A new issue of this journal has just
been published. To see abstracts of the papers it contains (with links through
to the full papers) click here:
Selected
papers from the latest issue:
Determination of Pseudoginsengenin DQ in rat plasma by UPLC–MS/MS and application of the method in a pharmacokinetic study
17 July 2013,
15:23:06
Publication date: 15 August
2013
Source:Journal of Chromatography B, Volume 933
Author(s): Hongmei Gao , Zhuo Li , Pingya Li , Meiyu Lin , Liu Han , Fang Wang , Jinping Liu
Pseudoginsengenin DQ (pseudoginsengenin of diol derivatives quest, PDQ), the product of the oxidative cyclization of protopanaxadiol, exhibits a significant pharmacological effect as an antiarrhythmic agent. A sensitive and rapid analytical method based on ultra-performance liquid chromatography coupled with tandem mass spectrometry (UPLC–MS/MS) was initially developed for the detection of PDQ in rat plasma. Pre-treatment of the sample obtained from the plasma involved a single protein precipitation step, using methanol. PDQ and an internal standard (IS), physcion, were separated on a Waters ACQUITY UPLC BEH C18 analytical column (50mm×2.1mm, 1.7μm) using acetonitrile-0.1% formic acid in water (70:30, v/v) as the mobile phase, at a flow rate of 0.3mL/min. Chromatography of the PDQ and IS was performed within 3min. Detection was performed through positive ion electrospray ionization (ESI+) in multiple reaction-monitoring (MRM) mode. The assay was linear over the concentration range of 5–1000ng/mL (r >0.9980). The limit of detection (LOD) and the lower limit of quantification (LLOQ) were 0.5ng/mL and 5.0ng/mL, respectively. The intra- and inter-day deviations (expressed as relative standard deviation, RSD) were ≤9.5% and ≤1.7%, respectively, and the accuracy (expressed as relative error, RE) was in the range of −1.1 to 2.7%. The recoveries of PDQ and IS were 95.2% and 100.7%, respectively, and the matrix effects were satisfactory in all of the biological matrices examined. This fully validated method was successfully applied to the pharmacokinetic study of rats after a single initial intragastric administration of 15mg/kg PDQ. The main pharmacokinetic parameters: T max (the time to peak), C max (the concentration to peak), and t 1/2 (the biological half time) were 4.0±0.0h, 3265.12±700.26ng/mL, 5.97±0.43h, respectively.
Source:Journal of Chromatography B, Volume 933
Author(s): Hongmei Gao , Zhuo Li , Pingya Li , Meiyu Lin , Liu Han , Fang Wang , Jinping Liu
Pseudoginsengenin DQ (pseudoginsengenin of diol derivatives quest, PDQ), the product of the oxidative cyclization of protopanaxadiol, exhibits a significant pharmacological effect as an antiarrhythmic agent. A sensitive and rapid analytical method based on ultra-performance liquid chromatography coupled with tandem mass spectrometry (UPLC–MS/MS) was initially developed for the detection of PDQ in rat plasma. Pre-treatment of the sample obtained from the plasma involved a single protein precipitation step, using methanol. PDQ and an internal standard (IS), physcion, were separated on a Waters ACQUITY UPLC BEH C18 analytical column (50mm×2.1mm, 1.7μm) using acetonitrile-0.1% formic acid in water (70:30, v/v) as the mobile phase, at a flow rate of 0.3mL/min. Chromatography of the PDQ and IS was performed within 3min. Detection was performed through positive ion electrospray ionization (ESI+) in multiple reaction-monitoring (MRM) mode. The assay was linear over the concentration range of 5–1000ng/mL (r >0.9980). The limit of detection (LOD) and the lower limit of quantification (LLOQ) were 0.5ng/mL and 5.0ng/mL, respectively. The intra- and inter-day deviations (expressed as relative standard deviation, RSD) were ≤9.5% and ≤1.7%, respectively, and the accuracy (expressed as relative error, RE) was in the range of −1.1 to 2.7%. The recoveries of PDQ and IS were 95.2% and 100.7%, respectively, and the matrix effects were satisfactory in all of the biological matrices examined. This fully validated method was successfully applied to the pharmacokinetic study of rats after a single initial intragastric administration of 15mg/kg PDQ. The main pharmacokinetic parameters: T max (the time to peak), C max (the concentration to peak), and t 1/2 (the biological half time) were 4.0±0.0h, 3265.12±700.26ng/mL, 5.97±0.43h, respectively.
