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Results 301 - 350 of 1645
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Payne Richard J - - 2007
Recently, we reported the development of sugar-assisted ligation (SAL), a novel peptide ligation method for the synthesis of glycopeptides. After screening a large number of glycoprotein sequences in a glycoprotein database, it became evident that a large proportion (approximately 53%) of O-glycosylation sites contain amino acid residues that will not ...
Michel H - - 2008
A new sequential method for the determination of both natural (U, Th) and anthropogenic (Sr, Cs, Pu, Am) radionuclides has been developed for application to soil and sediment samples. The procedure was optimised using a reference sediment (IAEA-368) and reference soils (IAEA-375 and IAEA-326). Reference materials were first digested using ...
Antonelli Marta Letizia - - 2008
Enzymatic microcalorimetry has been successfully employed in the reliable determination of the l-malic acid concentration in some foods and cosmetic products. The l-malic acid concentration during the wine-making process is particularly useful in order to control the progress of the malo-lactic fermentation. Total acidity, taste and flavour characteristics of wine ...
Possanzini Massimiliano - - 2007
The classical derivatization method of carbonyls based on 2,4-dinitrophenylhydrazine (DNPH)-coated silica cartridges was tested to concurrently measure lower carbonyls and carboxylic acids in air samples. The performance of these cartridges with respect to formic and acetic acids was evaluated in a number of laboratory measurements on collection and reaction efficiencies. ...
Klampfl Christian W - - 2007
A comprehensive overview of the analysis of low-molecular-mass organic acids employing electromigration methods in the capillary format is given. This review includes papers published since 2003 and can be seen as an update of the review paper published by Galli et al. in 2003. Tables included in this review contain ...
Lomborg Carina Juel - - 2008
Production monitoring of "natural" 2-heptanone from octanoic acid in an industrial fed-batch cultivation based on Penicillium roqueforti requires development of a method for determination of octanoic acid dissolved in the water phase. An electronic tongue array using six non-specific potentiometric sensors with solid inner contact, and a pH electrode, has ...
Antolín Ernesto Méndez - - 2008
D003 is a new active ingredient consisting of a mixture of very long chain saturated fatty acids (C(24:0)-C(36:0)) in a definite proportion, which shows antioxidant, antiosteoporotic, antiplatelet and cholesterol-lowering effects in experimental models. Five derivatization methods for determining these fatty acids by gas chromatography (GC), using diazomethane, sulphuric acid-methanol, hydrochloric ...
Antoniewicz Maciek R - - 2007
Metabolic flux analysis based on stable-isotope labeling experiments and analysis of mass isotopomer distributions (MID) of cellular metabolites is a tool of great significance for metabolic engineering and study of human disease. This method relies on accurate and precise measurements of mass isotopomers by gas chromatography/mass spectrometry. To improve flux ...
Krizman Mitja - - 2007
An adequate analytical method for determination of amino acids can provide a better insight in the metabolism of in vitro human embryo cultures, increasing the success rate of embryo implantation. Since individual amino acid amounts per embryo occur in the nanogram range, GC was the technique of choice, due to ...
Turchini Giovanni M - - 2007
Currently there are several contrasting methods utilized for estimating elongation and desaturation of fatty acids and their general metabolism. The majority of these methods involve an ex vivo approach, requiring expensive and sophisticated equipment, likely to result in considerable variation in enzyme activity between and within species. In the present ...
Barkawi Lana S - - 2008
To investigate novel pathways involved in auxin biosynthesis, transport, metabolism, and response, we have developed a high-throughput screen for indole-3-acetic acid (IAA) levels. Historically, the quantitative analysis of IAA has been a cumbersome and time-consuming process that does not lend itself to the screening of large numbers of samples. The ...
Mojica Kristina - - 2007
The uronic acids assay was evaluated for its ability to measure the amount of uronic acids contained within a biofilm exopolysaccharide matrix. Cytophaga lytica, a marine bacterium isolated from a naturally occurring biofilm, was used to form single-species biofilms for the method assessment. The assay was found to be simple, ...
Márquez-Ruiz G - - 2007
A new method based on high-performance size-exclusion chromatography (HPSEC) is proposed to quantitate primary and secondary oxidation compounds in model fatty acid methyl esters (FAMEs). The method consists on simply injecting an aliquot sample in HPSEC, without preliminary isolation procedures neither addition of standard internal. Four groups of compounds can ...
Luthra Abhinav - - 2007
Inter-residue potentials are extensively used in the design and evaluation of protein structures. However,dealing with all (20 x 20) interactions becomes computationally difficult in extensive investigations. Hence, it is desirable to reduce the alphabet of 20 amino acids to a smaller number. Currently, several methods of reducing the residue types ...
Qi Jianping - - 2007
A simple, rapid and accurate HPLC method has been developed for simultaneous determination of hydroxysafflor yellow A and ferulic acid in rat plasma after oral administration of the co-extractum of Rhizoma chuanxiong and Flos Carthami. Plasma samples were deproteinized with 6% perchloric acid, and riboflavin was used as internal standard. ...
Chiong Hendrich A - - 2007
Two new palladium-catalyzed methods for the direct ortho-arylation of free benzoic acids have been developed. The first method employs stoichiometric silver acetate for iodide removal, aryl iodide as the coupling partner, and acetic acid solvent. This method is applicable to the arylation of electron-rich to moderately electron-poor benzoic acids and ...
Boer Klas - - 2007
OBJECTIVES: Evaluation of the performance of the EMIT 2000 Cyclosporin assay using 2 sets of assay calibrators and the EMIT 2000 mycophenolic acid assay to measure C0 and C2 concentrations on the Abbott Architect c8000 analyzer. DESIGN AND METHODS: Imprecision studies were performed. Cyclosporin concentration was assayed by EMIT on ...
Arain Mohammad B - - 2007
A simple and efficient procedure for the determination of arsenic (As), cadmium (Cd), and lead (Pb) in the edible parts of freshwater fish by ultrasonic-assisted acid pseudodigestion (USD) was developed. A Plackett-Burman experimental design was used as a multivariate strategy for the evaluation of the effects of several variables at ...
Zhou Chunhua - - 2007
Simple and accurate HPLC methods were developed for the determination of oleanolic acid (OA), ursolic acid (UA) and amygdalin in loquat (Eriobotrya japonica Lindl.) flower, which is commonly used for the treatment of various diseases as a traditional Chinese medicine. HPLC assay was performed on a reversed-phase C(18) column and ...
Sorenson Wendy R WR Covance Laboratories, 3301 Kinsman Blvd, Madison, WI 53704, USA. - - 2007
An interlaboratory study was conducted to evaluate a method for the determination of aristolochic acid I, also known as aristolochic acid A, at levels > 2.00 microg/g in botanical species and dietary supplements potentially contaminated with aristolochic acid I. Aristolochic acid I was extracted from various matrixes with aqueous acetonitrile. ...
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 MP Magee-Womens Research Institute, University of Pittsburgh School of Medicine, 204 Craft Avenue, Pittsburgh, PA 15213, - - 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 ...
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