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https://www.readbyqxmd.com/read/28727449/the-use-of-maldi-ms-combined-with-differential-hydrogen-deuterium-exchange-for-semi-automated-protein-global-conformational-screening
#1
Gregory F Pirrone, Heather Wang, Nicole Canfield, Alexander S Chin, Timothy A Rhodes, Alexey A Makarov
Matrix-assisted laser desorption/ionization (MALDI) coupled with a time-of-flight (TOF) mass-spectrometry (MS) detector is acknowledged to be very useful for analysis of biological molecules. At the same time, hydrogen-deuterium exchange (HDX) is a well-known technique for studying protein higher-order structure. However, coupling MALDI with HDX may be challenging due to undesired back-exchange reactions during analysis. In this report, we survey an approach that utilizes MALDI coupled with automated sample preparation to compare global conformational changes of proteins under different solution conditions using differential HDX...
July 20, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28726757/characterization-of-essential-oil-composition-in-different-basil-species-and-pot-cultures-by-a-gc-ms-method
#2
Andrea Muráriková, Anton Ťažký, Jarmila Neugebauerová, Alexandra Planková, Josef Jampílek, Pavel Mučaji, Peter Mikuš
Basil (Ocimum L.) species are used as medicinal plants due to their essential oils exhibiting specific biological activity. The present work demonstrated that both the variety and season/conditions of cultivation had a significant effect on (i) the produced amount (extraction yield), (ii) qualitative, as well as (iii) quantitative profile of basil essential oil. Among studied basil varieties, a new variety, 'Mánes', was characterized for the first time. Based on our quantitative evaluation of GC-MS profiles, the following chemotypes and average concentrations of a main component were detected in the studied basil varieties: 'Ohře', 'Lettuce Leaf', 'Purple Opaal', 'Dark Green' (linalool, 5...
July 20, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/28725084/development-of-a-single-drop-microextraction-with-derivatization-procedure-for-analysis-of-volatile-fatty-acids-in-water-samples
#3
Grażyna Wejnerowska
A single-drop microextraction (SDME) was developed for the analysis of volatile fatty acids (VFAs) (C2-C7) in water by gas chromatography (GC) with flame ionization detection. The significant parameters affecting the SDME performance such as selection of microextraction solvent, extraction time, stirring rate, sample pH and temperature, and ionic strength were studied and optimized. To lower limits of detection, derivatization of VFAs by N-methyl-N-(tert-butyldimethylsilyl)trifluoroacetamide (MTBSTFA) was performed...
2017: Chromatographia
https://www.readbyqxmd.com/read/28722506/diffusion-weighted-magnetic-resonance-imaging-of-parotid-glands-before-and-after-abatacept-therapy-in-patients-with-sj%C3%A3-gren-s-syndrome-associated-with-rheumatoid-arthritis-utility-to-evaluate-and-predict-response-to-treatment
#4
Hiroyuki Takahashi, Hiroto Tsuboi, Masahiro Yokosawa, Hiromitsu Asashima, Tomoya Hirota, Yuya Kondo, Isao Matsumoto, Takayuki Sumida
OBJECTIVE: To compare parotid diffusion-weighted images (DWIs) taken before and after abatacept therapy in patients with Sjögren's syndrome (SS) associated with rheumatoid arthritis (RA) and to examine the utility in evaluation and prediction of response to therapy. METHODS: DWIs of the parotid glands taken at baseline and 52 weeks after initiation of abatacept were analyzed in nine SS patients with RA using relative standard deviation (RSD) of the entire glands and signal intensity ratio (SIR) within the residual parenchyma...
July 19, 2017: Modern Rheumatology
https://www.readbyqxmd.com/read/28720177/validation-of-multiresidue-method-for-analysis-of-31-pesticides-in-rice-using-gas-chromatography-tandem-mass-spectrometry
#5
Rahul Mondal, Ramen Kumar Kole, Anjan Bhttacharyya
Five modified QuEChERS were tested for the multiresidue analysis of 31 pesticides in rice. Rice was spiked with mixture solution of pesticides at 10 ng/g. Method selection was based on the LODs (sensitivity) and recovery tests (accuracy) of the pesticides. Analysis was done in GC-tandem MS in multiple reaction monitoring mode with a total run time of approximately 37 min. The selected method was validated after spiking rice at 20 and 100 ng/g in rice. The performance characteristics of the method impacted for all selected pesticides were acceptable according to the guidelines for method validation (recovery of 70-120% with an RSD of <20% and r2 value of ≥0...