Examination of 1-methylimidazole series ionic liquids in the extraction of flavonoids from Chamaecyparis obtuse leaves using a response surface methodology
17 July 2013,
15:23:06
Publication date: 15 August
2013
Source:Journal of Chromatography B, Volume 933
Author(s): Baokun Tang , Yu Jin Lee , Yu Ri Lee , Kyung Ho Row
Ionic liquids (ILs) are a new type of reagent that has accelerated research in extraction technology. On the other hand, few studies have systematically applied 1-methylimidazole ([MIM]) series ILs to the extraction of bioactive compounds from plants. In this study, [MIM] series ILs were used to extract four bioactive flavonoids, such as dihydrokaempferol, quercitrin, amentoflavone and myricetin, from Chamaecyparis obtuse (CO) leaves. First, a screen of the extraction method and solvent revealed the [MIM] series ILs to be suitable as additives in methanol in Soxhlet extraction. Second, an examination of a range of cations and anions of [MIM] series ILs for extraction revealed 1-decyl-3-methylimidazolium bromide ([DMIM][Br]) to be the best selection as an additive in methanol for the Soxhlet extraction of flavonoids from (CO) leaves. Finally, some factors of extraction, such as temperature, time and amount of samples, were examined systematically using a response surface methodology (RSM). Based on the above optimization, 2.41, 3.47, 0.76 and 3.15mg/g of dihydrokaempferol, quercitrin, amentoflavone and myricetin, respectively, were extracted from 15g of CO leaves by 2.5mgmL−1 of [DMIM][Br] as additives in 200mL of methanol in Soxhlet extraction at 200°C for 8h. This study highlights the potential of [MIM] series ILs as promising reagents for the extraction of bioactive compounds from plants.
Source:Journal of Chromatography B, Volume 933
Author(s): Baokun Tang , Yu Jin Lee , Yu Ri Lee , Kyung Ho Row
Ionic liquids (ILs) are a new type of reagent that has accelerated research in extraction technology. On the other hand, few studies have systematically applied 1-methylimidazole ([MIM]) series ILs to the extraction of bioactive compounds from plants. In this study, [MIM] series ILs were used to extract four bioactive flavonoids, such as dihydrokaempferol, quercitrin, amentoflavone and myricetin, from Chamaecyparis obtuse (CO) leaves. First, a screen of the extraction method and solvent revealed the [MIM] series ILs to be suitable as additives in methanol in Soxhlet extraction. Second, an examination of a range of cations and anions of [MIM] series ILs for extraction revealed 1-decyl-3-methylimidazolium bromide ([DMIM][Br]) to be the best selection as an additive in methanol for the Soxhlet extraction of flavonoids from (CO) leaves. Finally, some factors of extraction, such as temperature, time and amount of samples, were examined systematically using a response surface methodology (RSM). Based on the above optimization, 2.41, 3.47, 0.76 and 3.15mg/g of dihydrokaempferol, quercitrin, amentoflavone and myricetin, respectively, were extracted from 15g of CO leaves by 2.5mgmL−1 of [DMIM][Br] as additives in 200mL of methanol in Soxhlet extraction at 200°C for 8h. This study highlights the potential of [MIM] series ILs as promising reagents for the extraction of bioactive compounds from plants.
Development of a simple method for simultaneous determination of nine subclasses of non-steroidal anti-inflammatory drugs in milk and dairy products by ultra-performance liquid chromatography with tandem mass spectrometry
17 July 2013,
15:23:06
Publication date: 15 August
2013
Source:Journal of Chromatography B, Volume 933
Author(s): Tao Peng , Ai-Ling Zhu , Yue-Ning Zhou , Ting Hu , Zhen-Feng Yue , Dong-Dong Chen , Guo-Min Wang , Jian Kang , Chun-lin Fan , Ying Chen , Hai-Yang Jiang
A multi-residue analysis method for simultaneous determination of nine subclasses of non-steroidal anti-inflammatory drugs (NSAIDs) in milk and dairy products by ultra-performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) has been established. The sample was initially extracted and deproteinized with ascorbic acid buffer (0.01M, pH 3) and acetonitrile–ethyl acetate mixture, followed by centrifugation and evaporation, then reconstituted with acetonitrile-0.1% formic acid (1+1, v/v). After removal of lipid material by n-hexane, the sample was analyzed by UPLC–MS/MS with electro-spray ionization (ESI) interface in Multiple Reaction Monitoring (MRM) mode. The range of limits of detection (LODs) and limits of quantification (LOQs) were 0.03–0.30μg/kg and 0.10–1.00μg/kg, respectively. The recoveries in milk, milk powder, yogurt, processed cheese and milk beverage ranged from 61.7% to 117%, and the relative standard deviations (RSDs) were less than 17.9% at three spiked levels (1, 10 and 100 times of the LOQ). Matrix effects were also investigated and it was determined the signals of the analytes were suppressed from 9.4% to 76.6% in processed cheese. The proposed method was also applied to incurred sample analysis. The results proved that this method was suitable for the simultaneous determination of nine subclasses of NSAIDs residues in milk and dairy products.
Source:Journal of Chromatography B, Volume 933
Author(s): Tao Peng , Ai-Ling Zhu , Yue-Ning Zhou , Ting Hu , Zhen-Feng Yue , Dong-Dong Chen , Guo-Min Wang , Jian Kang , Chun-lin Fan , Ying Chen , Hai-Yang Jiang
A multi-residue analysis method for simultaneous determination of nine subclasses of non-steroidal anti-inflammatory drugs (NSAIDs) in milk and dairy products by ultra-performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) has been established. The sample was initially extracted and deproteinized with ascorbic acid buffer (0.01M, pH 3) and acetonitrile–ethyl acetate mixture, followed by centrifugation and evaporation, then reconstituted with acetonitrile-0.1% formic acid (1+1, v/v). After removal of lipid material by n-hexane, the sample was analyzed by UPLC–MS/MS with electro-spray ionization (ESI) interface in Multiple Reaction Monitoring (MRM) mode. The range of limits of detection (LODs) and limits of quantification (LOQs) were 0.03–0.30μg/kg and 0.10–1.00μg/kg, respectively. The recoveries in milk, milk powder, yogurt, processed cheese and milk beverage ranged from 61.7% to 117%, and the relative standard deviations (RSDs) were less than 17.9% at three spiked levels (1, 10 and 100 times of the LOQ). Matrix effects were also investigated and it was determined the signals of the analytes were suppressed from 9.4% to 76.6% in processed cheese. The proposed method was also applied to incurred sample analysis. The results proved that this method was suitable for the simultaneous determination of nine subclasses of NSAIDs residues in milk and dairy products.
