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Results 201 - 250 of 1640
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Guo Sheng - - 2009
A simple and sensitive HPLC-DAD method has been developed for the first time to simultaneously determine 10 triterpenoid acids (ceanothic acid, alphitolic acid, zizyberanal acid, zizyberanalic acid, epiceanothic acid, ceanothenic acid, betulinic acid, oleanolic acid, ursonic acid and zizyberenalic acid) in the dried fruit of Ziziphus jujuba (called Dazao) which ...
Rafamantanana M H - - 2009
The simultaneous quantification of madecassoside, asiaticoside, madecassic acid and asiatic acid in Centella asiatica by HPLC-UV is proposed. Asiaticoside was used as reference for the quantification of heterosides and asiatic acid for aglycones. The evaluation of the extraction efficiency of the four molecules led to use Soxhlet extraction for 8 ...
Gómez Edison Díaz - - 2009
Enantiopure alpha-amino acids were converted to 4-substituted 2-aryl- and 2-alkyl-5(4H)-oxazolones under partial racemization. These nonracemic mixtures were dissolved in CDCl(3), an equimolar amount of the chiral dirhodium complex Rh(II)(2)[(R)-(+)-MTPA](4) (MTPA-H = Mosher's acid) was added, and the (1)H NMR spectra of the resulting samples were recorded (dirhodium method). The relative ...
Dias Jailson C - - 2009
A new chromatographic method for the sequential determination of short-chain fatty acids is described. Acetic, propionic and butyric acids were determined in dietary fiber extracts using ion-exclusion chromatography equipped with inverse chemical suppression and conductivity detection. The best optimization of the chromatographic conditions were achieved when a 100 mm x ...
Nozawa Yuriko - - 2009
In the advanced Marfey's method, the resolution between the diastereomers derivatized with 1-fluoro-2,4-dinitrophenyl-5-L-leucinamide (L-FDLA) and 1-fluoro-2,4-dinitrophenyl-5-D-leucinamide (D-FDLA) is reflected by the difference of hydrophobicity of the two functional groups at the asymmetric carbon. However, no effective method has been developed for the estimation of hydrophobicity so far. For this purpose, ...
Sibrell Philip L - - 2009
Excess phosphorus in wastewaters promotes eutrophication in receiving waterways. A cost-effective method for the removal of phosphorus from water would significantly reduce the impact of such wastewaters on the environment. Acid mine drainage sludge is a waste product produced by the neutralization of acid mine drainage, and consists mainly of ...
Tonidandel Loris - - 2009
Baltic amber contains high levels of succinic acid, most of which is part of the polymer framework, and only recently has the presence of microcrystals of free succinic acid been documented by scanning electron microscopy and X-ray diffraction analysis. The determination of succinic acid can be used for an easy ...
Fukuzawa Kenji - - 2009
The ferric-xylenol orange (FOX) method has been used for quantification of hydroperoxides by measuring the colored ferric-xylenol orange (XO/Fe3+) product with a peak absorbance at 560 nm. We recently reported a modified FOX method, the sensitivity of which was increased in the presence of membranous phosphatidylcholine (PC) by forming a ...
Mayoral Jaime G - - 2010
A novel end-point fluorimetric procedure based on the use of rhodamine-110-labeled specific substrate was developed to determine trypsin activities in biological samples. We evaluated the ability of trichloroacetic acid and acetic acid to stop the enzymatic reaction without hindering the detection of the fluorescence of rhodamine-110 released into the reaction ...
Tomàs Albert - - 2009
A rapid methodology for direct analysis of meat acylglycerides is proposed. A transesterification is carried out in a microwave reactor consisting of a monomode oven using chlorotrimethylsilane (CTMS) and methanol. High-temperature gas chromatography was used to check the absence of underivatized acylglycerides. Whereas transesterification is complete after 30s at 90 ...
Patane Jonathan J Department of Chemistry, California State University, Sacramento, CA 95819-6057, - - 2009
The hydrolysis of colominic acid via microwave irradiation was studied for the production of short-chain oligomers with a degree of polymerization (DP) of 1-5. This method was compared to the traditional acid hydrolytic method for the production of preparative quantities of short colominic acid oligomers. The oligomers were purified by ...
Fukuda Shinji - - 2009
BACKGROUND: Environmental processes in ecosystems are dynamically altered by several metabolic responses in microorganisms, including intracellular sensing and pumping, battle for survival, and supply of or competition for nutrients. Notably, intestinal bacteria maintain homeostatic balance in mammals via multiple dynamic biochemical reactions to produce several metabolites from undigested food, and ...
Xu Yawei - - 2009
A novel boronic acid functionalized mesoporous silica, which holds the attractive features of high surface area and large accessible porosity, was developed to enrich glycopeptides. This is the first time that mesoporous material has been introduced into glycoproteome. In comparison to direct (traditional) analysis, this novel method enabled 2 orders ...
