Analysis of Beta-blockers in Doping Control

A retiabte and sensitive method is developed for the detection of β-blockerswhich are excreted in free or conjugated forms in human urine.9 β-blockers werederivatized by MSTFA and MBTFA and subjected to GC/MSB analysis.Both chromato-grams and mass spectrometric data were obtained from full scanning mode.This methodis suitable for routine screening and confirmation of β-blockers in doping control.     

Advances of Chromatography in Analysis of Complex Samples

The separation and identification of complex samples is an urgent task that analytical chemistry has to face. Chromatography, as an important analysis technique, has been widely applied to many fields, such as life science, environment, medicine, food and petrochemical engineering.Recently, with the progress of science and tech-     

Analysis of two-phase flows in gas—solids injectors

The results of the numerical analysis of the aerodynamic model of gas-solid flow in injectors for both single-size particles and a mixture are presente The theoretical pressure distributions along the axis in the respective parts of the injector (nozzle, mixing tube, diffuser and pipe section) are foun to be in agreement with the experimental data of Bohnet and Wagenknecht and the data of Hutt at the assumed values of the energy transformation coefficients. Fitting the results to the data allowed one to find the values of angles of jet expansion in the hopper area.In the case of a mixed-size particle mixture it is found that the particle acceleration depends strongly on the inlet gas jet velocity and that the dif     

Analysis of Phthalate Esters in Air,Soil and Plants in Plastic Film Greenhouse

The phthalate esters such as MDP,DEP,BDP and DEHP in air,soil and plant smples in plastic film greenhouse were clean up with fine silica gel column and determined with HPLC.It was found that the concentrations of PEs in ari and soil samples in plastic film greenhouse are much higher than those of contrast samples. But concentration of PEs in plants in plastic film greenhouse are not remarkably affected by the pollution of air and soil.     

Analysis of Chlorogenic Acid in Herbal Medicines by Capillary Electrophoresis

Atpresent,thecommonlyusedmethodforanalyzingherbalmedicinesishighperformanceliquidchromatography(HPLC).However,theuseofHPLCisrestrictedformanyreasons.Themostseriousproblemisthatthechromatographiccolumniseasilycontaminated.ComparedwithHPLC,capillaryelectrophoresis(CE)ischaracterizedwithhighefficiency,rapidity,lowcostandmultiplemodestobechosen.Inaddition,thecapillarycanbeeasilyregenerated.SoCEisidealforanalyzing"dirty"samples,suchasChineseherbalmedicines.Infact,studiesintheareaarebecoming…     

Analysis of valence orbitals in the “core” regions

An analysis of the valence orbitais of a “frozen core” GVB wavefunction in the regions close to the nuclei has been performed for the ground state of the K₂ molecule. Possible simplifications in the use of the “frozen core” approach are suggested.     

Analysis of PAHs in air-borne particulates in Hong Kong City by heuristic evolving latent projections

Ｔｈｅａｎａｌｙｓｉｓｏｆｕｎｋｎｏｗｎｃｏｍｐｌｅｘｒｅａｌｓａｍｐｌｅｓ,ｓｕｃｈａｓｂｉｏｌｏｇｉｃａｌｐｒｏｄｕｃｔｓ,ｎａｔｕｒａｌｍｅｄｉｃｉｎｅｓ,ｅｎｖｉｒｏｎｍｅｎｔａｌｓａｍｐｌｅｓ,ｅｔｃ.,ｐｌａｙｓａｎｉｍｐｏｒｔａｎｔｒｏｌｅｉｎｂｉｏｃｈｅｍｉｓｔｒｙ,ｐｈａｒｍａｃｅｕｔｉｃａｌｃｈｅｍｉｓｔｒｙ,ｅｎｖｉｒｏｎｍｅｎｔａｌｃｈｅｍｉｓｔｒｙａｎｄｏｔｈｅｒｆｉｅｌｄｓ.Ｉｔｈａｓｂｅｃｏｍｅｏｎｅｏｆｔｈｅｈｏｔｓｐｏｔｓａｎｄｄｉｆｆｉｃｕｌｔｐｏｉｎｔｓｉｎｍｏｄｅ…     