Highly sensitive HPLC method for assay of aliskiren in human plasma through derivatization with 1-naphthyl isocyanate using UV detection
17 July 2013,
15:23:06
Publication date: 15 August
2013
Source:Journal of Chromatography B, Volume 933
Author(s): F. Belal , M. Walash , N. El-Enany , S. Zayed
A simple and sensitive HPLC method has been developed for the determination of aliskiren in human plasma through derivatization with 1-naphthyl isocyanate. The separation was achieved on a C18 column using a mobile phase consisting of acetonitrile/water/phosphoric acid (45:55:0.01, v/v/v, pH 3.2) in a flow rate of 1mL/min with UV detection at 230nm. Caffeine was used as an internal standard. The factors influencing the derivatization reaction yields were carefully studied and optimized. The method was linear over the concentration range of 5–400ng/mL with a detection limit of 0.5ng/mL and a limit of quantification of 1.0ng/mL. The relative standard deviation was less than 4.2% for both intra-day assay and inter-day assay results. No interferences from endogenous compounds were encountered. The percentage recovery was in the range 97.1–98.6%. The method is suitable for routine therapeutic drug monitoring and for pharmacokinetic studies
Source:Journal of Chromatography B, Volume 933
Author(s): F. Belal , M. Walash , N. El-Enany , S. Zayed
A simple and sensitive HPLC method has been developed for the determination of aliskiren in human plasma through derivatization with 1-naphthyl isocyanate. The separation was achieved on a C18 column using a mobile phase consisting of acetonitrile/water/phosphoric acid (45:55:0.01, v/v/v, pH 3.2) in a flow rate of 1mL/min with UV detection at 230nm. Caffeine was used as an internal standard. The factors influencing the derivatization reaction yields were carefully studied and optimized. The method was linear over the concentration range of 5–400ng/mL with a detection limit of 0.5ng/mL and a limit of quantification of 1.0ng/mL. The relative standard deviation was less than 4.2% for both intra-day assay and inter-day assay results. No interferences from endogenous compounds were encountered. The percentage recovery was in the range 97.1–98.6%. The method is suitable for routine therapeutic drug monitoring and for pharmacokinetic studies
Modelling counter-current chromatography using a temperature dependence plate model
17 July 2013,
15:23:06
Publication date: 15 August
2013
Source:Journal of Chromatography B, Volume 933
Author(s): Yun Wei , Fengkang Wang , Shui Wang , Ying Zhang
So far, research workers have built several math models of counter-current chromatography (CCC), such as cell model, eluting counter-current distribution model, continuous-stirred tank reactors model, and probability model. Based on plate theory and Van’t Hoff equation, a new temperature dependence plate model has been established in this paper. When temperature was taken into consideration, the error of retention time was significantly reduced. The relationship between temperature and partition coefficient K can be summarized into linear equations (log K = A − B/T), which can be introduced to the plate model where A and B are constant and T is the temperature in Kelvin. K values decreased with the increasing temperature. Since resolution values (R) are related to K values, the change of temperature finally leads to the change of resolutions between different compounds. K values at different temperatures of a certain compound in a given system were calculated according to the equation above. New program with a temperature parameter was applied in prediction of experimental results, which diminished the error in modelling prediction. Besides, it is difficult for the CCC work when two compounds have similar K values. However, separation can be achieved by changing temperature, which can be directed by this new model.
Source:Journal of Chromatography B, Volume 933
Author(s): Yun Wei , Fengkang Wang , Shui Wang , Ying Zhang
So far, research workers have built several math models of counter-current chromatography (CCC), such as cell model, eluting counter-current distribution model, continuous-stirred tank reactors model, and probability model. Based on plate theory and Van’t Hoff equation, a new temperature dependence plate model has been established in this paper. When temperature was taken into consideration, the error of retention time was significantly reduced. The relationship between temperature and partition coefficient K can be summarized into linear equations (log K = A − B/T), which can be introduced to the plate model where A and B are constant and T is the temperature in Kelvin. K values decreased with the increasing temperature. Since resolution values (R) are related to K values, the change of temperature finally leads to the change of resolutions between different compounds. K values at different temperatures of a certain compound in a given system were calculated according to the equation above. New program with a temperature parameter was applied in prediction of experimental results, which diminished the error in modelling prediction. Besides, it is difficult for the CCC work when two compounds have similar K values. However, separation can be achieved by changing temperature, which can be directed by this new model.
