Biomedical subjects

Junde Wang

Publications and source records attributed to Junde Wang.

16 recordsLinked to original sources

PubMed2006

Mass transfer kinetics and breakthrough and elution curves for bovine serum albumin using cibacron blue cellulose membranes.

The mass transfer of bovine serum albumin onto a stack of cibacron blue cellulose membranes in the loading and elution stages were studied. The breakthrough curves obtained in the loading stage were fitted to the pore and the lumped kinetic (LK) models, respectively. Then experimental data obtained in the elution stage were described by using the LK model in which the kinetic equation, the initial and the boundary conditions were rewritten according to the operation. For the breakthrough curves it was found that the contribution of the sorption kinetics to band broadening was significant whereas that of axial dispersion was negligible. In contrast, both of these contributions were significant to the profile of the elution curve. By studying the mass transfer kinetics in the elution stage, information about the influence of the module geometry on the performance of affinity membrane separations may be obtained.

Cellulose↗

PubMed2006

[Analysis of the impurity of bacterium source of standard endotoxin by gas chromatography/mass spectrometry].

To analyse the impurity of bacterium source of standard endotoxin, 3-hydroxy fatty acid species in different endotoxin standards was determined by gas chromatography/mass spectrometry (GC/MS) using N, O-bis (trimethylsilyl) trifluoroacetamide as the silanizing reagent. GC/MS analysis was performed using a gas chromatograph equipped with a 60 m x 0.25 mm i. d. DB-5 fused silica capillary column and an injector at 250 degrees C. Helium was used as the carrier gas under a constant pressure of 206 kPa. The oven was programmed at a rate of 5 degrees C /min from 90 degrees C (held for 5 min) to 280 degrees C (held for 5 min). The sample size was 1 microL. The transfer line was kept at 280 degrees C. The quadrupole mass spectrometer was operated in electron impact (EI) ionization mode, and the temperature of the source was kept at 250 degrees C. The kind of 3-hydroxy fatty acids in 9 000 EU/tube national standard endotoxin, 20 EU/tube working standard endotoxin, Escherichia coli, Pseudomonas aeruginosa and deionized water were determined to study the purity of bacterium source of the standard endotoxin. It was shown that 9 000 EU/tube endotoxin standard and Escherichia coli only contained 3-hydroxytetradecanoic acid. There was 3-hydroxydodecanoic acid in 20 EU/tube working standard endotoxin, which indicated the presence of impurity of bacterium source.

Bacteria↗

PubMed2006

[Direct enantioseparation of pantoprazole sodium by high performance liquid chromatography on teicoplanin-bonded chiral stationary phase].

Teicoplanin-bonded chiral stationary phase was prepared and used for the direct chiral separation of racemic pantoprazole sodium by reversed-phase high performance liquid chromatography (HPLC). The influences of organic modifiers, the composition of mobile phase, the flow rate and column temperature on enantioseparation were studied. It was found that methanol was preferred than acetonitrile when used as organic modifier. With the increase of column temperature, chiral solutes were less retained and the separation factor value decreased indicating that lower temperature was better for the enantioseparation. Better resolution was obtained at lower flow rates as a result of minimization of the resistance of mass transfer. Based on these experimental data, the chiral HPLC method for the analysis of pantoprazole sodium on prepared chiral column (150 mm x 4.6 mm i. d., 5 microm) was established with simplicity and good reproducibility, by using methanol-water (35 : 65, v/v) as mobile phase at a flow rate of 0.6 mL/min and 20 degrees C.

2-Pyridinylmethylsulfinylbenzimidazoles↗

PubMed2005

Evaluation of nonlinear chromatographic performance by frontal analysis using a simple multi-plate mathematical model.

A multi-plate (MP) mathematical model was proposed by frontal analysis to evaluate nonlinear chromatographic performance. One of its advantages is that the parameters may be easily calculated from experimental data. Moreover, there is a good correlation between it and the equilibrium-dispersive (E-D) or Thomas models. This shows that it can well accommodate both types of band broadening that is comprised of either diffusion-dominated processes or kinetic sorption processes. The MP model can well describe experimental breakthrough curves that were obtained from membrane affinity chromatography and column reversed-phase liquid chromatography. Furthermore, the coefficients of mass transfer may be calculated according to the relationship between the MP model and the E-D or Thomas models.