July 1, 2017: Journal of AOAC International
https://www.readbyqxmd.com/read/28720176/determination-of-polycyclic-aromatic-hydrocarbons-in-commercial-parenteral-formulations-and-medications-using-high-performance-liquid-chromatography-with-diode-array-detection
#6
Marcia M Barichello, Denise Bohrer, Carine Viana, Leandro M Carvalho, Paulo C Nascimento
HPLC coupled to UV diode array detection (DAD) is proposed for the determination of polycyclic aromatic hydrocarbons (PAHs) in pharmaceutical products for parenteral administration. Because rubber is a possible source of PAHs for these products, samples stored in containers with rubber parts were selected for the analysis. The basis for method optimization was EPA Method 8310, which determines 16 priority PAHs in ground water and wastewater by HPLC using both UV and fluorescence detection. Using DAD, two channels were selected for detection, with one operating at 254 nm for the detection of nine PAHs and the other at 225 nm for the detection of seven PAHs...
July 1, 2017: Journal of AOAC International
https://www.readbyqxmd.com/read/28717336/validation-of-a-stability-indicating-spectrometric-method-for-the-determination-of-sulfacetamide-sodium-in-pure-form-and-ophthalmic-preparations
#7
Sofia Ahmed, Noureen Anwar, Muhammad Ali Sheraz, Iqbal Ahmad
INTRODUCTION: Sulfacetamide sodium is a widely used sulfonamide for ophthalmic infections. OBJECTIVE: A number of analytical methods have been reported for the analysis of sulfacetamide but they lack the ability to determine both the active drug and its major degradation product, sulfanilamide, simultaneously in a sample. MATERIALS AND METHODS: In the present study a simple, rapid and economical stability-indicating UV spectrometric method has been validated for the simultaneous assay of sulfacetamide sodium and sulfanilamide in pure form and in ophthalmic preparations...
April 2017: Journal of Pharmacy & Bioallied Sciences
https://www.readbyqxmd.com/read/28714305/a-spme-based-ca-history-method-for-measuring-svoc-diffusion-coefficients-in-clothing-material
#8
Jianping Cao, Ningrui Liu, Yinping Zhang
Clothes play an important role in dermal exposure to indoor semi-volatile organic compounds (SVOCs). The diffusion coefficient of SVOCs in clothing material (Dm) is essential for estimating SVOC sorption by clothing material and subsequent dermal exposure to SVOCs. However, few studies have reported the measured Dm for clothing materials. In this paper, we present the solid-phase micro-extraction (SPME) based Ca-history method. To the best of our knowledge, this is the first try to measure Dm with known relative standard deviation (RSD)...
July 17, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28707885/continuous-and-inexpensive-monitoring-of-non-purgeable-organic-carbon-by-coupling-high-efficiency-photo-oxidation-vapor-generation-to-miniaturized-point-discharge-optical-emission-spectrometry
#9
Shu Zhang, Yunfei Tian, Hongling Yin, Yubin Su, Li Wu, Xiandeng Hou, Chengbin Zheng
Currently, no applicable analyzers are available to accomplish online and continuous monitoring of organic pollution, which is one of the most important factors contributing to water shortages around the world, particularly in developing countries. In this work, a sensitive, miniaturized, inexpensive, on-line and continuous non-purgeable organic carbon (NPOC) analysis system was developed for the continuous monitoring of such organic pollution. This system consists of a specially designed and high efficiency UV photo-oxidation vapor generation (HE-POVG) reactor and a miniaturized, low power (7 W) point discharge microplasma optical emission spectrometer (PD-OES)...