LC-ESI-MS method for the determination of dexamethasone acetate in skin of nude mouse
17 July 2013,
15:23:06
Publication date: 15 August
2013
Source:Journal of Chromatography B, Volume 933
Author(s): Lingjun Li , Pengcheng Ma , Jun Wei , Kun Qian , Lei Tao
A high-performance liquid chromatography-positive electrospray ionization single quadrupole mass spectrometric (LC-ESI-MS) method for the determination of dexamethasone acetate in skin of nude mouse using triamcinolone acetonide acetate as the internal standard (I.S.) was developed and fully validated. Both compounds were precipitated from skin homogenate with methanol and were separated by HPLC on a Shimadzu Shim-pack VP-ODS C18 column (150mm×2.0mm, 5μm) with a mobile phase of methanol–water (80:20, v/v) at a flow rate of 0.2mL/min. Calibration curves were linear over the range of 0.05–5μg/mL. The intra-run relative standard deviations were less than 9.59%. The inter-run relative standard deviations were less than 7.82%. The mean recovery was in the ranges of 89.95–95.97%, respectively. The method was successfully applied to determinate the concentration of dexamethasone acetate in skin and study the percutaneous absorption process in skin of nude mouse.
Source:Journal of Chromatography B, Volume 933
Author(s): Lingjun Li , Pengcheng Ma , Jun Wei , Kun Qian , Lei Tao
A high-performance liquid chromatography-positive electrospray ionization single quadrupole mass spectrometric (LC-ESI-MS) method for the determination of dexamethasone acetate in skin of nude mouse using triamcinolone acetonide acetate as the internal standard (I.S.) was developed and fully validated. Both compounds were precipitated from skin homogenate with methanol and were separated by HPLC on a Shimadzu Shim-pack VP-ODS C18 column (150mm×2.0mm, 5μm) with a mobile phase of methanol–water (80:20, v/v) at a flow rate of 0.2mL/min. Calibration curves were linear over the range of 0.05–5μg/mL. The intra-run relative standard deviations were less than 9.59%. The inter-run relative standard deviations were less than 7.82%. The mean recovery was in the ranges of 89.95–95.97%, respectively. The method was successfully applied to determinate the concentration of dexamethasone acetate in skin and study the percutaneous absorption process in skin of nude mouse.
Development and validation of a sensitive LC–MS/MS method for the determination of fenoterol in human plasma and urine samples
17 July 2013,
15:23:06
Publication date: 15 August
2013
Source:Journal of Chromatography B, Volume 933
Author(s): M. Sanghvi , A. Ramamoorthy , J. Strait , I.W. Wainer , R. Moaddel
Due to the lack of sensitivity in current methods for the determination of fenoterol (Fen), a rapid LC–MS/MS method was developed for the determination of (R,R′)-Fen and (R,R′;S,S′)-Fen in plasma and urine. The method was fully validated and was linear from 50pg/ml to 2000pg/ml for plasma and from 2.500ng/ml to 160ng/ml for urine with a lower limit of quantitation of 52.8pg/ml in plasma. The coefficient of variation was <15% for the high QC standards and <10% for the low QC standards in plasma and was <15% for the high and low QC standards in urine. The relative concentrations of (R,R′)-Fen and (S,S′)-Fen were determined using a chirobiotic T chiral stationary phase. The method was used to determine the concentration of (R,R′)-Fen in plasma and urine samples obtained in an oral cross-over study of (R,R′)-Fen and (R,R′;S,S′)-Fen formulations. The results demonstrated a potential pre-systemic enantioselective interaction in which the (S,S′)-Fen reduces the sulfation of the active (R,R′)-Fen. The data suggest that a non-racemic mixture of the Fen enantiomers may provide better bioavailability of the active (R,R′)-Fen for use in the treatment of cardiovascular disease.
Source:Journal of Chromatography B, Volume 933
Author(s): M. Sanghvi , A. Ramamoorthy , J. Strait , I.W. Wainer , R. Moaddel
Due to the lack of sensitivity in current methods for the determination of fenoterol (Fen), a rapid LC–MS/MS method was developed for the determination of (R,R′)-Fen and (R,R′;S,S′)-Fen in plasma and urine. The method was fully validated and was linear from 50pg/ml to 2000pg/ml for plasma and from 2.500ng/ml to 160ng/ml for urine with a lower limit of quantitation of 52.8pg/ml in plasma. The coefficient of variation was <15% for the high QC standards and <10% for the low QC standards in plasma and was <15% for the high and low QC standards in urine. The relative concentrations of (R,R′)-Fen and (S,S′)-Fen were determined using a chirobiotic T chiral stationary phase. The method was used to determine the concentration of (R,R′)-Fen in plasma and urine samples obtained in an oral cross-over study of (R,R′)-Fen and (R,R′;S,S′)-Fen formulations. The results demonstrated a potential pre-systemic enantioselective interaction in which the (S,S′)-Fen reduces the sulfation of the active (R,R′)-Fen. The data suggest that a non-racemic mixture of the Fen enantiomers may provide better bioavailability of the active (R,R′)-Fen for use in the treatment of cardiovascular disease.