Characters of the Plateau of Methanol Increment in Frontal Analysis in Reversed Phase Liquid Chromatography

With insulin methanol-water,and the ion-pairing agent,hydrochloric acid and trifluroacetic acid(TEA),the character of the first plateau(FP)on the elution curve of frontal analysis in reversed phase liquid chromatography(RPLC)was investigated by on-line UV-spectrometry and identified with nuclear magnetic resonance(NMR) spectrometry and mass spectrometry.The profile of the FP is the same as that of a usual elution curve of methanol in frontal analysis(FA).When the insulin concentration was limited to a certain range,the height of the FP was found to be proportional to the insulin concentration in mobile phase and its length companying to shorten,The FP profile on the intersection of two tangents reflects the components of the microstructure in the depth direction of the bonded stationary phase layer and the desorption dynamics of the displaced components.The displaced methanol was quantitatively determined by NMR and on-line UV spectrometries.TFA with high UV absorbance can not be used as an ionpairing agent for the investigation of the FP in RPLC,but if can be used as a good marker to investigate the complicated transfer process of components in the stationary phase in RPLC.A stoichiometric displacement process between solute and solvent was proved to be valid in both usual and FA in RPLC.From the point of view of dynamics of mass transfer, the solutes can only contact to the surface of stationary phase in usual RPLC,while solute can penetrate into it in FA of RPLC.The solvation of insulin in methanol and water solution as an example indicating the usage of the FP in the FA was also investigated in this paper.     

Preparation of Functional Magnetic Nanoparticles and its Application in Diagnostic Analysis

The magnetic nanoparticles modified with carboxyl functional group were synthesized and characterized. These nanoparticles covalently bound with hepatitis B surface antibody（HBsAb）, were used to detect hepatitis B surface antigen （HBsAg） in immunovoltammetry. The detection limit was found to be 0.06 ng/mL, which is much higher than that of enzyme-linked immunosorbent assay （ELISA） used in clinical analysis.     

Thermodynamic Analysis of Phase Equilibria in the System Cyclohexane—Methanol

The phase diagram of cyclohexane-methanol was thermodynamically modeledin the range of 150 T/K 360 and at a pressure of 1 bar on the basis ofavailable experimental data. The Gibbs energy functions of four pure solid andtwo mixture phases were taken into consideration. The liquid phase was describedby a model based on mole fraction statistics and the simplified assumption ofmethanol tetramers mixed with cyclohexane monomers. The gas phase was treatedas a nonideal mixture with a Gibbs energy modeled on the basis of the virialcoefficient formalism considering only monomers. The Gibbs energies of the twosolid modifications of pure methanol, as well as pure cyclohexane, were fixedusing literature data. The pressure dependence of the Gibbs energies of the liquidand solid phases were neglected. The complete T-x phase diagram includinggas/liquid equilibria as well as p-x phase diagrams in the range of 20 and 55°C werecalculated. Experimental and calculated data were found to agree reasonably well.     

Preparation of Luminol-doped Nanoparticle and Its Application in DNA Hybridization Analysis

Introduction The analysis of DNA sequence and DNA mutant detection play fundamental roles in the rapid development of molecular diagnostics and in the anticancer drug screening. Therefor many detection techniques of DNA sequence have been developed in recent years. These techniques mainly depend on the nucleic acid hybridization1 and their sensitivities are related to the specific activity of the label linked to the DNA probe. The degree of hybridization of probe to its complementary DN…     

Analysis of Ascorbic Acid in Single Human Neutrophils by Electrochemical Detection

Ascorbic acid in individual human neutrophils was determincd by capillary zone clectrophoresis with electrochemical detection. In order to overcome the influence of the adsorption of the substances in cells on the inner surface wall of the capillary on the migration time and the unmber of theorctical plates, a proccdure for treating capillaries has bccn described.     

SPE–GC–MS Analysis of Chloroform in Drinking Water

In this paper we report a method based on solid-phase extraction (SPE) and subsequent analysis by gas chromatography combined with mass spectrometry for determination of chloroform in potable water. The affinity of chloroform for the resin enables almost complete recovery of the analyte. The analytical method proposed enables evaluation of chloroform levels down to 0.295 g L^–1. The procedure is characterized by lack of interferences, in fact the GC–MS analysis reveals the presence of only one peak, that of chloroform. Use of CDCl₃ as labelled internal standard also makes the procedure suitable for use as a reference analytical method for quantification of chloroform in drinking water.     