Chromatography↗

PubMed2005

Path concentration distribution of toluene using remote sensing FTIR and one-dimensional reconstruction method.

A one-dimensional mapping technique coupled with Open-Path remote sensing FTIR was presented in this article. This technique was applied to one of the air toxic volatile organic compounds (VOCs)-toluene. The Path Integrated Concentrations (PICs) of toluene in different path lengths along one beam path were fitted by polynomial fitting method with degrees from 3 to 7. The 6th degree polynomial fitting showed the best fitting result. Moreover, the methods of reconstructing path concentration distribution along the beam path by applying a Gaussian model and the derivative of 6th degree polynomial fitting function were established in this article. The reconstructed concentrations of toluene along the beam path by the two methods were experimentally close. Results showed that the concentration peaks were at 1.05 and 2.40 m from the instrument by applying the Gaussian model with the maximum concentration of 0.85 and 3.19 ppm, and at 0.99 and 2.49 m from the instrument with the maximum concentration of 0.78 and 2.80 ppm by applying the 6th polynomial fitting function. It was obvious that the reconstruction results by these two methods were very close. This approach could be appreciated for its fast calculation, exact peak location orientation and concentration flow tendency mapping. In can be concluded that this method can provide the path concentration distributions of much more releasing gases in a briefly and intuitionistic way. The remote sensing FTIR coupled with these mathematical reconstruction techniques can be applied to the real world environmental and industrial hygiene monitoring, thus works as an alert system for the VOCs pollution.

Air Pollutants↗

PubMed2005

Reconstruction of air contaminant concentration distribution in a two-dimensional plane by computed tomography and remote sensing FTIR spectroscopy.

This research combined open path FTIR (OP-FTIR) technique and computed tomography (CT) to reconstruct air contaminant concentration distribution in a two-dimensional plane. Remote sensing FTIR instrument was used to scan radial beam geometry and obtain path integrated concentration (PIC) data of acetone gas in the measuring plane. Smooth basis function minimization (SBFM) algorithm was adopted to reconstruct gaseous concentration distribution. For the purpose of finding out the preferable number of Gaussians used in SBFM algorithm, single-Gaussian, double-Gaussian, and three-Gaussian models were used respectively. Experimental results showed that the reconstruction result of acetone concentration distribution by SBFM algorithm with double-Gaussian model agreed with real distribution more qualitatively and quantitatively than single-Gaussian and three-Gaussian. Also, it has been proved that simulated annealing algorithm used in the optimization process of SBFM reconstruction was feasible and effective. Although computed tomography and remote sensing FTIR technique (CT-RS-FTIR) is still at the laboratory study stage, with further improvement of SBFM algorithm and beam geometry, it promises to be used in air pollution monitoring widely.

Acetone↗

PubMed2005

Orthogonal signal correction used for noise elimination of open path Fourier transform infrared spectra.

Open path Fourier transform infrared (OP-FTIR) spectroscopy is qualified in detecting mixtures by multivariate calibration methods such as partial least squares (PLS); however, its applications are still restricted by background noise, which is unavoidable for OP-FTIR spectra and cannot be resolved solely by multivariate calibration methods. Hence OP-FTIR spectra are often pretreated before the data are subjected to the multivariate calibration model. A new preprocessing technique, orthogonal signal correction (OSC), was presented in this paper. The principle of OSC is to remove the part in X orthogonal to Y, and it is implemented based on PLS and nonlinear iterative partial least squares (NIPALS) algorithm. The approach was applied to three different data sets of PLS model. It performed much better than classical PLS when handling data with noise but comparably when processing on the simulated data. Moreover, OSC could reduce the complexity of model, which would facilitate the interpretation of the models. The results reveal that the proposed method gives much better prediction than the classical PLS and is very promising for the wide use of OP-FTIR. The preprocessing technique, auto-scaling, and second-order derivatives (SOD) were also considered.

Air Pollutants↗

PubMed2005

Chiral speciation and determination of DL-selenomethionine enantiomers on a novel chiral ligand-exchange stationary phase.