17 July 2013,
15:23:06
Publication date: 1 August
2013
Source:Journal of Chromatography B, Volume 932
Author(s): Mariam Srour , Issam Kassab , Hiam Matta , Assem Elkak
Waldenstrom's macroglobulinemia (WM) is considered by the Revised European American Lymphoma (REAL) and World Health Organization (WHO) as a clinical lympho plasmacytic syndrome associated with high monoclonal (IgM) secretion. The hyper viscosity syndrome is associated with several clinical disorders of monoclonal IgM. Patients with clinical symptoms of hyper viscosity should be treated with plasma pheresis, which is limited by its non-selective removal of all plasma components. These limitations have steered efforts to find a more specific removal according to clinical needs and avoiding plasma components replacement. Removal by specific adsorption is the most powerful selective apheresis technique. The active adsorbed ligand is covalently bound to an insoluble matrix through which plasma is passed. Amino acids have been introduced as ligands in clinical apheresis for the removal of auto antibodies associated with autoimmune diseases. The present preliminary study describes the binding of monoclonal IgM antibodies from sera of patients with WM, on histidine immobilized to activated sepharose. The advantages of efficient binding and elution, suggest histidine adsorbents as prospective clinical means suitable for the removal of monoclonal IgM from sera of patients diagnosed with WM. The advantages of efficient adsorption and elution, non toxicity of histidine, good selectivity, good stability, as well as their low cost strongly suggest histidine adsorbents as prospective clinical means suitable for the removal of monoclonal IgM from sera of patients diagnosed with WM.
Source:Journal of Chromatography B, Volume 932
Author(s): Mariam Srour , Issam Kassab , Hiam Matta , Assem Elkak
Waldenstrom's macroglobulinemia (WM) is considered by the Revised European American Lymphoma (REAL) and World Health Organization (WHO) as a clinical lympho plasmacytic syndrome associated with high monoclonal (IgM) secretion. The hyper viscosity syndrome is associated with several clinical disorders of monoclonal IgM. Patients with clinical symptoms of hyper viscosity should be treated with plasma pheresis, which is limited by its non-selective removal of all plasma components. These limitations have steered efforts to find a more specific removal according to clinical needs and avoiding plasma components replacement. Removal by specific adsorption is the most powerful selective apheresis technique. The active adsorbed ligand is covalently bound to an insoluble matrix through which plasma is passed. Amino acids have been introduced as ligands in clinical apheresis for the removal of auto antibodies associated with autoimmune diseases. The present preliminary study describes the binding of monoclonal IgM antibodies from sera of patients with WM, on histidine immobilized to activated sepharose. The advantages of efficient binding and elution, suggest histidine adsorbents as prospective clinical means suitable for the removal of monoclonal IgM from sera of patients diagnosed with WM. The advantages of efficient adsorption and elution, non toxicity of histidine, good selectivity, good stability, as well as their low cost strongly suggest histidine adsorbents as prospective clinical means suitable for the removal of monoclonal IgM from sera of patients diagnosed with WM.
Quantification of vitamin D and 25-hydroxyvitamin D in soft tissues by liquid chromatography–tandem mass spectrometry
17 July 2013,
15:23:06
Publication date: 1 August
2013
Source:Journal of Chromatography B, Volume 932
Author(s): Tristan E. Lipkie , Amber Janasch , Bruce R. Cooper , Emily E. Hohman , Connie M. Weaver , Mario G. Ferruzzi
Inadequate data on tissue distribution of vitamin D and its metabolites remains a barrier to defining health outcomes of vitamin D intake and 25-hydroxyvitamin D (25(OH)D) status. The purpose of this study was to develop a method for the analysis of vitamin D2 (ergocalciferol), vitamin D3 (cholecalciferol), 25(OH)D2, and 25(OH)D3 in soft tissues, and determine distribution in select tissues from a dose–response study of vitamin D2 and vitamin D3 in rats. Liver, gastrocnemius muscle, and epididymal fat homogenates were analyzed by liquid chromatography–tandem mass spectrometry (LC–MS/MS) with electrospray ionization following liquid–liquid extraction, solid-phase extraction, and derivatization with 4-phenyl-1,2,4-triazoline-3,5-dione (PTAD). A dose–response was observed in most tissues for vitamin D and 25(OH)D from both vitamers. Vitamin D concentration was greater in epididymal fat than gastrocnemius muscle and liver, but 25(OH)D concentration was not significantly different between tissues. Soft tissues of rats fed crystalline vitamin D3 had higher concentrations of total vitamin D than those of rats fed yeast-derived vitamin D2, while total 25(OH)D concentrations were similar between vitamin D sources. This method is well suited to more complete studies of vitamin D bioavailability and metabolite tissue distribution.
