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. , Hoffmann , L. , and Bohn , T. ( 2010 ). Development of a multi-class method for the quantification of veterinary drug residues in feedingstuffs by liquid chromatography-tandem mass spectrometry . Journal of Chromatography A , 1217 : 6394 – 6404 . 10

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sensitivity and selectivity. Recently, however, the outstanding selectivity, speed, and sensitivity, liquid chromatography combined with electrospray ionization tandem mass spectrometry based on a triple quadruple configuration has been used for the

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Abstract  

The chemical form of the retention of TcN/et2dtc/2 has been investigated by mass spectrometry. The results indicate that this complex does not undergo ligand exchange reactions with plasma proteins.

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Summary

A sensitive and selective liquid chromatographic tandem mass spectrometric (LC-MS-MS) method for analysis of lovastatin in human plasma has been developed and validated. Ethyl acetate extraction was used for plasma sample preparation and simvastatin was used as internal standard. Chromatographic separation was achieved on a C18 column by isocratic elution with 83:17:0.1 (v/v) methanol-2 μM aqueous sodium acetate-formic acid as mobile phase, delivered at 1.0 mL min−1. MS-MS detection was performed using positive electrospray ionization and multiple-reaction monitoring with argon for collision-induced dissociation. Calibration plots were generated over the concentration range 0.05 to 20 ng mL−1 (r > 0.999) with a lower limit of quantification (LLOQ) of 0.05 ng mL−1. Intra and inter-day precision and accuracy were determined at four different concentrations, 0.05, 0.5, 2.0, and 10.0 ng mL−1, and precision ranged from 0.4 to 11.4% with the deviation always less than 15% (n = 5). Extraction recoveries were from 86.8 to 94.1% for lovastatin and approximately 88.0% for simvastatin. The validated method was successfully applied to a bioequivalence study of two lovastatin tablets in 20 healthy volunteers.

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Summary

A simple and rapid method, using online ultraperformance liquid chromatography with photodiode array detection and electrospray ionization mass spectrometry (UPLC-PDA-eλ-ESI-MS/MS), was developed for the in-depth analysis of 50 batches Radix et Rhizoma Rhei. The analysis was performed on a UPLC BEH C18 column using a gradient elution system. Baseline separation could be achieved in less than 7.5 min. At the same time, on the basis of the 50 batches of samples collected from representative cultivated regions, a novel chromatographic fingerprint was devised by UPLC-PDA, in which 27 common peaks were detected and identified by the developed UPLC-MS/MS method step by step according to fragmentation mechanisms, MS/MS data, standards, and relevant literature. Many active components gave prominent [M - H] ions in the ESI mass spectra. These components include anthraquinones, sennosides, stilbenes, glucose gallates, naphthalenes, and catechins. Furthermore, based on the information of these Radix et Rhizoma Rhei components, and further combined with discriminant analysis, a novel discriminant analysis equation (DAE) was established for the quality control of Radix et Rhizoma Rhei for the first time.

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Summary

Capsaicin has been reported to exhibit an inhibitory effect on the P-glycoprotein (P-gp) function in vitro. To investigate its concentration-dependent effect in vivo, a sensitive assay that can characterize the absorption and disposition of capsaicin needs to be developed. This study reports the development of a sensitive LC-MS/MS assay for the determination of capsaicin in mouse plasma. The sample pretreatment involved a one-step extraction of 20 μL plasma with t-butyl methyl ether. Separations were achieved on a C18 column and the detection was performed on an LC-ESI-MS/MS by multiple reaction monitoring. The assay was linear over a wide concentration range from 0.325 to 650 ng mL−1 (r > 0.999), with a LLOQ of 0.325 ng mL−1. The developed method was applied to i.v. (dose 0.325 and 0.65 mg kg) and oral absorption (dose 40 mg kg) studies in mice. After i.v. injection, the t 1/2,λz, V z and CL s ranged from 0.13–0.16 h, 127.6–141.8 mL, and 547.3–775.4 mL/h, respectively. After oral administration, a secondary peak was observed and the terminal half-life was prolonged (1.51 h). Capsaicin was poorly absorbed, with the absolute oral bioavailability (F) ranging from 1.02% to 1.56%. The developed assay may be useful in studies where sample volumes are limited.

