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Results 301 - 350 of 1625
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Angood K M - - 2008
Organic and conventional lamb loin chops, labelled as British lamb, were bought from three major UK supermarket chains (designated A, B and C) in the Bristol area on 10 occasions over a six week period. Samples (n=360) were from unknown production systems but representative of what is available to UK ...
Sekiyama Yasuyo - - 2007
Novel technologies for measuring biological systems and methods for visualizing data have led to a revolution in the life sciences. Nuclear magnetic resonance (NMR) techniques can provide information on metabolite structure and metabolic dynamics at the atomic level. We have been developing a new method for measuring the dynamic metabolic ...
Nozawa Yuriko - - 2007
For the chemotaxonomic classification of actinomycetes, we developed a new method for the detection of the 2, 6-diaminopimelic acid (A(2)pm) stereoisomers and 3-hydroxy diaminopimelic acid (3-OH A(2)pm) in the cell wall peptidoglycan of actinomycetes using "the advanced Marfey's method", which consists of a chromatographic technique for the separation of amino ...
Ogretir C - - 2007
The geometries of 12 multi-halogenated pyridine derivatives were optimized using theoretical methods. The Hartree-Fock (HF) method with the 6-31G(d) and B3LYP method with 6-31G(d) basis sets were found to be adequate in calculation of absolute acidity constants, pK(a) values. A perfect correlation between the computed and experimentally obtained acidity constants, ...
Duangrat Chadarat - - 2007
The aim of this research was to develop and validate a spectrofluorimetric method for determination of tranexamic acid in hydrogel patch formulations. Tranexamic acid (trans-4-aminomethylcyclohexanecarboxylic acid, trans-AMCHA) is an antifibrinolytic drug that recently gained attention as a skin-whitening agent due to its inhibitory effect on ultraviolet (UV)-induced pigmentation in vivo. ...
Godin Jean-Philippe - - 2007
We describe a new method of assessing, in a single run, (13)C isotopic enrichment of both Val and Thr by gas chromatography-combustion-isotope-ratio mass spectrometry (GC-C-IRMS). This method characterised by a rapid one-step derivatisation procedure performed at room temperature to form the N(O,S)-ethoxycarbonyl ethyl ester derivatives, and a polar column for ...
Liu Boshu - - 2007
Protein SUMO modification is an important post-translational modification and the optimization of prediction methods remains a challenge. Here, by using Support Vector Machines algorithm (SVM), a novel computational method was developed for SUMO modification site prediction based on Sequential Forward Selection (SFS) of hundreds of amino acid properties, which are ...
Li Jiebing - - 2007
Uronic acids can be quantified either by a colorimetric determination after treatment with concentrated sulfuric acid and carbazole or by gas chromatography after methanolysis and subsequent acetylation. Both methods suffer from incomplete hydrolysis, an unavoidable degradation of the products to be analysed, and an inability to separate and quantify different ...
Mo Cui-Yun - - 2007
An alternatively minimizing covariant matrix error (AMCME) algorithm, newly proposed by the present authors, was applied to the simultaneous fluorometric determination of pyridoxal, pyridoxamine and 4-pyridoxic acid without loss of sensitivity. The experimental results illustrate that the profiles of spectra and concentration can be accurately resolved using the AMCME algorithm ...
Xiao Jian Bo - - 2007
Two well known derivatization methods, butylation and methylation, are compared by gas chromatography (GC)-mass spectrometry (MS) to identify organic acids in Bayer liquors. These two derivatization methods should be combined together for the determination of the carboxylic acids. Twenty-four organic acids are identified by GC-MS and 13 organic acids are ...
Liao Lifu - - 2007
A new spectrophotometric titration method coupled with chemometrics for the simultaneous determination of mixtures of weak acids has been developed. In this method, the titrant is a mixture of sodium hydroxide and an acid-base indicator, and the indicator is used to monitor the titration process. In a process of titration, ...
Pérez-Serradilla J A - - 2007
A study of the feasibility of focused microwave-assisted Soxhlet extraction of acorn oil and comparison of results from analysis of trans fatty acids in the oil thus obtained with those for oils obtained by use of other methods commonly used for oil extraction are reported here. The proposed method was ...
Liu Peng - - 2007
A reversed phase high-performance liquid chromatography method was established for the first time to simultaneously qualify the seven major diterpenoids in Pseudolarix kaempferi, namely pseudolaric acid B O-beta-D-glucopyranoside (1), pseudolaric acid C2 (2), pseudolaric acid C1 (3), deacetylpseudolaric acid A (4), pseudolaric acid A O-beta-D-glucopyranoside (5), pseudolaric acid B (6) ...