Source:Journal of Chromatography B, Volume 932
Author(s): Tristan E. Lipkie , Amber Janasch , Bruce R. Cooper , Emily E. Hohman , Connie M. Weaver , Mario G. Ferruzzi
Inadequate data on tissue distribution of vitamin D and its metabolites remains a barrier to defining health outcomes of vitamin D intake and 25-hydroxyvitamin D (25(OH)D) status. The purpose of this study was to develop a method for the analysis of vitamin D2 (ergocalciferol), vitamin D3 (cholecalciferol), 25(OH)D2, and 25(OH)D3 in soft tissues, and determine distribution in select tissues from a dose–response study of vitamin D2 and vitamin D3 in rats. Liver, gastrocnemius muscle, and epididymal fat homogenates were analyzed by liquid chromatography–tandem mass spectrometry (LC–MS/MS) with electrospray ionization following liquid–liquid extraction, solid-phase extraction, and derivatization with 4-phenyl-1,2,4-triazoline-3,5-dione (PTAD). A dose–response was observed in most tissues for vitamin D and 25(OH)D from both vitamers. Vitamin D concentration was greater in epididymal fat than gastrocnemius muscle and liver, but 25(OH)D concentration was not significantly different between tissues. Soft tissues of rats fed crystalline vitamin D3 had higher concentrations of total vitamin D than those of rats fed yeast-derived vitamin D2, while total 25(OH)D concentrations were similar between vitamin D sources. This method is well suited to more complete studies of vitamin D bioavailability and metabolite tissue distribution.
Measurement of free carnitine and acylcarnitines in plasma by HILIC-ESI-MS/MS without derivatization
17 July 2013,
15:23:06
Publication date: 1 August
2013
Source:Journal of Chromatography B, Volume 932
Author(s): Minzhi Peng , Li Liu , Minyan Jiang , Cuili Liang , Xiaoyuan Zhao , Yanna Cai , Huiying Sheng , Zhiying Ou , Hong Luo
Measurement of carnitine and acylcarnitines in plasma is important in diagnosis of fatty acid β-oxidation disorders and organic acidemia. The usual method uses flow injection tandem mass spectrometry (FIA-MS/MS), which has limitations. A rapid and more accurate method was developed to be used for high-risk screening and diagnosis. Carnitine and acylcarnitines were separated by hydrophilic interaction liquid chromatography (HILIC) without derivatization and detected with a QTRAP MS/MS System. Total analysis time was 9.0min. The imprecision of within- and between-run were less than 6% and 17%, respectively. Recoveries were in the range of 85–110% at three concentrations. Some acylcarnitine isomers could be separated, such as dicarboxylic and hydroxyl acylcarnitines. The method could also separate interferent to avoid false positive results. 216 normal samples and 116 patient samples were detected with the validated method, and 49 patients were identified with fatty acid oxidation disorders or organic acidemias.
Source:Journal of Chromatography B, Volume 932
Author(s): Minzhi Peng , Li Liu , Minyan Jiang , Cuili Liang , Xiaoyuan Zhao , Yanna Cai , Huiying Sheng , Zhiying Ou , Hong Luo
Measurement of carnitine and acylcarnitines in plasma is important in diagnosis of fatty acid β-oxidation disorders and organic acidemia. The usual method uses flow injection tandem mass spectrometry (FIA-MS/MS), which has limitations. A rapid and more accurate method was developed to be used for high-risk screening and diagnosis. Carnitine and acylcarnitines were separated by hydrophilic interaction liquid chromatography (HILIC) without derivatization and detected with a QTRAP MS/MS System. Total analysis time was 9.0min. The imprecision of within- and between-run were less than 6% and 17%, respectively. Recoveries were in the range of 85–110% at three concentrations. Some acylcarnitine isomers could be separated, such as dicarboxylic and hydroxyl acylcarnitines. The method could also separate interferent to avoid false positive results. 216 normal samples and 116 patient samples were detected with the validated method, and 49 patients were identified with fatty acid oxidation disorders or organic acidemias.
Analysis of tyrosinase binders from Glycyrrhiza uralensis root: Evaluation and comparison of tyrosinase immobilized magnetic fishing-HPLC and reverse ultrafiltration-HPLC
17 July 2013,
15:23:06
Publication date: 1 August
2013
Source:Journal of Chromatography B, Volume 932
Author(s): Liangliang Liu , Shuyun Shi , Xiaoqing Chen , Mijun Peng
Tyrosinase inhibitors play an important role in cosmetic products, food supplements and medicinal industries. In this study, a new facile method based on tyrosinase immobilized magnetic fishing (IMF) coupled with high performance liquid chromatography–diode array detector–tandem mass spectrometry (HPLC–DAD–MS/MS) was developed to screen and identify tyrosinase binders from Glycyrrhiza uralensis root. Experiments were carried out to select optimal immobilization and incubation conditions. The activity of immobilized tyrosinase retained 76.3% after ten consecutive cycles, and remained over 95% when stored at 4°C for about two months. Eleven tyrosinase binders, including original compounds and transformation products were successfully screened and characterized from G. uralensis root, while dihydrodaidzein and pratensein were reported for the first time. Compared with ultrafiltration-HPLC assay, IMF-HPLC displayed many attractive advantages, including convenient solid–liquid separation ability, good stability, high reusability and activity, which indicated that IMF-HPLC had a broad applicability. The results indicated that IMF-HPLC method is a facile, effective and reproductive way to screen and identify active components from complex mixtures.