A new type of chiral ligand-exchange stationary phase (CLES) was successfully synthesized by treating silica gel with beta-(3,4-epoxycyclohexyl)ethyltrimethoxy silane and opening the epoxy ring by L-isoleucine. The chiral speciation of DL-selenomethionine (DL-SeMet) by high-performance liquid chromatography (HPLC) with UV absorbance on the CLES column was studied. The influences of the contents of copper ion and methanol as well as the pH value in the mobile phase and temperature of the column on the efficiency of resolution of DL-SeMet were investigated in detail. DL-SeMet could be completely resolved within 40 min under the optimal operating conditions of 0.1 mmol/L Cu2+ at 0.05 mol/L KH2PO4 buffer (pH = 5.5) and 35 degrees C temperature of the column. The limits of detection of D- and L-SeMet were 255 ppb and 286 ppb, respectively. This method was applied to determine the D- and L-enantiomers of DL-SeMet in real samples, such as selenized yeast powder and garlic.

Chromatography, High Pressure Liquid↗

PubMed2005

[Study of enantiomeric separation of DL-amino acids on L-isoleucine-type chiral-ligand-exchange stationary phase].

Some underivatized DL-amino acid enantiomers were separated on L-isoleucine-type chiral-ligand-exchange stationary phase (EILE). The effects of contents of copper ion and methanol in mobile phase, temperature of column and flow rate of eluent on the efficiency and resolution of DL-amino acids were investigated in detail. The results showed that Cu(II) ion played an important role in the separation. When there was no Cu(II) ion in mobile phase, the DL-amino acids could not be enantio-separated, while the content of Cu(II) increased from 0.3 mmol/L to 1.2 mmol/L, the efficiency of resolution and retention time decreased. The increases of the content of methanol and column temperature are in favor of the resolution for most of DL-amino acids. The flow rate also affected the resolution results. Good results could be obtained in reducing flow rate but it prolongs the retention time. The mechanisms of different chiral separation results on the new stationary phase under different conditions were also investigated.

Chromatography, High Pressure Liquid↗

PubMed2004

Using genetic algorithm to identify completely unknown system in FTIR spectra analysis.

The article mainly focuses on how to identify completely unknown systems in FTIR spectra analysis by Genetic Algorithm (GA). The technique of multiplespot crossover combined with quantitative and adaptive mutation is used and the whole process is controlled by the fitness value and probability of selection in GA. A standard pure FTIR spectra database containing 101 air toxic organic compounds is set up. Six unknown samples are identified and quantitatively analyzed. The results indicate that GA can successfully identify even a perplexing sample containing 18 components. The concentration of each component in the samples can be determined at the same time. The maximal relative error is no more than 10%. It means that GA has the capability of simultaneous identification and prediction, especially for those completely unknown mixed spectra in FTIR.

Algorithms↗

PubMed2004

[Chiral separation of beta-receptor blockers and analogs on novel norvancomycin-bonded chiral stationary phase].

Enantiomeric separation of racemates of 8 beta-receptor blockers and analogs was performed on a novel norvancomycin-bonded chiral stationary phase (NVC-CSP) in polar organic mode using high performance liquid chromatography. The influences of mobile phase composition, acetic acid and triethylamine contents, temperature and flow rate on enantiomeric separation were studied. It was found experimentally that with the increase of the fraction of methanol in the mobile phase, the same tendency was found for all the chiral solutes studied, i. e., the decrease in retention factor (kappa) and the increase in the enantioselectivity factor (alpha). With the increase of column temperature, most solutes were less retained and the alpha value decreased accordingly. Better resolutions were obtained at lower flow rates as a result of the minimization of the resistance to mass-transfer. Better separation results and suitable retentions for most solutes were obtained when a mixture of acetonitrile-methanol-acetic acid-triethylamine (60: 40: 0.4: 0.2, v/v) was used as mobile phase at a flow rate of 0.6 mL/min, and the column temperature was set at 25 degrees C. Conclusions can be drawn from the experimental data that pi-pi complexation, dipole-stacking interactions were engaged in the process of enantiomeric separation, while hydrogen bonding interaction between solutes and CSP was commonly non-enantioselective, although it was mainly responsible for the increased retention in the acetonitrile-predominant mobile phases.

