resolution was achieved by using teicoplanin macrocyclic antibiotic chiral stationary phase (CSP) known as Chirobiotic T with a polar organic mobile phase consisting of methanol:glacial acetic acid:triethylamine, 100:0.1:0.1, (v/v/v) at a fl ow rate of 0.8 mL/min and UV detection set at 317 nm. Human plasma was spiked with stock solution of arotinolol enantiomers and labetalol as the internal standard. The assay involved the use of liquid-liquid extraction procedure with ethyl ether under alkaline condition for human plasma sample prior to HPLC analysis. Recoveries for S-(+)- and R-(-)-arotinolol enantiomers were in the range 93-103% at 200-1400 ng/mL level. Intra-day and inter-day precision calculated as %RSD was in the ranges 1.3-3.4 and 1.9-4.5% for both enantiomers, respectively. Intra-day and inter-day accuracies calculated as percentage error were in the ranges 1.2-3.5 and 1.5-6.2% for both enantiomers, respectively. Linear calibration curves in the concentration range 100-1500 ng/mL for each enantiomer showed a correlation coefficient (r) of 0.9998. The limit of quantitation (LOQ) and limit of detection (LOD) for each enantiomer in human plasma were 100 and 50 ng/mL (S/N = 3), respectively.     

Determination of ranolazine in human plasma by liquid chromatographic-tandem mass spectrometric assay

A highly sensitive liquid chromatographic-tandem mass spectrometric method (LC-MS-MS) is developed to quantitate ranolazine in human plasma. The analyte and internal standard tramadol are extracted from plasma by liquid-liquid extraction using diethyl ether-dichloromethane (60:40 v/v), and separated on a Zorbax extend C(18) column using methanol-10mM ammonium acetate (60:40 v/v, pH 4.0) at a flow of 1.0 mL/min. Detection is carried out by multiple reaction monitoring on a QtrapTM LC-MS-MS system with an electrospray ionization interface. The assay is linear over the range 10-5000 ng/mL with a limit of quantitation of 10 ng/mL and a lower limit of detection (S/N > 3) of 1 ng/mL. Intra- and inter-day precision are < 3.1% and < 2.8%, respectively, and the accuracy is in the range 96.7-101.6%. The validated method is successfully used to analyze the drug in samples of human plasma for pharmacokinetic studies.     

Development and validation of a liquid chromatographic/tandem mass spectrometric method for determination of tetracycline in human plasma: application to bioequivalence study

A fast, sensitive, and specific liquid chromatographic/tandem mass spectrometric method was developed and validated for determination of tetracycline in human plasma. Tetracycline and oxytetracycline [internal standard (IS)] were extracted from the plasma by protein precipitation. The mobile phase consisted of acetonitrile-formic acid 0.1% (48 + 52, v/v), run at a flow rate of 1 ml/min (split 1:5). Detection was performed by positive electrospray ionization in multiple reaction monitoring mode, monitoring the transitions 444.8 > 410.0 and 461.0 > 426.0 for tetracycline and IS, respectively. The analysis was performed in 3.5 min and the method was linear in the plasma concentration range of 50-6000 ng/mL. The mean extraction recoveries for tetracycline and IS from plasma were 92.14 and 94.04%, respectively. Method validation investigated parameters such as the linearity, precision, accuracy, specificity, and stability, giving results within the acceptable range. The proposed method was successfully applied for determination of tetracycline in human plasma samples to support bioequivalence studies.     

High-throughput determination of atrasentan in human plasma by high-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry

Atrasentan (A-147627) is an endothelin antagonist receptor being developed at Abbott Laboratories for the treatment of prostate cancer. A quick and sensitive method for the determination of atrasentan in human plasma has been developed and validated using high-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry. A dual-column, single mass spectrometer system is used to provide a reliable and routine means to increase sample throughput. The analytical method involves liquid-liquid extraction and internal standard (A-166790). The plasma samples and internal standard are acidified with 0.3 M hydrochloric acid prior to being extracted into 1:1 (v/v) hexanes--methyl t-butyl ether. The organic extract was evaporated to dryness using heated nitrogen stream and reconstituted with mobile phase. Atrasentan and internal standard were separated with no interference in a Zorbax SB-C(18) analytical column with 2.1 x 50 mm, 5 microm, and a Zorbax C(8) guard column using a mobile phase consisting of 50:50 (v:v) acetonitrile--0.05 M ammonium acetate, pH 4.5, at a flow rate of 0.30 mL/min to provide 4 min chromatograms. For a 250 microL plasma sample volume, the limit of quantitation was approximately 0.3 ng/mL. The calibration was linear from 0.30 to 98.0 ng/mL (r(2) > 0.995). A significant advantage of the method is the ability to employ parallel HPLC separations with detection by a single MS/MS system to provide sensitivity and selectivity sufficient to achieve robust analytical results with a lower limit of quantitation of 0.30 ng/mL and high throughput.     