Source:Journal of Chromatography B, Volume 932
Author(s): Liangliang Liu , Shuyun Shi , Xiaoqing Chen , Mijun Peng
Tyrosinase inhibitors play an important role in cosmetic products, food supplements and medicinal industries. In this study, a new facile method based on tyrosinase immobilized magnetic fishing (IMF) coupled with high performance liquid chromatography–diode array detector–tandem mass spectrometry (HPLC–DAD–MS/MS) was developed to screen and identify tyrosinase binders from Glycyrrhiza uralensis root. Experiments were carried out to select optimal immobilization and incubation conditions. The activity of immobilized tyrosinase retained 76.3% after ten consecutive cycles, and remained over 95% when stored at 4°C for about two months. Eleven tyrosinase binders, including original compounds and transformation products were successfully screened and characterized from G. uralensis root, while dihydrodaidzein and pratensein were reported for the first time. Compared with ultrafiltration-HPLC assay, IMF-HPLC displayed many attractive advantages, including convenient solid–liquid separation ability, good stability, high reusability and activity, which indicated that IMF-HPLC had a broad applicability. The results indicated that IMF-HPLC method is a facile, effective and reproductive way to screen and identify active components from complex mixtures.
Development of achiral and chiral 2D HPLC methods for analysis of albendazole metabolites in microsomal fractions using multivariate analysis for the in vitro metabolism
17 July 2013,
15:23:06
Publication date: 1 August
2013
Source:Journal of Chromatography B, Volume 932
Author(s): Kátia Roberta A. Belaz , Edenir Rodrigues Pereira-Filho , Regina V. Oliveira
In this work, the development of two multidimensional liquid chromatography methods coupled to a fluorescence detector is described for direct analysis of microsomal fractions obtained from rat livers. The chiral multidimensional method was then applied for the optimization of the in vitro metabolism of albendazole by experimental design. Albendazole was selected as a model drug because of its anthelmintics properties and recent potential for cancer treatment. The development of two fully automated achiral–chiral and chiral–chiral high performance liquid chromatography (HPLC) methods for the determination of albendazole (ABZ) and its metabolites albendazole sulphoxide (ABZ-SO), albendazole sulphone (ABZ-SO2) and albendazole 2-aminosulphone (ABZ-SO2NH2) in microsomal fractions are described. These methods involve the use of a phenyl (RAM-phenyl-BSA) or octyl (RAM-C8-BSA) restricted access media bovine serum albumin column for the sample clean-up, followed by an achiral phenyl column (15.0×0.46cmI.D.) or a chiral amylose tris(3,5-dimethylphenylcarbamate) column (15.0×0.46cmI.D.). The chiral 2D HPLC method was applied to the development of a compromise condition for the in vitro metabolism of ABZ by means of experimental design involving multivariate analysis.
Source:Journal of Chromatography B, Volume 932
Author(s): Kátia Roberta A. Belaz , Edenir Rodrigues Pereira-Filho , Regina V. Oliveira
In this work, the development of two multidimensional liquid chromatography methods coupled to a fluorescence detector is described for direct analysis of microsomal fractions obtained from rat livers. The chiral multidimensional method was then applied for the optimization of the in vitro metabolism of albendazole by experimental design. Albendazole was selected as a model drug because of its anthelmintics properties and recent potential for cancer treatment. The development of two fully automated achiral–chiral and chiral–chiral high performance liquid chromatography (HPLC) methods for the determination of albendazole (ABZ) and its metabolites albendazole sulphoxide (ABZ-SO), albendazole sulphone (ABZ-SO2) and albendazole 2-aminosulphone (ABZ-SO2NH2) in microsomal fractions are described. These methods involve the use of a phenyl (RAM-phenyl-BSA) or octyl (RAM-C8-BSA) restricted access media bovine serum albumin column for the sample clean-up, followed by an achiral phenyl column (15.0×0.46cmI.D.) or a chiral amylose tris(3,5-dimethylphenylcarbamate) column (15.0×0.46cmI.D.). The chiral 2D HPLC method was applied to the development of a compromise condition for the in vitro metabolism of ABZ by means of experimental design involving multivariate analysis.
LC–MS/MS determination of pramipexole on rat dried blood spots: A pharmacokinetic study
17 July 2013,
15:23:06
Publication date: 1 August
2013
Source:Journal of Chromatography B, Volume 932
Author(s): R. Nageswara Rao , B. Sravan , K. Ramakrishna , B. Raju , R. Srinivas
A simple and selective liquid chromatography–tandem mass spectrometric method for determination of pramipexole on rat dried blood spots was developed and validated. Chromatographic separation was achieved on a Synergy polar-RP column using 10mM ammonium acetate and methanol (50:50, v/v) as mobile phase in an isocratic mode of elution at a flow rate of 1.0mL/min. LC–MS was performed in a positive ion electro spray ionization mode and the MS/MS ion transitions 212.10→153.03 for PRX and 198.10→153.03 for internal standard (2-amino-4,5,6,7-tetrahydro-6-ethyl-amino-benzthiazole) were monitored. The developed method exhibited a linear dynamic range over 100–5000pg/mL for PRX on dried blood spots. The overall extraction recovery of PRX from DBS was 96.7%. The intra- and inter-day accuracy and precision were within the pre-defined limits of ≤15% at all concentrations. Influence of hematocrit and spot volume on dried blood spot was also evaluated and found to be well within the acceptable limits. The method was successfully applied to pharmacokinetic studies of PRX in rats.
