In this paper,we consider the maximal positive definite solution of the nonlinear matrix equation.By using the idea of Algorithm 2.1 in ZHANG(2013),a new inversion-free method with a stepsize parameter is proposed to ...In this paper,we consider the maximal positive definite solution of the nonlinear matrix equation.By using the idea of Algorithm 2.1 in ZHANG(2013),a new inversion-free method with a stepsize parameter is proposed to obtain the maximal positive definite solution of nonlinear matrix equation X+A^(*)X|^(-α)A=Q with the case 0<α≤1.Based on this method,a new iterative algorithm is developed,and its convergence proof is given.Finally,two numerical examples are provided to show the effectiveness of the proposed method.展开更多
In this paper,a novel method for investigating the particle-crushing behavior of breeding particles in a fusion blanket is proposed.The fractal theory and Weibull distribution are combined to establish a theoretical m...In this paper,a novel method for investigating the particle-crushing behavior of breeding particles in a fusion blanket is proposed.The fractal theory and Weibull distribution are combined to establish a theoretical model,and its validity was verified using a simple impact test.A crushable discrete element method(DEM)framework is built based on the previously established theoretical model.The tensile strength,which considers the fractal theory,size effect,and Weibull variation,was assigned to each generated particle.The assigned strength is then used for crush detection by comparing it with its maximum tensile stress.Mass conservation is ensured by inserting a series of sub-particles whose total mass was equal to the quality loss.Based on the crushable DEM framework,a numerical simulation of the crushing behavior of a pebble bed with hollow cylindrical geometry under a uniaxial compression test was performed.The results of this investigation showed that the particle withstands the external load by contact and sliding at the beginning of the compression process,and the results confirmed that crushing can be considered an important method of resisting the increasing external load.A relatively regular particle arrangement aids in resisting the load and reduces the occurrence of particle crushing.However,a limit exists to the promotion of resistance.When the strain increases beyond this limit,the distribution of the crushing position tends to be isotropic over the entire pebble bed.The theoretical model and crushable DEM framework provide a new method for exploring the pebble bed in a fusion reactor,considering particle crushing.展开更多
Effective partitioning is crucial for enabling parallel restoration of power systems after blackouts.This paper proposes a novel partitioning method based on deep reinforcement learning.First,the partitioning decision...Effective partitioning is crucial for enabling parallel restoration of power systems after blackouts.This paper proposes a novel partitioning method based on deep reinforcement learning.First,the partitioning decision process is formulated as a Markov decision process(MDP)model to maximize the modularity.Corresponding key partitioning constraints on parallel restoration are considered.Second,based on the partitioning objective and constraints,the reward function of the partitioning MDP model is set by adopting a relative deviation normalization scheme to reduce mutual interference between the reward and penalty in the reward function.The soft bonus scaling mechanism is introduced to mitigate overestimation caused by abrupt jumps in the reward.Then,the deep Q network method is applied to solve the partitioning MDP model and generate partitioning schemes.Two experience replay buffers are employed to speed up the training process of the method.Finally,case studies on the IEEE 39-bus test system demonstrate that the proposed method can generate a high-modularity partitioning result that meets all key partitioning constraints,thereby improving the parallelism and reliability of the restoration process.Moreover,simulation results demonstrate that an appropriate discount factor is crucial for ensuring both the convergence speed and the stability of the partitioning training.展开更多