Foulon C - - 2007
Acidity constants of benzoxa-, benzothia- and benzoselena-zolinone derivatives were determined by capillary electrophoresis, potentiometry and spectrophotometry experiments. These three analytical techniques gave pK(a) results that were in good agreement. A convenient, accurate and precise method for the determination of pK(a) was developed to measure changes in acidity constants induced by ...
El-Aroud Khalifa Abulghasem - - 2007
Two simple and sensitive spectrophotometric and fluorimetric methods for the determination of tranexamic acid in tablets are developed. The methods are based on condensation the primary amino group of tranexamic acid with acetyl acetone and formaldehyde producing a yellow coloured product, which is measured spectrophotometrically at 335 nm or fluorimetrically ...
Badadani Mallikarjun - - 2007
BACKGROUND: Assay of urinary imino acids, in particular peptide derived, is of immense utility in diagnosis of collagen-related disorders. The often-used methods for hydrolysis of urinary peptides need a long time and are cumbersome, hence the need for relatively simpler, but effective methods. METHODS: The method described, based on alkaline ...
Wilson Jeffrey Daniel - - 2007
This is a systematic study that examines several acid prewashes and water rinses on paper bearing latent prints before its treatment with a silver physical developer. Specimens or items processed with this method are usually pretreated with an acid wash to neutralize calcium carbonate from the paper before the treatment ...
Chen Mei-Lan - - 2007
In this paper, a method based on ion chromatography (IC) with conductivity detector was developed for the determination of impurities including phenyl phosphinic acid (BPA), phenyl phosphonic acid (PPOA) and crylic acid in flame retardant monomer 2-carboxyl ethyl(phenyl) phosphinic acid (CEPPA). Under favorable chromatographic conditions, good linear relationship, sensitivity and ...
Hasani Masoumeh - - 2007
A spectrophotometric method for simultaneous analysis of glycine and lysine is proposed by application of neural networks on the spectral kinetic data. The method is based on the reaction of glycine and lysine with 1,2-naphthoquinone-4-sulfonate (NQS) in slightly basic medium. On the basis of the difference in the rate between ...
Dais Photis - - 2007
The present study was designed to assess the agreement between analytical methodologies based on 1H and 31P NMR spectroscopy and conventional analytical methods (titration, gas chromatography, and high performance liquid chromatography) for measuring certain minor and major constituents (free acidity, fatty acids, iodine value, and phenolic compounds) of olive oil. ...
Wang L - - 2007
This work aimed at developing a procedure for spore quantification. Spore content was determined by analyzing dipicolinic acid (dpa) extracted from aerobic granules by 13 methods. Concentrated HCl was able to release dpa completely. Results showed that dpa constituted 33.7 mg per g SS, meaning that about 337 mg per ...
Baghel Anuradha - - 2007
In this study, a rapid colorimetric method for arsenic detection was developed. Different reagents containing magnesium turnings in combination with a series of acids were tested for arsine generation. The arsine was then allowed to react with auric chloride on Whatman filter paper No. 3, which in turn changed color. ...
Song Jing-Zheng - - 2007
A rapid ion-pair HPLC method was developed and validated for the determination of eight polyprenylated xanthones including three pairs of epimers, namely morellic acid (MA), 30-hydroxygambogic acid (HGA), 30-hydroxyepigambogic acid (HEGA), isogambogic acid (IGA), epiisogambogic acid (EIGA), gambogenic acid (GNA), gambogic acid (GA), and epigambogic acid (EGA), in gamboge resin ...
Laffargue Andréina - - 2007
In order to develop a sensitive and reliable method for FFA quantification in lipid matrices of seeds, two SPE procedures employed in meat and dairy chemistry were compared using a 100/1 mixture of triolein/heptadecanoic acid. The overall efficiency of the SPE procedure retained was satisfactory since it allowed removal of ...
Rimmelin-Maury Peggy - - 2007
A novel method is proposed to determine concentrations of silicic acid in seawater in the nanomolar range of 3-500 nM. It preconcentrates silicic acid through a "Magnesium Induced Co-precipitation" (MAGIC) step before a classical spectrophotometric measurement. The detection limit (3+/-2 nM) is improved by a factor 10 in comparison to ...
Walthall David A - - 2007
The gas-phase acidities of the vinyl hydrogens of cis- and trans-2-butene were measured by the silane kinetic method in a Fourier-transform ion cyclotron resonance spectrometer. The acidities of ethene and the secondary vinyl hydrogen of propene were measured by the same method. The method was calibrated using the known acidities ...