Introducing Field Environmental–Analytical Chemistry in the Quantitative Analysis Laboratory

Advances in instrumentation and technology now provide the ability to perform many quantitative determinations in the field. Additionally, the potential for sample degradation and analyte decomposition make it necessary to determine certain analytes (e.g., dissolved oxygen) in the field when conducting environmental analyses. Unfortunately, field environmental—analytical chemistry is not a substantial portion of the analytical chemistry curriculum at many institutions. Students in lower-level analytical chemistry courses are often non-chemistry science majors, particularly at institutions with small chemistry departments. We report here on an experiment in which field environmental-analytical chemistry is introduced in the quantitative analysis laboratory. In the context of a water quality assessment of a local river, students determine temperature, pH, ORP, nitrate nitrogen, and ammonia nitrogen at several points in the river. The experimental objective is to determine the potential effects local agricultural practices and treated wastewater discharge may be having on the water composition. The pedagogical objective is to expose these students to the difficulties involved in making analytical determinations in unfamiliar and/or disruptive settings.     

GIS-based Analysis of Main Air Pollutants of Changchun City in Summer

To gain a better understanding of the characteristics of air pollution of Changchun city, P. R. China, in summer, the analytical methods of geographical information system（GIS） and statistical analysis software SPSS were applied to the analysis of the monitored concentrations of SO2 , NO2, and O3 in July of 2002 to 2004 in Changchun city. The results obtained show that the average hourly O3 concentrations in July 2002 and 2004 were higher than the firstlevel hourly standard of China. At the same time, the dynamic distribution of the 03 concentration and the relationship between the concentration of 03 and that of NOx were studied. The air quality evaluation result of Changchun city indicates that the southwest of this city was heavily polluted during the monitored period.     

Cellulose Solubility in Deep Eutectic Solvents: Inspecting Quantitative Hydrogen-Bonding Analysis

According to the Kamlet-Abraham-Taft(KAT) polarity parameters(α, β, π^*), polymers and solvents can be categorized as hydrogenbond(H-bond) acidic(α>β) or H-bond basic(α<β). Recently, we proposed a quantitative hydrogen bonding(QHB) analysis to predict the solubility of polymers in ionic liquids(ILs) using the product of ΔαΔβ<0 as an indicator, where Δα is the difference between the H-bond acidic parameters of the polymer and IL, and Δβ is the difference in their basicity, whil...     

Nutraceutical Products—State-of-the-Art for Sample Preparation in Pesticide Residues Analysis

Nutraceutical products are plant-based materials primarily valued for their possible medicinal or therapeutic properties. According to their “natural” origin they are often perceived as being safe; however, for the prevention of economic losses, pesticides may be used against pest, mold and insects causing plant damage. Bearing in mind that a nutraceutical is a concentrated form of the plant, pesticides could be found in the final product in possibly worrying concentration. Nutraceutical products and dried herb materials typically represent very complex matrices for pesticide residue analysis, therefore a proper sample preparation protocol with appropriate clean-up steps is necessary prior to the analysis. Hence, this article gives an overview of pesticide residue analyses in nutraceuticals and provides the state of the art for sample preparation techniques applied for different types of nutraceuticals.     

Quantitative Analysis of Busulfan in Human Plasma by LC-MS–MS

High-performance liquid chromatography with tandem mass spectrometry has been used for rapid, specific, and sensitive analysis of busulfan in human plasma. Busulfan-d₈ was used as internal standard. Analysis was performed on a C₁₈ column (50 mm × 2.1 mm, 3.5-µm particles) with water–methanol 80:20 (v/v) as mobile phase at a flow-rate of 0.30 mL min^?1. Detection was by tandem triple–quadrupole mass spectrometry with turbo ion-spray ionization. Linear calibration plots were obtained over the concentration range 1.096–1,096 ng mL^?1. The assay is ideally suited to monitoring of busulfan and determination of its pharmacokinetic data.