The application of nitrogen fertilizers in agricultural fields can lead to the release of nitrogen-containing gases(NCGs),such as NO_(x),NH_(3) and N_(2)O,which can significantly impact regional atmospheric environmen...The application of nitrogen fertilizers in agricultural fields can lead to the release of nitrogen-containing gases(NCGs),such as NO_(x),NH_(3) and N_(2)O,which can significantly impact regional atmospheric environment and con-tribute to global climate change.However,there remain considerable research gaps in the accurate measurement of NCGs emissions from agricultural fields,hindering the development of effective emission reduction strategies.We improved an open-top dynamic chambers(OTDCs)system and evaluated the performance by comparing the measured and given fluxes of the NCGs.The results showed that the measured fluxes of NO,N_(2)O and NH_(3)were 1%,2%and 7%lower than the given fluxes,respectively.For the determination of NH_(3) concentration,we employed a stripping coil-ion chromatograph(SC-IC)analytical technique,which demonstrated an absorption efficiency for atmospheric NH_(3) exceeding 96.1%across sampling durations of 6 to 60 min.In the summer maize season,we utilized the OTDCs system to measure the exchange fluxes of NO,NH_(3),and N_(2)O from the soil in the North China Plain.Substantial emissions of NO,NH_(3) and N_(2)O were recorded following fertilization,with peaks of 107,309,1239 ng N/(m^(2)·s),respectively.Notably,significant NCGs emissions were observed following sus-tained heavy rainfall one month after fertilization,particularly with NH_(3) peak being 4.5 times higher than that observed immediately after fertilization.Our results demonstrate that the OTDCs system accurately reflects the emission characteristics of soil NCGs and meets the requirements for long-term and continuous flux observation.展开更多
Marine thin plates are susceptible to welding deformation owing to their low structural stiffness.Therefore,the efficient and accurate prediction of welding deformation is essential for improving welding quality.The t...Marine thin plates are susceptible to welding deformation owing to their low structural stiffness.Therefore,the efficient and accurate prediction of welding deformation is essential for improving welding quality.The traditional thermal elastic-plastic finite element method(TEP-FEM)can accurately predict welding deformation.However,its efficiency is low because of the complex nonlinear transient computation,making it difficult to meet the needs of rapid engineering evaluation.To address this challenge,this study proposes an efficient prediction method for welding deformation in marine thin plate butt welds.This method is based on the coupled temperature gradient-thermal strain method(TG-TSM)that integrates inherent strain theory with a shell element finite element model.The proposed method first extracts the distribution pattern and characteristic value of welding-induced inherent strain through TEP-FEM analysis.This strain is then converted into the equivalent thermal load applied to the shell element model for rapid computation.The proposed method-particularly,the gradual temperature gradient-thermal strain method(GTG-TSM)-achieved improved computational efficiency and consistent precision.Furthermore,the proposed method required much less computation time than the traditional TEP-FEM.Thus,this study lays the foundation for future prediction of welding deformation in more complex marine thin plates.展开更多
At present,there is currently a lack of unified standard methods for the determination of antimony content in groundwater in China.The precision and trueness of related detection technologies have not yet been systema...At present,there is currently a lack of unified standard methods for the determination of antimony content in groundwater in China.The precision and trueness of related detection technologies have not yet been systematically and quantitatively evaluated,which limits the effective implementation of environmental monitoring.In response to this key technical gap,this study aimed to establish a standardized method for determining antimony in groundwater using Hydride Generation–Atomic Fluorescence Spectrometry(HG-AFS).Ten laboratories participated in inter-laboratory collaborative tests,and the statistical analysis of the test data was carried out in strict accordance with the technical specifications of GB/T 6379.2—2004 and GB/T 6379.4—2006.The consistency and outliers of the data were tested by Mandel's h and k statistics,the Grubbs test and the Cochran test,and the outliers were removed to optimize the data,thereby significantly improving the reliability and accuracy.Based on the optimized data,parameters such as the repeatability limit(r),reproducibility limit(R),and method bias value(δ)were determined,and the trueness of the method was statistically evaluated.At the same time,precision-function relationships were established,and all results met the requirements.The results show that the lower the antimony content,the lower the repeatability limit(r)and reproducibility limit(R),indicating that the measurement error mainly originates from the detection limit of the method and instrument sensitivity.Therefore,improving the instrument sensitivity and reducing the detection limit are the keys to controlling the analytical error and improving precision.This study provides reliable data support and a solid technical foundation for the establishment and evaluation of standardized methods for the determination of antimony content in groundwater.展开更多