Furrer Patrick - - 2007
Standard chromatographic methods for the quantification of bacterial poly(3-hydroxyalkanoate) (PHA) proved to be inappropriate for the analysis of medium-chain-length PHA (mcl-PHA). Transesterification catalyzed by protic acids is not quantitative for mcl-PHA under common conditions due to slow reaction kinetics and formation of side-products in case of functionalized side-chains. To circumvent ...
Seco-Gesto Eva María - - 2007
Studies on the application of a short microwave irradiation cycle and the use of diluted acids to extract trace elements from raft mussel samples were developed. Multi-element determinations (Al, Ba, Cd, Cr, Cu, Fe, Mn, Pb, Sn, V and Zn) were carried out by inductively coupled plasma-optical emission spectrometry (ICP-OES). ...
Frank Michael P - - 2007
A simple and rapid high performance liquid chromatographic method for the determination of plasma amino acids was developed. The method uses minimal sample volume and automated online precolumn derivitization of amino acids with o-phthalaldehyde and fluorescent detection. Amino acids are separated by a simplified gradient without column heating. The assay ...
Han Chunfang - - 2007
With UV irradiation, Hg(2+) in aqueous solution can be converted into Hg(0) cold vapor by low molecular weight alcohols, aldehydes, or carboxylic acids, e.g., methanol, formaldehyde, acetaldehyde, glycol, 1,2-propanediol, glycerol, acetic acid, oxalic acid, or malonic acid. It was found that the presence of nano-TiO(2) more or less improved the ...
Nagababu Enika - - 2007
Recent studies have demonstrated that plasma nitrite (NO2-) reflects endothelial nitric oxide synthase activity and it has been proposed as a prognostic marker for cardiovascular disease. In addition, NO2- itself has been shown to have biological activities thought to be triggered by reduction back to NO in blood and tissues. ...
Cunchillos C - - 2007
Metabolic pathways exhibit structures resulting from an evolutionary process. Pathways have been inherited through time with modification, from the earliest periods of life. It is possible to compare the structure of pathways as done in comparative anatomy, i.e. for inferring ancestral pathways or parts of it (ancestral enzymatic functions), using ...
Berregi Iñaki - - 2007
A quantitative determination method of formic acid in apple juices is proposed by means of the proton nuclear magnetic resonance ((1)H NMR) technique. Formic acid gives a singlet signal at the 8.2-8.4ppm interval of the spectrum, and its area is used to determine the concentration of the acid. 1,3,5-Benzenetricarboxylic acid ...
Komersová Alena - - 2007
The original Ellman's spectrophotometrical method for cholinesterase activity determination uses 5,5'-dithiobis-2-nitrobenzoic acid (DTNB, Ellman's reagent) as a chromogen and records the level of cholinesterase activity as an increase of absorbance at 412 nm. Although this procedure usually poses no problem, exceptions arise when the concentration of DTNB is far higher ...
Wang Ting - - 2007
A new spectrofluorimetric method was developed for the determination of trace amounts of bile acid (BA). Using europium ion (Eu(3+))-doxycycline (DC) as a fluorescent probe, in a buffer solution of pH=7.0, BA can remarkably reduce the fluorescence intensity of the DC-Eu(3+) complex at lambda=612 nm; the reduced fluorescence intensity of ...
Yang Ping - - 2007
A novel CL method for the determination of tannic acid (TA) was established based on TA inhibition of the chemiluminescence (CL) emission of the luminol-hydrogen peroxide CL system catalysed by tetrasulphonated manganese phthalocyanine (MnTSPc) under alkaline conditions. The peak height is proportional to the natural logarithm of concentration of TA ...
Gouveia-Oliveira Rodrigo - - 2007
BACKGROUND: Some amino acid residues functionally interact with each other. This interaction will result in an evolutionary co-variation between these residues - coevolution. Our goal is to find these coevolving residues. RESULTS: We present six new methods for detecting coevolving residues. Among other things, we suggest measures that are variants ...
Sun Ying-Xue - - 2007
The ion chromatography combined solid phase extraction (SPE) method was developed for the analysis of low concentration haloacetic acids (HAAs), a class of disinfection by-products formed from chlorination of hospital wastewater. The monitored HAAs included monochloroacetic acid, monobromoacetic acid, dichloroacetic acid, dibromoacetic acid and trichloroacetic acid. The method employed a ...