Determination of metoprolol in human plasma and urine by high‐performance liquid chromatography with fluorescence detection

A simple, specific and sensitive HPLC method has been developed for the determination of metoprolol in human plasma and urine. Separation of metoprolol and atenolol (internal standard) was achieved on an Ace C₁₈ column (5 μm, 250 mm×4.6 mm id) using fluorescence detection with λ_ex=276 nm and λ_em=296 nm. The mobile phase consists of methanol–water (50:50, v/v) containing 0.1% TFA. The analysis was performed in less than 10 min with a flow rate of 1 mL/min. The assay was linear over the concentration range of 3 – 200 and 5 – 300 ng/mL for plasma and urine, respectively. The LOD were 1.0 and 1.5 ng/mL for plasma and urine, respectively. The LOQ were 3.0 and 5.0 ng/mL for plasma and urine, respectively. The extraction recoveries were found to be 95.6 ± 1.53 and 96.4 ± 1.75% for plasma and urine, respectively. Also, the method was successfully applied to three patients with hypertension who had been given an oral tablet of 100 mg metoprolol.     

Quantitative analysis of the farnesyl transferase inhibitor lonafarnib (Sarasartrade mark, SCH66336) in human plasma using high-performance liquid chromatography coupled with tandem mass spectrometry

Lonafarnib is a novel anticancer drug that inhibits farnesyl transferase. To assess its pharmacokinetic properties, we developed a sensitive and quantitative assay using liquid chromatography coupled with tandem mass spectrometry for the determination of lonafarnib levels in human plasma. Sample pretreatment consisted of the addition of an isotopically labeled internal standard and protein precipitation with acetonitrile using 100 microL plasma. Chromatographic separation was performed on an Inertsil ODS-3 analytical column (50 x 2.1 mm i.d., particle size 5 microm) with acetonitrile/water/formic acid (50:50:0.05, v/v/v) as the mobile phase, at a flow rate of 0.2 mL/min. The analytical run time was 8 min. An API365 triple quadrupole mass spectrometer was used for specific and sensitive detection. It was operated in the positive ion mode and multiple reaction monitoring was used for drug quantification. The method was validated using a concentration range of 2.5 to 2500 ng/mL lonafarnib. Validation of the assay was performed according to the most recent FDA guidelines for bioanalytical method validation and all results were within the requirements. The described method was successfully applied to support a clinical phase I trial with lonafarnib.     

A rapid, sensitive high performance liquid chromatographic method for the determination of meropenem in pharmaceutical dosage form, human serum and urine.

A new, simple, precise and rapid high performance liquid chromatographic method was developed for the determination of meropenem in human serum, urine and pharmaceutical dosage forms. Chromatography was carried out on an LC(18) column using a mixture of 15 mM KH(2)PO(4):acetonitrile:methanol (84:12:4; v/v/v), adjusted to pH 2.8 with H(3)PO(4). The proposed method was conducted using a reversed-phase technique, UV monitoring at 307.6 nm and cefepime as an internal standard. The retention times were 5.98 and 7.47 min for cefepime and meropenem, respectively. The detector response was linear over the concentration range of 50-10,000 ng/mL. The detection limit of the procedure was found to be 22 ng/mL. The detection limit for meropenem in human plasma was 108.4 ng/mL and the corresponding value in human urine was 179.3 ng/mL. No interference from endogenous substances in human serum, urine and pharmaceutical preparation was observed. The proposed method is sufficiently sensitive for determination of the concentrations of meropenem and may have clinical application for its monitoring in patients receiving the drug.     

超高效液相色谱-三重四极杆质谱联用方法测定血浆和尿液中的α-龙葵碱、α-卡茄碱和茄啶

建立了超高效液相色谱-三重四极杆质谱联用方法,检测血浆和尿液中的α-龙葵碱、α-卡茄碱和茄啶。样品经2%(v/v,下同)甲酸水溶液等量稀释,再经混合型阳离子交换固相萃取柱(MCX SPE)净化,以0.1%甲酸乙腈溶液和含0.05%甲酸的5 mmol/L乙酸铵水溶液作为流动相进行梯度洗脱,在UPLC BEH C18色谱柱上实现分离,正离子电喷雾串联质谱多反应监测(ESI-MS/MS MRM)方式检测,基质匹配外标法定量。一次进样分析时间为5.5min。血浆和尿液中3种待测物的线性范围均为0.3~100 ng/mL,相关系数为0.997~0.999;样品的检出限为0.1 ng/mL,定量限为0.3 ng/mL;血浆和尿液中的平均加标回收率分别为82%~112%和96%~114%,相对标准偏差为4.0%~16%和2.7%~17%(n=6)。方法简单、准确、灵敏,适用于马铃薯中毒检测。