Aim A reliable and rapid HPLC method was developed for quantitative determination of coniferyl femlate, an ester of ferulic acid, with multiple pharmacological activities in Angelica sinensis and Ligusticum chuanxiong...Aim A reliable and rapid HPLC method was developed for quantitative determination of coniferyl femlate, an ester of ferulic acid, with multiple pharmacological activities in Angelica sinensis and Ligusticum chuanxiong, two commonly used Chinese medicines. Methods The determination was achieved by using a Zorbax ODS C18 analytical column （250 mm×4.6 mm ID, 5 μm） at isocratic elution of 1% aqueous acetic acid and acetonitrile （1：1） with diode-array detection （318 nm）. The calibration curve of coniferyl femlate showed good linearity （r^2 = 0.9995） within the test range. Results The developed method showed good precision with intra- and inter-day variations of 0.22% - 1.16% and 0.86% - 2.62% between the levels of 0.380 - 0.038 mg·mL^-1, respectively. The repeatability represented as RSD of coniferyl femlate was less than 2.7% for three levels （0.2 - 1.0 g of Angelica sinensis）, and the recovery was 105.3% with RSD of 3.2%. Conclusion The validated method was successfully applied to quantify coniferyl femlate in 12 samples of Danggui and Chuanxiong.展开更多
A reliable and validated HPLC method was established for the assay of trypsin inhibitors（TI）and it was used in the investigation of the active TI components inMomordica cochinchinensis（Cucurbitaceae family）.The un...A reliable and validated HPLC method was established for the assay of trypsin inhibitors（TI）and it was used in the investigation of the active TI components inMomordica cochinchinensis（Cucurbitaceae family）.The underlying principle of the assay is the measurement of the decrease in trypsin activity due to the presence of TI in analyzed samples,which was achieved by using HPLC separation and quantification of p-nitroanilide that was generated by tryptic hydrolysis of N-α-benzoyl-DL-arginine -4-nitroanilide.The results showed that the HPLC method had higher selectivity than conventional spectrophotometric assay.展开更多
[Objective] This study aimed to optimize the chromatographic conditions for detecting ellagic acid in pomegranate peels using HPLC method. [Method] By using 0.2 mg/ml ellagic acid standard solution, on the basis of si...[Objective] This study aimed to optimize the chromatographic conditions for detecting ellagic acid in pomegranate peels using HPLC method. [Method] By using 0.2 mg/ml ellagic acid standard solution, on the basis of single-factor experiment and orthogonal experiment, chromatographic conditions （mobile phase ratio, flow rate, col- umn temperature） for detecting ellagic acid using HPLC were optimized. Based on the optimal chromatographic conditions, the ellagic acid content in experimental pomegranate peels was determined. [Resull] The optimal chromatographic conditions for detecting ellagic acid in pomegranate peels using HPLC method are： 1.2% phos- phoric acid：acetonitrile=85：15, column temperature of 35 ℃, and flow rate of 1.0 ml/min. The linear regression equation of ellagic acid is： y=2.9e＋0.6x＋4.4e＋5 （FF=9 999）. Ac- cording to the standard addition recovery test, the average recovery rate of ellagic acid is 98.20%, and RSD is 0.60%. Under above optimized chromatographic condi- tions, ellagic acid can be well separated from other interfering components in pomegranate peels, with shorter peak time and ideal effect, which is convenient for the detection in production practices. [Conclusion] This study laid the foundation for detecting ellagic acid in pomegranate peels using HPLC method.展开更多
A sensitive RP-HPLC-UV method has been developed and validated for the quantification of daphnoretin in rat plasma. Daphnoretin was extracted from rat plasma by protein precipitation and liquid-liquid extraction. Sepa...A sensitive RP-HPLC-UV method has been developed and validated for the quantification of daphnoretin in rat plasma. Daphnoretin was extracted from rat plasma by protein precipitation and liquid-liquid extraction. Separation was performed on a Diamonsil C18 column （200 mm× 4.6 mm, 5 μm） with a mobile phase of methanol-20 mmol/L ammonium acetate （adjusted to pH 3.2 with acetic acid, 42：58, v/v） at a flow rate of 1.0 mL/min. The UV detector was set at 345 nm and column temperature was set at 40 ℃. The calibration curves were linear over the concentration range of 0.020-2.00 ~tg/mL, The lower limit of quantification （LLOQ） of daphnoretin in rat plasma was 0.020 μg/mL. The intra- and inter-day relative standard deviation （RSD） for measurement of quality control （QC） samples （0.050, 0.200 and 1.60 μg/mL） ranged from 5.0%-10.6%. Relative error （RE） was from ±（1.2%-2.5%）. The validated method was used successfully in a pharmacokinetic study of daphnoretin in rats after intraperitoneal injection.展开更多