Source:Journal of Chromatography B, Volume 932
Author(s): R. Nageswara Rao , B. Sravan , K. Ramakrishna , B. Raju , R. Srinivas
A simple and selective liquid chromatography–tandem mass spectrometric method for determination of pramipexole on rat dried blood spots was developed and validated. Chromatographic separation was achieved on a Synergy polar-RP column using 10mM ammonium acetate and methanol (50:50, v/v) as mobile phase in an isocratic mode of elution at a flow rate of 1.0mL/min. LC–MS was performed in a positive ion electro spray ionization mode and the MS/MS ion transitions 212.10→153.03 for PRX and 198.10→153.03 for internal standard (2-amino-4,5,6,7-tetrahydro-6-ethyl-amino-benzthiazole) were monitored. The developed method exhibited a linear dynamic range over 100–5000pg/mL for PRX on dried blood spots. The overall extraction recovery of PRX from DBS was 96.7%. The intra- and inter-day accuracy and precision were within the pre-defined limits of ≤15% at all concentrations. Influence of hematocrit and spot volume on dried blood spot was also evaluated and found to be well within the acceptable limits. The method was successfully applied to pharmacokinetic studies of PRX in rats.
A rapid and sensitive assay to quantify valproyl 1-O-acyl glucuronide in supernatants of sandwich-cultured rat hepatocytes using ultra-high performance liquid chromatography–tandem mass spectrometry
17 July 2013,
15:23:06
Publication date: 1 August
2013
Source:Journal of Chromatography B, Volume 932
Author(s): Jayakumar Surendradoss , András Szeitz , Xiao Wei Teng , Thomas K.H. Chang , Frank S. Abbott
A rapid and sensitive ultra-high performance liquid chromatography–tandem mass spectrometry (UHPLC–MS/MS) method was developed and validated for the determination of valproyl-1-O-acyl glucuronide (VPA-G) levels in hepatocyte culture medium. Chromatographic separation was achieved using a Waters Acquity UPLC® BEH C18 column (1.7μm, 2.1mm×50mm) with gradient elution and a total run time of 4min. [2H6]-VPA-G was used as internal standard (IS). Quantification was performed in the multiple reaction monitoring (MRM) mode using the total ion current of the MRM transition pairs m/z 319.1→142.7 and m/z 319.1→175.2 for VPA-G, and m/z 325.1→149.3 and m/z 325.1→174.9 for the IS under negative electrospray ionization mode. The assay was linear over the VPA-G concentrations of 0.5–500ng/mL, with a r 2 value of 0.995±0.002 (mean±SD). The intra- and inter-day accuracy (% deviation) ranged from −10.2% to 11.1%, whereas the intra- and inter-day precision (% RSD) were ≤7.43%. The method was applied successfully to the quantification of VPA-G levels in culture supernatants of sandwich-cultured rat hepatocytes treated with valproic acid (VPA). No significant difference in the levels of VPA-G over a culture period of 6 days was observed in an experiment that investigated the effect of the age of hepatocyte culture on the extent of VPA glucuronidation. The method presented here for the direct quantification of VPA-G is an improvement of existing methods in the literature and offers a shorter run time and greater sensitivity that enables the use of small volumes of sample. To the best of our knowledge, this is the first validated UHPLC–MS/MS method applied to the quantification of VPA-G in cell culture supernatants.
Source:Journal of Chromatography B, Volume 932
Author(s): Jayakumar Surendradoss , András Szeitz , Xiao Wei Teng , Thomas K.H. Chang , Frank S. Abbott
A rapid and sensitive ultra-high performance liquid chromatography–tandem mass spectrometry (UHPLC–MS/MS) method was developed and validated for the determination of valproyl-1-O-acyl glucuronide (VPA-G) levels in hepatocyte culture medium. Chromatographic separation was achieved using a Waters Acquity UPLC® BEH C18 column (1.7μm, 2.1mm×50mm) with gradient elution and a total run time of 4min. [2H6]-VPA-G was used as internal standard (IS). Quantification was performed in the multiple reaction monitoring (MRM) mode using the total ion current of the MRM transition pairs m/z 319.1→142.7 and m/z 319.1→175.2 for VPA-G, and m/z 325.1→149.3 and m/z 325.1→174.9 for the IS under negative electrospray ionization mode. The assay was linear over the VPA-G concentrations of 0.5–500ng/mL, with a r 2 value of 0.995±0.002 (mean±SD). The intra- and inter-day accuracy (% deviation) ranged from −10.2% to 11.1%, whereas the intra- and inter-day precision (% RSD) were ≤7.43%. The method was applied successfully to the quantification of VPA-G levels in culture supernatants of sandwich-cultured rat hepatocytes treated with valproic acid (VPA). No significant difference in the levels of VPA-G over a culture period of 6 days was observed in an experiment that investigated the effect of the age of hepatocyte culture on the extent of VPA glucuronidation. The method presented here for the direct quantification of VPA-G is an improvement of existing methods in the literature and offers a shorter run time and greater sensitivity that enables the use of small volumes of sample. To the best of our knowledge, this is the first validated UHPLC–MS/MS method applied to the quantification of VPA-G in cell culture supernatants.
No comments:
Post a Comment