Corso Gaetano - - 2007
A new method to analyze free amino acids using desorption electrospray ionization (DESI) has been implemented. The method is based on the neutral loss mode determination of underivatized amino acids using a tandem quadrupole mass spectrometer equipped with an unmodified atmospheric interface. Qualitative and quantitative optimization of DESI parameters, including ...
Abdel-Hamid Mohammed - - 2007
OBJECTIVE: The aim of this work was to develop a specific and validated tandem mass spectrometric (MS/MS) method for screening of amino acidopathies, organic acidurias, urea cycle disorders and fatty acid oxidation defects in Kuwaiti newborns and sick infants. MATERIALS AND METHODS: A total of 1,520 blood samples were tested ...
Huang Ting-Lin - - 2007
A new method (NMM, using acetic acid fiber filter and 90% ethanol) was established to determine chlorophyll in freshwater algae, and it was compared with US standard method (USM, using glass fiber filter and 90% acetone) and the method recommend by EPA of China (CHM, using acetic acid fiber filter ...
Pettinella Caterina - - 2007
The quantitative analysis of fatty acid composition in atherosclerotic plaques provides a way to monitor the underlying etiology of atherosclerosis. Previously, the method of choice for analyzing fatty acids in biological samples was gas chromatography/mass spectrometry (GC/MS); however, recent developments in electrospray ionization (ESI)/liquid chromatography (LC)/tandem mass spectrometry have made ...
Chi George T - - 2007
The Fenton oxidation process is one of the most widely used technologies in the oxidation of organic pollutants. The identification and quantification of end products of these oxidation processes is of prime importance due to environmental concerns of pollution and toxicity. In this work, we have developed a highly sensitive, ...
Foyle Thomas - - 2007
To determine the overall efficiency of processes designed to convert lignocellulosic polysaccharides to ethanol, it is first necessary to determine the composition of the lignocellulosic substrates. Three standard methods routinely referenced in the literature for this purpose are monoethanolamine, trifluoroacetic acid and concentrated sulphuric acid-based methods. However, in the course ...
Kac Javor - - 2007
A new HPLC method with coulometric detection for the quantification of xanthohumol, alpha-acids and beta-acids in hops was developed. The separation of compounds was accomplished with a C18 column and isocratic elution with methanol: 50 mM potassium phosphate: ortho-phosphoric acid=80:20:0.25 (v/v/v). The method was validated and UV and electrochemical detectors ...
Käkölä Jaana - - 2007
The versatile characterization of organic material and especially of the significant aliphatic hydroxy acids in black liquor is of great importance, for example, in monitoring the progress of the kraft pulping process. This paper describes a simple high-performance liquid chromatographic separation method with atmospheric-pressure chemical ionization mass spectrometry (HPLC-APCI-MS) which ...
Laamanen Pirkko-Leena - - 2007
A capillary zone electrophoresis (CZE) method for analyzing 11 chelating agents [beta-alaninediacetic acid (beta-ADA), trans-1,2-diaminocyclohexane-N,N,N',N'-tetraacetic acid (CDTA), diethylenetriaminepentaacetic acid (DTPA), ethylenediaminetetraacetic acid (EDTA), N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid (HEDTA), N-(2-hydroxyethyl)iminodiacetic acid (HEIDA), iminodiacetic acid (IDA), methylglycinediacetic acid (MGDA), nitrilotriacetic acid (NTA), 1,3-diaminopropane-N,N,N',N'-tetraacetic acid (PDTA) and triethylenetetraaminehexaacetic acid (TTHA)] as negatively charged copper(II) complexes ...
Croxton Ruth S - - 2006
Latent fingerprint residue is a complex mixture of organic and inorganic compounds. A full understanding of the composition of this mixture and how it changes after deposition is lacking. Three solvent systems were compared for the simultaneous extraction and derivatization with ethyl chloroformate of selected amino and fatty acids from ...
Zhao Guohua - - 2007
A method based on hollow fiber supported liquid membrane extraction coupled with a gas chromatograph equipped with flame ionization detector (GC-FID) was developed for the determination of six short-chain fatty acids including acetic acid, propionic acid, i-butyric acid, n-butyric acid, i-valeric acid and n-valeric acid in serum. Hollow fiber supported ...
Clarke Gerard - - 2007
The amino acid neurotransmitters gamma-aminobutyric acid (GABA) and glutamate have been implicated in mood disorders and high performance liquid chromatography (HPLC) is an important method in their quantitation. This paper describes a method which employs either electrochemical or fluorescent detection of the amino acid derivatives formed by a reaction with ...
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