Strable E - - 2009
Protein capsids derived from viruses may be modified by methods, generated, isolated, and purified on large scales with relative ease. In recent years, methods for their chemical derivatization have been employed to broaden the properties and functions accessible to investigators desiring monodisperse, atomic-resolution structures on the nanometer scale. Here we ...
Yasaka Yoshiro - - 2009
A sensitive in situ NMR spectroscopic method for detecting acids contaminating ionic liquids (ILs) has been developed. The chemical shift and the spectral width of water added to ILs were used as indicators to measure the impurity acid level. Owing to the high resolution power of NMR, the detection limit ...
Kristl Albin - - 2009
The pharmacological characteristics of proton pump inhibitors are related to their protolytic behavior estimated by their pK(a) values. Lansoprazole is a potent anti-acid drug from this group. Because of its poor stability a rapid spectrophotometric method was developed for the determination of its pK(a) values. Three pK(a) values were obtained: ...
Odeku Oluwatoyin A - - 2009
Starches obtained from four different Dioscorea species namely White (D. rotundata), Bitter (D. dumetorum), Chinese (D. oppositifolia) and Water yam (D. alata), were modified by acid hydrolysis and the physicochemical, material and tablet formation properties of the starches were investigated with the aim of determining their usefulness as a direct ...
Si Hua-Yan - - 2009
A new type of nanohybrids containing carbon nanotubes (CNTs) and CdSe quantum dots (QDs) was prepared using an electrostatic self-assembly method. The CdSe QDs were capped by various mercaptocarboxylic acids, including thioglycolic acid (TGA), dihydrolipoic acid (DHLA) and mercaptoundecanoic acid (MUA), which provide shell thicknesses of ~5.2, 10.6 and 15.2 ...
Gupta Abhay - - 2009
The purpose of this work was to evaluate and compare the functionality of bovine fatty acids-derived (MgSt-B) and vegetable fatty acids-derived (MgSt-V) magnesium stearate powders when used for the lubrication of granules prepared by high-shear (HSG) and fluid bed (FBG) wet granulation methods. The work included evaluation of tablet compression ...
Lee Mi Kyoung - - 2009
A simple and rapid reversed-phase HPLC-UV method was developed for the determination of triterpenic acids in the crude extract of Prunellae Spica. Five triterpenic acids were extracted and isolated from P. Spica as marker compounds for use in the quality control of herbal medicines. Various solvent extraction techniques were evaluated, ...
Han Ting - - 2009
A high-performance liquid chromatographic method using diode-array detection and electrospray ionization tandem mass spectrometry (HPLC-DAD-ESI-MS/MS) was developed for the qualitative and quantitative analysis on Xanthium fruit, a commonly used traditional Chinese medicine. In this study, 7 characteristic components, 1-O-caffeoylquinic acid, 4-O-caffeoylquinic acid, chlorogenic acid, 1,5-O-di-caffeoylquinic acid, 1,3-O-di-caffeoylquinic acid, 4,5-O-di-caffeoylquinic acid ...
Eilola Keijo - - 2009
A microwave-assisted double insert multimode vapour-phase digestion method was developed for the digestion of organic samples. The experimental set-up was based on a third generation-type teflon microwave vessel, equipped with an automatic pressure regulating type vessel cover. A borosilicate glass holder insert, containing a smaller quartz sample insert, was fitted ...
Nassef Hossam M - - 2008
Celiac disease is a gluten-sensitive enteropathy that affects as much as 1% of the population. Patients with celiac disease should maintain a lifelong gluten-free diet, in order to avoid serious complications and consequences. It is essential to have methods of analysis to reliably control the contents of gluten-free foods, and ...
Spano Nadia - - 2009
In this study 5-hydroxymethyl-2-furaldehyde (HMF), 2-furaldehyde, 3-furaldehyde, 2-furoic acid and 3-furoic acid are contemporarily determined in honey using a swift and direct RP-HPLC approach. The validation protocol was performed in terms of detection and quantification limits, precision (by repeatability and reproducibility), linearity and accuracy (by recovery tests); the acceptability of ...
Gambino Grazia Laura - - 2008
A simple and reliable high-performance liquid chromatographic method that uses photodiode array detection was developed for the simultaneous determination of 12 native and synthetic plant hormones, i.e., plant growth regulators (PGRs), in fertilizers, such as 1-naphthol, 2,4-dichlorophenoxyacetic acid, 4-(2,4-dichlorophenoxy)butyric acid, 4-chlorophenoxyacetic acid, indole-3-acetic acid, 4-(3-indolyl)butyric acid, dichlorprop, (4-chloro-2-methylphenoxy)acetic acid, alpha-naphthaleneacetic ...