A sensitive and specific high performance liquid chromatography method was established for measuring cefazolin sodium level in rabbit synovial fluid. Acetonitrile was used to precipitate proteins and antipyrine was us...A sensitive and specific high performance liquid chromatography method was established for measuring cefazolin sodium level in rabbit synovial fluid. Acetonitrile was used to precipitate proteins and antipyrine was used as internal standard. Samples were analyzed on a Dionex Ultimate U3000 HPLC system equipped with Phenomenex Luna C18 column （150 mmx4.60 mm, 5 Bm, 100 A）. The mobile phase consisted of acetonitrile and 0.1% formic acid in water. The flow rate was 1 mL/min. The detection wavelength was set at 272 nm. The column temperature was maintained at 25 ℃. The calibration curve was linear in the range of 1.0-100.0 μg/mL （r2 = 0.9999）. The limit of detection （LOD, S/N - 3） was 0.07 μg/mL. The limit of quantitation （LOD, S/N = 10） was 0.22 pg/mL. The recovery of cefazolin sodium （low, medium and high） was 124.6%, 117.8%, and 100.6% （RSD% - 1.9%, 4.0%, 1.1%, n = 5）, respectively. The intra-day and inter-day precision values were in the range of 0.5%-2.7%. The method was simple, sensitive and reliable. It can be used for the quantitative determination of cefazolin sodium in rabbit synovial fluid.展开更多
A rapid, accurate and sensitive HPLC method for the determination of bupropion hydrochloride in a new tablet formulation is described. Chromatographic separation of bupropion hydrochloride is achieved using a mobile p...A rapid, accurate and sensitive HPLC method for the determination of bupropion hydrochloride in a new tablet formulation is described. Chromatographic separation of bupropion hydrochloride is achieved using a mobile phase consisting of methanol -0.01 mol·L -1 ammonium dihydrogen phosphate (80:20, v/v, pH 4.8) at a flow rate of 1.0 mL·min -1 on a Hypersil BDS C18 column. Absorbance is monitored at 251 nm where bupropion hydrochloride has maximum absorption in the mobile phase. The linear range of determination for bupropion hydrochloride is between 2.12 and 21.2 μg·mL -1. The proposed method was validated with respect to accuracy, precision, limits of detection and quantification and robustness, etc.展开更多
A pre-column derivatization HPLC method for the determination of peimine(P)and peiminine(PE)in Bulbus Fritillariae has been developed. Under the derivatization conditions optimized,the calibration curve is Y1=-3.83...A pre-column derivatization HPLC method for the determination of peimine(P)and peiminine(PE)in Bulbus Fritillariae has been developed. Under the derivatization conditions optimized,the calibration curve is Y1=-3.83×103+1.33 ×105X1,r=0.998 for P and Y2=-7.86 × 102+6.33 × 104X2,r=0995 for PE,where Y is the peak area and X is the weight of the alkaloid; the average recovery is 98.0%(n=5, RSD=2.1%) for P and 101.0%(n=5,RSD=4.1%)for PE,the linear range is from 0.504 μg to 3.126μg for P and from 0.520μgto 3.328μgfor PE,respectively. Results of the determination of the two alkaloids in several samples of different Fritillaria species from various parts ofthe country are presented.The results suggest that P and PE are two major chemical constituents in bulbs of different Fritillaria species,and that the method developed is generally appli-cable to the determination of the hydroxy group on aliphatic fused ring systems without steric hin-drance.展开更多
[Objective] This study aimed to establish a method for determining the content of Astragaloside IV in Yupingfeng oral solution.[Method] The HPLC-ELSD method was adopted.The chromatographic column was Venusil MP（4.6 m...[Objective] This study aimed to establish a method for determining the content of Astragaloside IV in Yupingfeng oral solution.[Method] The HPLC-ELSD method was adopted.The chromatographic column was Venusil MP（4.6 mm × 150 mm,5 μm）.The mobile phase was acetonitrile-water（35∶65）.The ELSD evaporator tube temperature was 65 ℃.N2 was used as the carrier gas（pressure,30 psi）.[Result] When the content of Astragaloside IV ranged from 0.5 to 5.0 μg,the Astragaloside IV content showed a good linear relationship with peak area（r=0.999,n=6）.The average recovery was 96.36%,and the RSD was 2.46%.[Conclusion] This method is accurate and reliable,and can be applied in the quality control of Yupingfeng oral solution.展开更多
基金Supported in part by Natural Science Foundation of Guangxi(2023GXNSFAA026246)in part by the Central Government's Guide to Local Science and Technology Development Fund(GuikeZY23055044)in part by the National Natural Science Foundation of China(62363003)。
文摘In this paper,we consider the maximal positive definite solution of the nonlinear matrix equation.By using the idea of Algorithm 2.1 in ZHANG(2013),a new inversion-free method with a stepsize parameter is proposed to obtain the maximal positive definite solution of nonlinear matrix equation X+A^(*)X|^(-α)A=Q with the case 0<α≤1.Based on this method,a new iterative algorithm is developed,and its convergence proof is given.Finally,two numerical examples are provided to show the effectiveness of the proposed method.