July 14, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28699574/a-new-turn-on-fluorometric-detection-method-for-the-determination-of-ag-i-in-some-food-and-water-samples
#10
Şerİfe Saçmaci, Mustafa Sa X Maci, Ahmet Ülgen
A new sensitive and selective turn-on fluorometry procedure for the determination of silver using a laboratory-built fluorometry system is described herein. After synthesis and characterization, a [2-((E)-{[3′,6′-bis(ethylamino)-2′,7′-dimethyl-3-oxospiro[isoindole-1,9′-xanthen]-2(3H)-yl]imino}methyl)cyclopenta-2,4-dien-1-yl] (cyclopenta-2,4-dien-1-yl)iron (DKMS) fluorescent reagent was used for the first time. Ag(I) was complexed with the new fluorescent reagent, and direct measurements were made using fluorometry without any separation/preconcentration...
July 12, 2017: Journal of AOAC International
https://www.readbyqxmd.com/read/28699007/assessment-of-nonsteroidal-anti-inflammatory-drugs-by-ultrasonic-assisted-extraction-and-gc-ms-in-mgeni-and-msunduzi-river-sediments-kwazulu-natal-south-africa
#11
Bhekumuzi P Gumbi, Brenda Moodley, Grace Birungi, Patrick G Ndungu
The occurrence of eight pharmaceuticals was monitored during four seasons (spring, summer, autumn, and winter) along a 250-km stretch of the Msunduzi and Mgeni rivers in KwaZulu-Natal, South Africa. This paper describes an optimized method for the determination of nonsteroidal anti-inflammatory drugs (NSAIDs) in sediments. The method combines ultrasonic, centrifuge, and gas chromatography-mass spectrometry for the detection of these drugs in solid samples. Most of the parameters that affect the extraction step were optimized...
July 11, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28697415/a-high-area-porous-and-resistant-platinized-stainless-steel-fiber-coated-by-nanostructured-polypyrrole-for-direct-hs-spme-of-nicotine-in-biological-samples-prior-to-gc-fid-quantification
#12
Sana Abdolhosseini, Alireza Ghiasvand, Nahid Heidari
The surface of a stainless steel fiber was made porous, resistant and cohesive using electrophoretic deposition and coated by the nanostructured polypyrrole using an amended in-situ electropolymerization method. The coated fiber was applied for direct extraction of nicotine in biological samples through a headspace solid-phase microextraction (HS-SPME) method followed by GC-FID determination. The effects of the important experimental variables on the efficiency of the developed HS-SPME-GC-FID method, including pH of sample solution, extraction temperature and time, stirring rate, and ionic strength were evaluated and optimized...
June 27, 2017: Journal of Chromatography. B, Analytical Technologies in the Biomedical and Life Sciences
https://www.readbyqxmd.com/read/28694398/renal-sympathetic-denervation-assisted-treatment-of-electrical-storm-due-to-polymorphic-ventricular-tachycardia-in-a-patient-with-cathecolaminergic-polymorphic-ventricular-tachycardia
#13
Tolga Aksu, Tümer Erdem Güler, Kazım Serhan Özcan, Serdar Bozyel, Kıvanç Yalın
Electrical storm (ES) is not a rare clinical entity. Sympathetic hyperactivity may play critical role in development and continuation of ES. Some recent reports have demonstrated that catheter-based renal sympathetic denervation (RSD) may reduce sympathetic activation and have a potential role in reducing arrhythmic burden. A 46-year-old man was admitted to clinic with frequent implantable cardioverter defibrillator shocks and ES related to catecholaminergic polymorphic ventricular tachycardia (VT). Tachycardia was unresponsive to administration of beta-blockers, verapamil, and flecainide...