Adrenergic beta-Agonists↗

PubMed2004

[Direct enantiomeric separation of pantoprazole sodium by high performance liquid chromatography].

By using the Kromasil CHI-TBB chiral stationary phase, the racemic mixture of pantoprazole sodium was resolved in the normal phase mode. The influences of the composition of the mobile phase, the content of acidic and basic additives and the flow rate on this enantiomer separation were studied. The chiral high performance liquid chromatographic method for the analysis of pantoprazole sodium was established with high efficiency and good repeatability, by using hexane-isopropanol-acetic acid mixture (95:5:0.1, v/v) as the mobile phase at a flow rate of 2.0 mL/min at 25 degrees C.

2-Propanol↗

PubMed2003

Membrane cartridges for endotoxin removal from interferon preparations.

The suitability of membrane cartridges for the removal of endotoxin from both distilled water and interferon preparations was examined. The endotoxin concentrations were reduced to 4.0 and 7.3 EU/ml, respectively, when about 4000 ml of distilled water with 20 and 28 EU/ml were passed through the deoxycholate and chitosan immobilized membrane cartridges. When 200 ml of interferon preparation with endotoxin concentration more than 80 EU/ml and pH 3.9 were applied to a deoxycholate immobilized membrane cartridge at a flow-rate of 9 ml/min, the endotoxin concentration was reduced to less than 10 EU/ml. However, if an interferon preparation of 450 ml, with more than 80 EU/ml of endotoxin and pH 3.9 was applied to the chitosan immobilized membrane cartridge at a flow-rate of 18 ml/min, the endotoxin concentration was reduced to less than 10 EU/ml.

Adsorption↗

PubMed2003

Mapping air contaminant concentrations using remote sensing FTIR.

Spatial Mapping of air contaminant concentrations on a two-dimensional plane in outdoor air using remote sensing FTIR was conducted in this study. The quasitime-stationary experiment was carried out after chloroform and methanol dispersed 200 min later freely. The Path-Integrated Concentrations (PIC) in different optical path directions were obtained simultaneously. The kriged maps as well as the two-dimensional contour maps from PIC data of chloroform and methanol were plotted and compared. There was a consistency between the concentration peak positions in the two graphs. Although the concentrations were low as a whole, the kriged map of chloroform had a sharper peak than that of the methanol. It can be concluded from the experiment that mapping contaminant concentrations could help understand the peak locations of industrial emissions and provide improved estimates of pollutant flow and distribution. This study had the guiding significance in environmental monitoring and protection.

Air Pollutants↗

PubMed2003

A new type of chemically bonded phase for reversed-phase HPLC.

A new type of ether-bonded packing for reversed-phase HPLC (RP-HPLC) was synthesized by reacting 1-octanol with beta-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, followed by coupling the product onto porous silica. The prepared packing was characterized by elemental analysis, solid-state 13C NMR, and Fourier transform infrared (FT-IR) spectroscopy. Chromatographic evaluations were performed by using a mixture of organic compounds as the analyte and methanol-water as binary mobile phase. The influence of the composition of organic modifier on the retention behavior of basic compounds was studied. The hydrolytic stability of the packing between pH 2.5-7.5 was also investigated. The results showed that the new stationary phase has excellent chromatographic properties and good hydrolytic stability.

Journal Article↗

PubMed2002

A simple preparation of stationary phase of alkylamide reversed-phase liquid chromatograph for the separation of basic substances.

A simple preparation process of alkylamide phase for reversed-phase HPLC (RP-HPLC) is described. The process includes aminopropyltrimethoxysilane firstly reacted with octanoyl chloride, then the intermediate was coupled onto porous silica. The resultant bonded silica has a reproducible ligand surface concentration and homogenous bonded ligand distribution on the porous silica. Characterization of prepared packing was carried out with elemental analysis, solid-state 13C NMR and Fourier transform infrared (FT-IR). Chromatographic evaluations were carried out by using a mixture of organic compounds including acidic, basic and neutral analytes under methanol/water as binary mobile phase. The results showed that the stationary phase have excellent chromatographic properties and can be efficiently used for the separation of basic compounds.

Amides↗