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Summary

A sensitive and specific high-performance liquid chromatographic-electrospray ionization tandem mass spectrometric (HPLC-ESI-MS-MS) method for quantification of tamsulosin in human plasma, using propranolol as internal standard (IS), has been developed, validated successfully, then used in a clinical study. Plasma (0.5 mL) was mixed with 50 μL 1 m sodium carbonate solution. Tamsulosin and propranolol were isolated from the mixture by liquid-liquid extraction with 7:3 (v/v) hexane-ethyl acetate. Reversed-phase chromatography was performed on a C8 column at 25°C with 70:30:0.1 (v/v) methanol-water-formic acid as mobile phase at a flow-rate of 1.0 mL min−1. Quantification was achieved in positive-ion mode by monitoring the product ions at m/z 409.1 → 270.9, 228.0, and 200.0 (tamsulosin) and m/z 260.1 → 183.0 (IS). The lowest limit of quantification was 0.25 ng mL−1, and the calibration range was 0.25–50 ng mL−1. Within and between batch precision (expressed as coefficient of variation, CV) did not exceed 10.8% and accuracy was within 5.0% deviation of the nominal concentration. Recovery of tamsulosin from plasma was >83.0%. The validated method was used for clinical study of tamsulosin in human volunteers.

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Abstract

Eugenitin is a non-volatile chromone derivative which is always found in dried flower buds of Syzygium aromaticum L. (Merr.) & L.M. Perry. Until now, there were no reports about the pharmacokinetics of eugenitin in biological fluids. A UPLC-MS/MS method developed to determine eugenitin in mouse blood. The blood samples were prepared by protein precipitation with acetonitrile. Chrysin (internal standard, IS) and eugenitin were gradient eluted by mobile phase of acetonitrile and water (0.1% formic acid) in a BEH C18 column. The multiple reaction monitoring (MRM) of m/z 221.1→206.0 for eugenitin and m/z 255.1→152.9 for IS with an electrospray ionization (ESI) source was used for quantitative detection. The calibration curve ranged from 0.5 to 500 ng/mL (r > 0.995). The accuracy ranged from 98 to 113%, the precision was less than 12%, and the matrix effect was between 86 and 94%, the recovery was better than 81%. The developed method was successfully used for pharmacokinetics of eugenitin in mice after intravenous (5 mg/kg) and oral (20 mg/kg) administration, and the absolute availability of eugenitin was 12%.

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A new, sensitive, and selective high-performance liquid chromatography-tandem mass spectrometric method (HPLC-MS/MS) has been developed for the quantification of six flavonoids (sophoricoside, genistin, genistein, rutin, quercetin, and kaempferol) in rat bile and urine. The sample pretreatment was simple by liquid-liquid extraction. Sulfamethalazole was used as internal standard (IS). During method development, the effect of extraction volume, mobile phase composition, column temperature, and injection volume were varied to optimize sensitivity and achieve a run time as short as possible. Chromatographic separation was accomplished on a C18 column with a simple linear gradient elution within 9 min. Full validation of the assay was in accordance with the requirement of the validation of the method in vivo and implemented including specificity, linearity, accuracy, precision, recovery, and matrix effect. This is the first report on determination of the major flavones in rat bile and urine after oral administration of Fructus Sophorae extract. The method has been used successfully in excretion studies of six major flavonoids in rat bile and urine.

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An accurate and rapid liquid chromatography–electrospray ionizaion– tandem mass spectrometry (LC—ESI—MS/MS) analytical method was developed and validated for the simultaneous determination of antcins A, B, C, H, and K, dehydroeburicoic acid, and 4,7-dimethoxy-5-methyl-1,3-benzodioxole in the extract and capsule of Antrodia cinnamomea (AC) fruiting body. These seven signature compounds were ionized using an electrospray ion source and analyzed by a triple-quadrupole mass analyzer under a multiple reaction monitoring (MRM) mode. The MRM transitions of m/z 453/409 (antcin A), m/z 467/408 (antcin B), m/z 469/425 (antcin C), m/z 485/413 (antcin H), m/z 487/407 (antcin K), m/z 467/337 (dehydroeburicoic acid), and m/z 197/139 (4,7-dimethoxy-5-methyl-1,3-benzodioxole) were used to quantify these seven components, respectively. Their calibration curves presented good linear regressions (R 2 > 0.997) within the tested concentration range. The intra- and inter-day precisions were less than 1.97% and 2.53%, respectively. The overall recovery was in the range of 87.55%–95.41%. This validated high-performance liquid chromatography (HPLC)—MS/MS method offers promising applications for the accurate and rapid quantification of signature compounds in the fruiting body and its commercial products.

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