基金supported by Anhui Provincial Natural Science Foundation(2408085QA030)Natural Science Research Project of Anhui Educational Committee,China(2022AH050825)+3 种基金Medical Special Cultivation Project of Anhui University of Science and Technology(YZ2023H2C008)the Excellent Research and Innovation Team of Anhui Province,China(2022AH010052)the Scientific Research Foundation for High-level Talents of Anhui University of Science and Technology,China(2021yjrc51)Collaborative Innovation Program of Hefei Science Center,CAS,China(2019HSC-CIP006).
文摘In this paper,a novel method for investigating the particle-crushing behavior of breeding particles in a fusion blanket is proposed.The fractal theory and Weibull distribution are combined to establish a theoretical model,and its validity was verified using a simple impact test.A crushable discrete element method(DEM)framework is built based on the previously established theoretical model.The tensile strength,which considers the fractal theory,size effect,and Weibull variation,was assigned to each generated particle.The assigned strength is then used for crush detection by comparing it with its maximum tensile stress.Mass conservation is ensured by inserting a series of sub-particles whose total mass was equal to the quality loss.Based on the crushable DEM framework,a numerical simulation of the crushing behavior of a pebble bed with hollow cylindrical geometry under a uniaxial compression test was performed.The results of this investigation showed that the particle withstands the external load by contact and sliding at the beginning of the compression process,and the results confirmed that crushing can be considered an important method of resisting the increasing external load.A relatively regular particle arrangement aids in resisting the load and reduces the occurrence of particle crushing.However,a limit exists to the promotion of resistance.When the strain increases beyond this limit,the distribution of the crushing position tends to be isotropic over the entire pebble bed.The theoretical model and crushable DEM framework provide a new method for exploring the pebble bed in a fusion reactor,considering particle crushing.
基金funded by the Beijing Engineering Research Center of Electric Rail Transportation.
文摘Effective partitioning is crucial for enabling parallel restoration of power systems after blackouts.This paper proposes a novel partitioning method based on deep reinforcement learning.First,the partitioning decision process is formulated as a Markov decision process(MDP)model to maximize the modularity.Corresponding key partitioning constraints on parallel restoration are considered.Second,based on the partitioning objective and constraints,the reward function of the partitioning MDP model is set by adopting a relative deviation normalization scheme to reduce mutual interference between the reward and penalty in the reward function.The soft bonus scaling mechanism is introduced to mitigate overestimation caused by abrupt jumps in the reward.Then,the deep Q network method is applied to solve the partitioning MDP model and generate partitioning schemes.Two experience replay buffers are employed to speed up the training process of the method.Finally,case studies on the IEEE 39-bus test system demonstrate that the proposed method can generate a high-modularity partitioning result that meets all key partitioning constraints,thereby improving the parallelism and reliability of the restoration process.Moreover,simulation results demonstrate that an appropriate discount factor is crucial for ensuring both the convergence speed and the stability of the partitioning training.
基金supported by the National Key Research and Develop-ment Program(No.2022YFC3701103)the National Natural Science Foundation of China(Nos.42130714 and 41931287).