Nassef Hossam M - - 2008
Celiac disease is a gluten-sensitive enteropathy that affects as much as 1% of the population. Patients with celiac disease should maintain a lifelong gluten-free diet, in order to avoid serious complications and consequences. It is essential to have methods of analysis to reliably control the contents of gluten-free foods, and ...
Huang Hsi-Ya - - 2009
In this study, a sample stacking step coupled with microemulsion electrokinetic chromatography (MEEKC) was used to detect and analyze nine aromatic acids (benzoic acid (BA), isophthalic acid (IPA), terephthalic acid (TPA), p-toluic acid (p-TA), 4-carboxylbenzaldehyde (4-CBA), trimesic acid (TSA), trimellitic acid (TMA), o-phthalic acid (OPA), and hemimellitic acid (HMA)) which ...
Lin Teng Shee Fabrice - - 2008
Chitosan, a linear polysaccharide composed of beta-1,4 linked d-glucosamine residues, can be depolymerized into oligomers by enzymatic reaction with chitosanase. Recently, bipolar membrane electrodialysis (BMED) has been used for chitosan solubilization and for terminating the enzymatic reaction by action of electrogenerated acid and base, respectively. The aim of the present ...
Kubec Roman - - 2008
A novel method for determination of S-alk(en)ylcysteine-S-oxides by capillary electrophoresis has been developed and validated. The method is based on extraction of these sulfur amino acids by methanol, their derivatization by fluorenylmethyl chloroformate and subsequent separation by micellar electrokinetic capillary chromatography. Main advantages of the new method are simplicity, sensitivity, ...
Qiao Jun-Qin - - 2009
A high-performance liquid chromatographic method was proposed for the separation of relative impurities in industrial 3-methylflavone-8-carboxylic acid (MFCA) and its intermediate methyl 3-propionylsalicylate (MPS). Benzoic acid (BA), MPS, 6-chloro-3-methylflavone-8-carboxylic acid (MFCA-Cl) and methyl 5-chloro-3-propionylsalicylate (MPS-Cl) in MFCA, and MPS-Cl in MPS were respectively quantified by an external standard method. As ...
Marles M A Susan - - 2008
Legumes with high concentrations of condensed tannin (pinto bean [Phaseolus vulgaris L.], sainfoin [Onobrychis viciifolia Scop.], and big trefoil [Lotus uliginosus Hoff.]), were compared to a selection of forages, with low or zero condensed tannin (smooth bromegrass [ Bromus inermis Leyss], Lotus japonicus [Regel] K. Larsen, and alfalfa [Medicago sativa ...
Araujo Pedro P National Institute of Nutrition and Seafood Research, N-5817 Bergen, Norway. - - 2008
A simplified method for quantitative analysis of fatty acids in various matrices by gas chromatography is proposed as an alternative to the conventional method and the variables of the protocol examined to optimize the processing conditions. The modified method involves direct methylation of fatty acids in homogenized samples with boron ...
Cho Ki Woong - - 2008
A new bioluminescent assay method for the activity of sphingolipid ceramide N-deacylase (SCDase: EC 3.5.1.69) as well as ceramidase (CDase: EC 3.5.1.23) was developed using bioluminescent marine bacteria. Enzymatically synthesized ceramide (N-myristoyl sphigosine, C14:0-18:l) and commercial SCDase were used in this demonstration, and myristic (tetradecanoic, C14:0) acid produced by the ...
Varelis P - - 2008
For the determination of melamine and cyanuric acid the labelled internal standards [(13)C(3)]-melamine and [(13)C(3)]-cyanuric acid were synthesized using the common substrate [(13)C(3)]-cyanuric chloride by reaction with ammonia and acidified water, respectively. Standards with excellent isotopic and chemical purities were obtained in acceptable yields. These compounds were used to develop ...
Guo Nan - - 2009
OBJECTIVE: To evaluate the effectiveness of microwave-assisted acid hydrolysis of proteins combined with MALDI-TOF MS to characterize hemoglobin G Coushatta. DESIGN AND METHOD: Following separation of the globin chains, the purified beta chain fractions were hydrolyzed by acid hydrolysis prior to MALDI-TOF MS. RESULTS: The method correctly identified the abnormal ...
Yagasaki Makoto - - 2008
The functions and applications of L-alpha-dipeptides (dipeptides) have been poorly studied compared with proteins or amino acids. Only a few dipeptides, such as aspartame (L-aspartyl-L-phenylalanine methyl ester) and L-alanyl-L-glutamine (Ala-Gln), are commercially used. This can be attributed to the lack of an efficient process for dipeptide production though various chemical ...
