13 results match your criteria Chinese Journal Of Analytical Chemistry[Journal]

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Emission of M2X+ cluster ions in thermal ionization mass spectrometry in the presence of graphite.

Fresenius J Anal Chem 2001 Dec;371(8):1098-103

Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining, China.

The emission of M2X+ cluster ions in thermal ionization mass spectrometry when graphite is loaded on the heating filaments was studied. The emission model of non-reductive thermal ionization of graphite was preliminarily discussed and factors influencing the thermal emission of M2X+ ions were investigated. The results show that the intensities of M2X+ cluster ions are related to ionic radius and crystal lattice energy, and possibly also to the solvation energies of ions. Read More

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http://dx.doi.org/10.1007/s002160101086DOI Listing
December 2001

A novel water-soluble fluorescent probe for the determination of methylamine.

Authors:
H Gu H M Ma S C Liang

Fresenius J Anal Chem 2001 Oct;371(4):570-3

Center for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing.

A novel water-soluble fluorescent probe, monosodium 7-(4,6-dichloro-1,3,5-triazinylamino)-1,3-naphthalenedisulfonic acid (DTND), was synthesized by reacting cyanuric chloride with 7-amino-1,3-naphthalenedisulfonic acid monopotassium salt at 0-5 degrees C. This new reagent was used for the determination of methylamine. The linear range is 3x10(-6)-2x10(-4) mol L(-1) with a detection limit (S/N=3) of 7. Read More

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http://dx.doi.org/10.1007/s002160101034DOI Listing
October 2001
1 Read

Sol-gel-derived carbon ceramic electrode containing 9,10-phenanthrenequinone, and its electrocatalytic activity toward iodate.

Fresenius J Anal Chem 2001 Oct;371(3):337-41

Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, People's Republic of China.

9,10-Phenanthrenequinone (PQ) supported on graphite powder by adsorption was dispersed in propyltrimethoxysilane-derived gels to yield a conductive composite which was used as electrode material to fabricate a PQ-modified carbon ceramic electrode. In this configuration, PQ acts as a catalyst, graphite powder guarantees conductivity by percolation, the silicate provides a rigid porous backbone, and the propyl groups endow hydrophobicity and thus limit the wetting region of the modified electrode. Square-wave voltammetry was exploited to investigate the pH-dependent electrochemical behavior of the composite electrode and an almost Nernstian response was obtained from pH 0. Read More

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http://dx.doi.org/10.1007/s002160100950DOI Listing
October 2001
3 Reads

Resolution of the essential constituents of Ramulus cinnamomi by an evolving chemometric approach.

Fresenius J Anal Chem 2001 Oct;371(3):331-6

College of Chemistry and Chemical Engineering, Research Center for Modernization of Chinese Herbal Medicine, Central South University, Changsha, PR China.

The analysis of complex mixtures, such as those of traditional Chinese medicine (TCM), is difficult by conventional methods of analysis. Chemometric methods provide a new way to solve such problems. Subwindow factor analysis (SFA) paired with the evolving window orthogonal projection (EWOP) method, has been used as a new evolving approach to the resolution of volatile components of Ramulus cinnamomi (RC). Read More

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http://dx.doi.org/10.1007/s002160100977DOI Listing
October 2001
1 Read

Chips and Qi: microcomponent-based analysis in traditional Chinese medicine.

Fresenius J Anal Chem 2001 Sep;371(2):190-4

Department of Chemical Engineering, Hong Kong University of Science and Technology, Kowloon, SAR, China.

Over the last 50 years or so Traditional Chinese medicine (TCM) has been subject to intensive basic and clinical research. Although the effectiveness and remarkable safety of TCM have been documented after controlled clinical studies, there are several herbal and animal parts that are toxic or difficult to identify. DNA polymorphism-based assays have recently been developed for the identification of herbal medicines. Read More

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http://dx.doi.org/10.1007/s002160100964DOI Listing
September 2001
1 Read

Development and certification of a coal fly ash certified reference material for selected polycyclic aromatic hydrocarbons.

Authors:
X Cao X Xu W Cui Z Xi

Fresenius J Anal Chem 2001 Aug;370(8):1035-40

Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, PR China.

The development and certification of a coal fly ash certified reference material (CRM) for polycyclic aromatic hydrocarbons (PAH) is described; this is the first natural matrix CRM for organic environmental analysis in China. The homogeneity and stability of this material have been tested by HPLC. The concentrations of several PAH were determined by use of two independent, different methods--solvent extraction-HPLC analysis with UV detection coupled with fluorescence detection (FLD) and solvent extraction, isolation with a silica column, and GC analysis with flame ionization detection (FID). Read More

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August 2001
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A collision model for DNA separation by capillary electrophoresis in dilute polymer solution.

Fresenius J Anal Chem 2001 Aug;370(8):1015-22

Dalian Institute of Chemical Physics, Chinese Academy of Science.