文摘The application of nitrogen fertilizers in agricultural fields can lead to the release of nitrogen-containing gases(NCGs),such as NO_(x),NH_(3) and N_(2)O,which can significantly impact regional atmospheric environment and con-tribute to global climate change.However,there remain considerable research gaps in the accurate measurement of NCGs emissions from agricultural fields,hindering the development of effective emission reduction strategies.We improved an open-top dynamic chambers(OTDCs)system and evaluated the performance by comparing the measured and given fluxes of the NCGs.The results showed that the measured fluxes of NO,N_(2)O and NH_(3)were 1%,2%and 7%lower than the given fluxes,respectively.For the determination of NH_(3) concentration,we employed a stripping coil-ion chromatograph(SC-IC)analytical technique,which demonstrated an absorption efficiency for atmospheric NH_(3) exceeding 96.1%across sampling durations of 6 to 60 min.In the summer maize season,we utilized the OTDCs system to measure the exchange fluxes of NO,NH_(3),and N_(2)O from the soil in the North China Plain.Substantial emissions of NO,NH_(3) and N_(2)O were recorded following fertilization,with peaks of 107,309,1239 ng N/(m^(2)·s),respectively.Notably,significant NCGs emissions were observed following sus-tained heavy rainfall one month after fertilization,particularly with NH_(3) peak being 4.5 times higher than that observed immediately after fertilization.Our results demonstrate that the OTDCs system accurately reflects the emission characteristics of soil NCGs and meets the requirements for long-term and continuous flux observation.
基金Supported by the National Natural Science Foundation of China under Grant No.51975138the High-Tech Ship Scientific Research Project from the Ministry of Industry and Information Technology under Grant No.CJ05N20the National Defense Basic Research Project under Grant No.JCKY2023604C006.
文摘Marine thin plates are susceptible to welding deformation owing to their low structural stiffness.Therefore,the efficient and accurate prediction of welding deformation is essential for improving welding quality.The traditional thermal elastic-plastic finite element method(TEP-FEM)can accurately predict welding deformation.However,its efficiency is low because of the complex nonlinear transient computation,making it difficult to meet the needs of rapid engineering evaluation.To address this challenge,this study proposes an efficient prediction method for welding deformation in marine thin plate butt welds.This method is based on the coupled temperature gradient-thermal strain method(TG-TSM)that integrates inherent strain theory with a shell element finite element model.The proposed method first extracts the distribution pattern and characteristic value of welding-induced inherent strain through TEP-FEM analysis.This strain is then converted into the equivalent thermal load applied to the shell element model for rapid computation.The proposed method-particularly,the gradual temperature gradient-thermal strain method(GTG-TSM)-achieved improved computational efficiency and consistent precision.Furthermore,the proposed method required much less computation time than the traditional TEP-FEM.Thus,this study lays the foundation for future prediction of welding deformation in more complex marine thin plates.
基金supported by the National Natural Science Foundation of China(Project No.42307555).
文摘At present,there is currently a lack of unified standard methods for the determination of antimony content in groundwater in China.The precision and trueness of related detection technologies have not yet been systematically and quantitatively evaluated,which limits the effective implementation of environmental monitoring.In response to this key technical gap,this study aimed to establish a standardized method for determining antimony in groundwater using Hydride Generation–Atomic Fluorescence Spectrometry(HG-AFS).Ten laboratories participated in inter-laboratory collaborative tests,and the statistical analysis of the test data was carried out in strict accordance with the technical specifications of GB/T 6379.2—2004 and GB/T 6379.4—2006.The consistency and outliers of the data were tested by Mandel's h and k statistics,the Grubbs test and the Cochran test,and the outliers were removed to optimize the data,thereby significantly improving the reliability and accuracy.Based on the optimized data,parameters such as the repeatability limit(r),reproducibility limit(R),and method bias value(δ)were determined,and the trueness of the method was statistically evaluated.At the same time,precision-function relationships were established,and all results met the requirements.The results show that the lower the antimony content,the lower the repeatability limit(r)and reproducibility limit(R),indicating that the measurement error mainly originates from the detection limit of the method and instrument sensitivity.Therefore,improving the instrument sensitivity and reducing the detection limit are the keys to controlling the analytical error and improving precision.This study provides reliable data support and a solid technical foundation for the establishment and evaluation of standardized methods for the determination of antimony content in groundwater.