Drochioiu Gabi - - 2008
The total cyanogenic potential of various substrates (flax seed, stones of peach, plum, nectarine and apricot as well as apple seeds, and various model compounds) was investigated by using the acid hydrolysis method, picrate method, and a novel method based on the reaction of cyanide liberated from plants with resorcinol ...
Li Minyong M Department of Chemistry and Center for Biotechnology and Drug Design, Georgia State University, Atlanta, Georgia 30302-4098, - - 2008
The first general method for the selection of boronic acid-based aptamers (boronolectins) that allows for glycan substructure focusing is described. Using fibrinogen as a model glycoprotein, we have selected boronic acid-modified DNA aptamers that have high affinities (low nM Kd) and the ability to recognize changes in the glycosylation site. ...
Chen He - - 2008
In the present study, a simple and sensitive photo-induced chemiluminescence (CL) method for the quantitation of reducing sugars, including fructose, glucose, sucrose and lactose, was developed. This method was based on the on-line photocatalytic reaction of the reducing sugars, using a home-made photoreactor consisting of PTEF tube helically coiling around ...
Kalkanci Ayse - - 2008
The in vitro activity ofAMPH-B, 5-FC, FLCZ, MCZ, ITCZ, and VRCZ against 50 isolates of T. asahii was determined using CLSI M27-A2 microdilution and ASTY colorimetric methods. Observed agreement ranged from 96 to 100% according to the drug. Overall, the agreement between two methods was 97.7%. The ASTY colorimetric method ...
Zamani Akram - - 2008
A new method was developed to determine glucosamine (GlcN) and N-acetyl glucosamine (GlcNAc) in materials containing chitin and chitosan, such as fungal cell walls. It is based on two steps of hydrolysis with (i) concentrated sulfuric acid at low temperature and (ii) dilute sulfuric acid at high temperature, followed by ...
Scott Angela C - - 2008
The extraction of bitumen from the oil sands in Canada releases toxic naphthenic acids into the process-affected waters. The development of an ideal analytical method for quantifying naphthenic acids (general formula C(n)H(2n+Z)O(2)) has been impeded by the complexity of these mixtures and the challenges of differentiating naphthenic acids from other ...
Leung Diana D Department of Chemistry and Biochemistry, The University of Texas at Austin, 1 University Station A5300, Austin, Texas 78712, - - 2008
Enantioselective indicator displacement assays (eIDAs) were used for the determination of enantiomeric excess (ee) of alpha-amino acids as an alternative to the labor-intensive technique of chromatography. In this study, eIDAs were implemented by the use of two chiral receptors [(Cu(II)(1)](2+), [Cu(II)(2)](2+)) in conjunction with the indicator chrome azurol S. The ...
Kangani Cyrous O - - 2008
A simple, direct and accurate method for the determination of concentration and enrichment of free fatty acids (FFAs) in human plasma was developed. The validation and comparison to a conventional method are reported. Three amide derivatives, dimethyl, diethyl and pyrrolidide, were investigated in order to achieve optimal resolution of the ...
Tsai Ying I - - 2008
This paper describes a novel gradient elution ion chromatographic method using a Dionex AS11 system for the determination of low molecular weight dicarboxylic acids (low-M(w) DCAs) in background atmospheric aerosol. Interference with the oxalic acid peak from sulfate in background PM(2.5) aerosol, 15.8 times the oxalic acid concentration, was remedied ...
Sadanaga Yasuhiro - - 2008
An in situ nitric acid analyzer has been designed for sensing in the remote atmosphere. Its operation is based on measuring the concentration difference between the total odd nitrogen species (NO(y)) and HNO(3)-scrubbed NO(y). NO(y) was measured by an NO-ozone chemiluminescent detector equipped with a molybdenum converter. A temperature-controlled annular ...
Duangrat Chadarat - - 2008
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. ...
Prabakaran G - - 2008
Bacillus thuringiensis var. israelensis, a gram positive, spore-forming bacillus, produces parasporal crystal protein during sporulation, which is toxic in the mosquito larvae gut. An efficient downstream processing method for separating the spore crystal complex (SCC) from the fermented broth of B. thuringiensis var. israelensis is required to achieve maximum mosquitocidal ...
Basconcillo Libia Saborido - - 2008
Three protocols for fatty acid analysis in Sinorhizobium meliloti were improved by the addition of a number of standards/controls and a silylation step which allowed the determination of recoveries, extents of conversion of lipids to fatty acid methyl esters (FAMEs) and extents of side reactions. Basic hydrolysis followed by acid-catalyzed ...
Stranger Marianne - - 2009
A diffusive sampling method for the determination of gaseous acetic and formic acids, using a radial symmetry diffusive sampler, has been optimised for a 7-day exposure time in this study. Sampling rate determinations were performed on data obtained from a dynamic exposure chamber, simulating the indoor conditions of an empty, ...
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