A theoretical description, based on chemical kinetics and electrochemistry, is given of DNA separation in dilute polymer solution by capillary electrophoresis. A self-consistent model was developed leading to predictions of the DNA electrophoretic velocity as a function of the experimental conditions--polymer concentration, temperature, and electric field strength. The effect of selected experimental variables is discussed. Read More

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http://dx.doi.org/10.1007/s002160100902DOI Listing
August 2001
4 Reads

Arsenic speciation based on ion exchange high-performance liquid chromatography hyphenated with hydride generation atomic fluorescence and on-line UV photo oxidation.

Authors:
B He G B Jiang X Xu

Fresenius J Anal Chem 2000 Dec;368(8):803-8

Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing.

An on-line method capable of the separation of arsenic species was developed for the speciation of arsenite As(III), arsenate As(V), monomethylarsenic (MMA) and dimethylarsenic acid (DMA) in biological samples. The method is based on the combination of high-performance liquid chromatograph (HPLC) for separation, UV photo oxidation for sample digestion and hydride generation atomic fluorescence spectrometry (HGAFS) for sensitive detection. The best separation results were obtained with an anion-exchange AS11 column protected by an AG11 guard column, and gradient elution with NaH2PO4 and water as mobile phase. Read More

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December 2000
5 Reads

Determination of marker constituents in radix Glycyrrhizae and radix Notoginseng by near infrared spectroscopy.

Fresenius J Anal Chem 2000 Jul;367(5):491-6

Department of Pharmaceutics, Human Medical University, Changsha, PR China.

High-performance liquid chromatographic (HPLC) methods were developed for the determination of glycyrrhizin in radix Glycyrrhizae and ginsenosides Rb1, Rb2, Rc, Rd, Re, Rf and Rg, in radix Notoginseng. These methods were used as reference methods for near-infrared (NIR) spectroscopy. Spectroscopic calibrations were developed for the determination of glycyrrhizin, the total content of ginsenosides and the individual major ginsenosides Rb1, Rd, Re and Rg1. Read More

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http://dx.doi.org/10.1007/s002160000356DOI Listing
July 2000
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River sediment (S-37)--a new analytical quality control material ensuring comparability of chlorinated hydrocarbon analysis during an international environmental study in China.

Fresenius J Anal Chem 2000 Jun;367(3):232-40

Joint Research Centre Ispra, Environment Institute, Italy.

A sediment reference material (S-37) was prepared as analytical quality control material to be used within an international project on polychlorinated hydrocarbon analysis in two Chinese rivers. The raw material was sampled during a cruise on Yangtse River and transported afterwards to the JRC Ispra for further processing. The material was treated according to the general principles applicable for candidate reference material production. Read More

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http://dx.doi.org/10.1007/s002160000335DOI Listing

Mercury determination with ICP-MS: signal suppression by acids.

Fresenius J Anal Chem 2000 Jan;366(1):48-53

Institute for Analytical Chemistry, Karl-Franzens-University Graz, Austria.

When mercury is quantified by ICP-MS under routine conditions (external calibration) in reference materials, which require mineralization with nitric acid, the experimental concentrations are almost always unacceptably low in comparison to certified values. Sorption of mercury on the Teflon surfaces of the digestion vessels, changes in the viscosity of the aspirated solutions, in the efficiency of the nebulization, in the aerosol transport, and memory effects cannot be responsible for the low results. The intensity of a mercury signal is strongly dependent on the concentration of nitric acid (and other mineral acids) in the measured solutions. Read More

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http://dx.doi.org/10.1007/s002160050010DOI Listing
January 2000
1 Read

Determination of lead in fine particulates by slurry sampling electrothermal atomic absorption spectrometry.

Authors:
J C Yu K F Ho S C Lee

Fresenius J Anal Chem 2001 Jan;369(2):170-5

Department of Chemistry, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong.

A simple method for determining lead in fine particulates (PM2.5) by using electrothermal atomic absorption spectrometry (ETAAS) has been developed. Particulates collected on Nuclepore filter by using a dichotomous sampler were suspended in diluted nitric acid after ultrasonic agitation. Read More

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http://dx.doi.org/10.1007/s002160000637DOI Listing
January 2001
3 Reads

Surface-renewable cobalt(II) hexacyanoferrate-modified graphite organosilicate electrode and its electrocatalytic oxidation of thiosulfate.

Authors:
P Wang Y Yuan G Zhu

Fresenius J Anal Chem 2001 Jan;369(2):153-8

Laboratory of Electroanalytical Chemistry and National Analytical Research Center of Electrochemistry and Spectroscopy, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, People's Republic of China.

Cobalt(II) hexacyanoferrate (CoHCF) was deposited on graphite powder by an in situ chemical deposition procedure and then dispersed into methyltrimethoxysilane-derived gels to prepare a surface-renewable CoHCF-modified electrode. The electrochemical behavior of the modified electrode in different supporting electrolyte solutions was characterized by cyclic voltammetry. In addition, square-wave voltammetry was employed to investigate the pNa-dependent electrochemical behavior of the electrode. Read More

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http://dx.doi.org/10.1007/s002160000635DOI Listing
January 2001
2 Reads
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