基金Macao Science and Technology Development Fund(049/2005/A-R1) Jiangsu Key Laboratory for TCM FormulaeResearch, Nanjing University of Traditional Chinese Medicine (No.022021014003).
文摘Aim A reliable and rapid HPLC method was developed for quantitative determination of coniferyl femlate, an ester of ferulic acid, with multiple pharmacological activities in Angelica sinensis and Ligusticum chuanxiong, two commonly used Chinese medicines. Methods The determination was achieved by using a Zorbax ODS C18 analytical column （250 mm×4.6 mm ID, 5 μm） at isocratic elution of 1% aqueous acetic acid and acetonitrile （1：1） with diode-array detection （318 nm）. The calibration curve of coniferyl femlate showed good linearity （r^2 = 0.9995） within the test range. Results The developed method showed good precision with intra- and inter-day variations of 0.22% - 1.16% and 0.86% - 2.62% between the levels of 0.380 - 0.038 mg·mL^-1, respectively. The repeatability represented as RSD of coniferyl femlate was less than 2.7% for three levels （0.2 - 1.0 g of Angelica sinensis）, and the recovery was 105.3% with RSD of 3.2%. Conclusion The validated method was successfully applied to quantify coniferyl femlate in 12 samples of Danggui and Chuanxiong.
基金National Natural Science Foundation of China (Grant No 30873405)National Drug Innovation Program(Grant No.2009ZX09301-011)
文摘A reliable and validated HPLC method was established for the assay of trypsin inhibitors（TI）and it was used in the investigation of the active TI components inMomordica cochinchinensis（Cucurbitaceae family）.The underlying principle of the assay is the measurement of the decrease in trypsin activity due to the presence of TI in analyzed samples,which was achieved by using HPLC separation and quantification of p-nitroanilide that was generated by tryptic hydrolysis of N-α-benzoyl-DL-arginine -4-nitroanilide.The results showed that the HPLC method had higher selectivity than conventional spectrophotometric assay.
文摘[Objective] This study aimed to optimize the chromatographic conditions for detecting ellagic acid in pomegranate peels using HPLC method. [Method] By using 0.2 mg/ml ellagic acid standard solution, on the basis of single-factor experiment and orthogonal experiment, chromatographic conditions （mobile phase ratio, flow rate, col- umn temperature） for detecting ellagic acid using HPLC were optimized. Based on the optimal chromatographic conditions, the ellagic acid content in experimental pomegranate peels was determined. [Resull] The optimal chromatographic conditions for detecting ellagic acid in pomegranate peels using HPLC method are： 1.2% phos- phoric acid：acetonitrile=85：15, column temperature of 35 ℃, and flow rate of 1.0 ml/min. The linear regression equation of ellagic acid is： y=2.9e＋0.6x＋4.4e＋5 （FF=9 999）. Ac- cording to the standard addition recovery test, the average recovery rate of ellagic acid is 98.20%, and RSD is 0.60%. Under above optimized chromatographic condi- tions, ellagic acid can be well separated from other interfering components in pomegranate peels, with shorter peak time and ideal effect, which is convenient for the detection in production practices. [Conclusion] This study laid the foundation for detecting ellagic acid in pomegranate peels using HPLC method.
基金National Key Scientific Project for New Drug Discovery and Development(Grant No.2009ZX09301-012)
文摘A sensitive RP-HPLC-UV method has been developed and validated for the quantification of daphnoretin in rat plasma. Daphnoretin was extracted from rat plasma by protein precipitation and liquid-liquid extraction. Separation was performed on a Diamonsil C18 column （200 mm× 4.6 mm, 5 μm） with a mobile phase of methanol-20 mmol/L ammonium acetate （adjusted to pH 3.2 with acetic acid, 42：58, v/v） at a flow rate of 1.0 mL/min. The UV detector was set at 345 nm and column temperature was set at 40 ℃. The calibration curves were linear over the concentration range of 0.020-2.00 ~tg/mL, The lower limit of quantification （LLOQ） of daphnoretin in rat plasma was 0.020 μg/mL. The intra- and inter-day relative standard deviation （RSD） for measurement of quality control （QC） samples （0.050, 0.200 and 1.60 μg/mL） ranged from 5.0%-10.6%. Relative error （RE） was from ±（1.2%-2.5%）. The validated method was used successfully in a pharmacokinetic study of daphnoretin in rats after intraperitoneal injection.
基金National Natural Science Foundation(Grant No.81373372)Specialized Research Fund for the Doctoral Program of Higher Education of China(Grant No.20110001110021 and 20130001110059)
文摘A sensitive and specific high performance liquid chromatography method was established for measuring cefazolin sodium level in rabbit synovial fluid. Acetonitrile was used to precipitate proteins and antipyrine was used as internal standard. Samples were analyzed on a Dionex Ultimate U3000 HPLC system equipped with Phenomenex Luna C18 column （150 mmx4.60 mm, 5 Bm, 100 A）. The mobile phase consisted of acetonitrile and 0.1% formic acid in water. The flow rate was 1 mL/min. The detection wavelength was set at 272 nm. The column temperature was maintained at 25 ℃. The calibration curve was linear in the range of 1.0-100.0 μg/mL （r2 = 0.9999）. The limit of detection （LOD, S/N - 3） was 0.07 μg/mL. The limit of quantitation （LOD, S/N = 10） was 0.22 pg/mL. The recovery of cefazolin sodium （low, medium and high） was 124.6%, 117.8%, and 100.6% （RSD% - 1.9%, 4.0%, 1.1%, n = 5）, respectively. The intra-day and inter-day precision values were in the range of 0.5%-2.7%. The method was simple, sensitive and reliable. It can be used for the quantitative determination of cefazolin sodium in rabbit synovial fluid.
文摘A rapid, accurate and sensitive HPLC method for the determination of bupropion hydrochloride in a new tablet formulation is described. Chromatographic separation of bupropion hydrochloride is achieved using a mobile phase consisting of methanol -0.01 mol·L -1 ammonium dihydrogen phosphate (80:20, v/v, pH 4.8) at a flow rate of 1.0 mL·min -1 on a Hypersil BDS C18 column. Absorbance is monitored at 251 nm where bupropion hydrochloride has maximum absorption in the mobile phase. The linear range of determination for bupropion hydrochloride is between 2.12 and 21.2 μg·mL -1. The proposed method was validated with respect to accuracy, precision, limits of detection and quantification and robustness, etc.
文摘A pre-column derivatization HPLC method for the determination of peimine(P)and peiminine(PE)in Bulbus Fritillariae has been developed. Under the derivatization conditions optimized,the calibration curve is Y1=-3.83×103+1.33 ×105X1,r=0.998 for P and Y2=-7.86 × 102+6.33 × 104X2,r=0995 for PE,where Y is the peak area and X is the weight of the alkaloid; the average recovery is 98.0%(n=5, RSD=2.1%) for P and 101.0%(n=5,RSD=4.1%)for PE,the linear range is from 0.504 μg to 3.126μg for P and from 0.520μgto 3.328μgfor PE,respectively. Results of the determination of the two alkaloids in several samples of different Fritillaria species from various parts ofthe country are presented.The results suggest that P and PE are two major chemical constituents in bulbs of different Fritillaria species,and that the method developed is generally appli-cable to the determination of the hydroxy group on aliphatic fused ring systems without steric hin-drance.
基金Supported by General Program of Science and Technology Plan of Beijing Municipal Commission of Educational(KM201410020007)~~
文摘[Objective] This study aimed to establish a method for determining the content of Astragaloside IV in Yupingfeng oral solution.[Method] The HPLC-ELSD method was adopted.The chromatographic column was Venusil MP（4.6 mm × 150 mm,5 μm）.The mobile phase was acetonitrile-water（35∶65）.The ELSD evaporator tube temperature was 65 ℃.N2 was used as the carrier gas（pressure,30 psi）.[Result] When the content of Astragaloside IV ranged from 0.5 to 5.0 μg,the Astragaloside IV content showed a good linear relationship with peak area（r=0.999,n=6）.The average recovery was 96.36%,and the RSD was 2.46%.[Conclusion] This method is accurate and reliable,and can be applied in the quality control of Yupingfeng oral solution.