July 2017: Türk Kardiyoloji Derneği Arşivi: Türk Kardiyoloji Derneğinin Yayın Organıdır
https://www.readbyqxmd.com/read/28690260/rapid-quantification-of-n-methyl-2-pyrrolidone-in-polymer-matrices-by-thermal-desorption-gc-ms
#14
Young-Min Kim, Jae Woo Kim, Hye Mi Moon, Min-Jin Lee, Akihiko Hosaka, Atsushi Watanabe, Norio Teramae, Young-Kwon Park, Seung-Woon Myung
Analysis of a residual solvent in polymeric materials has become an important issue due to the increased regulations and standards for its use. N-Methyl-2-pyrrolidone (NMP) is a solvent widely used in many industries and restricted as one of the chemicals under EU REACH regulations due to its potential harmful effects. In this study, thermal desorption-gas chromatography/mass spectrometry (TD-GC/MS) is applied for the quantitative analysis of NMP with the use of a polymer-coated sample cup. By using the polymer-coated sample cup, the vaporization of NMP was prevented during waiting time before TD-GC/MS analysis...
2017: Analytical Sciences: the International Journal of the Japan Society for Analytical Chemistry
https://www.readbyqxmd.com/read/28689323/a-sensitive-colorimetric-assay-system-for-nucleic-acid-detection-based-on-isothermal-signal-amplification-technology
#15
Bo Hu, Jing Guo, Ying Xu, Hua Wei, Guojie Zhao, Yifu Guan
Rapid and accurate detection of microRNAs in biological systems is of great importance. Here, we report the development of a visual colorimetric assay which possesses the high amplification capabilities and high selectivity of the rolling circle amplification (RCA) method and the simplicity and convenience of gold nanoparticles used as a signal indicator. The designed padlock probe recognizes the target miRNA and is circularized, and then acts as the template to extend the target miRNA into a long single-stranded nucleotide chain of many tandem repeats of nucleotide sequences...
July 8, 2017: Analytical and Bioanalytical Chemistry
https://www.readbyqxmd.com/read/28688915/targeted-proteome-analysis-with-isotope-coded-protein-labels-for-monitoring-the-influence-of-dietary-phytochemicals-on-the-expression-of-cytoprotective-proteins-in-primary-human-colon-cells
#16
Christiane Östreicher, Sven Bartenbacher, Monika Pischetsrieder
Cytoprotective effects by upregulating cellular expression levels of antioxidant proteins are attributed to a significant number of food ingredients. Evaluation of those cytoprotective effects and identification of the most active components requires reliable and comprehensive proteomic strategies. Thus, promising potential bioactive ingredients could be determined for the prevention of various diseases, including colon cancer formation. We established a multiplexed nanoLC-MS/MS targeted proteomic method, operated in scheduled selected reaction monitoring mode (sSRM), to record modulation of the expression levels of six major antioxidant proteins induced by dietary phytochemicals...
July 6, 2017: Journal of Proteomics
https://www.readbyqxmd.com/read/28688308/a-pcr-free-electrochemical-method-for-messenger-rna-detection-in-cancer-tissue-samples
#17
Md Nazmul Islam, Vinod Gopalan, Md Hakimul Haque, Mostafa Kamal Masud, Md Shahriar Al Hossain, Yusuke Yamauchi, Nam-Trung Nguyen, Alfred King-Yin Lam, Muhammad J A Shiddiky
Despite having reliable and excellent diagnostic performances, the currently available messenger RNA (mRNA) detection methods mostly use enzymatic amplification steps of the target mRNA which is generally affected by the sample manipulations, amplification bias and longer assay time. This paper reports an amplification-free electrochemical approach for the sensitive and selective detection of mRNA using a screen-printed gold electrode (SPE-Au). The target mRNA is selectively isolated by magnetic separation and adsorbed directly onto an unmodified SPE-Au...
June 27, 2017: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/28687993/rapid-total-sulphur-reduction-in-coal-samples-using-various-dilute-alkaline-leaching-reagents-under-microwave-heating-preventing-sulphur-emissions-during-coal-processing
#18
Nomvano Mketo, Philiswa Nosizo Nomngongo, Jane Catherine Ngila
Currently in South Africa, online flue gas desulphurisation (FGD) is being utilized as one of the most effective methods for total sulphur reduction in coal samples during the combustion process. However, the main disadvantage associated with FGD is the formation of its by-products (FGD gypsum). The latter is mostly formed in low grade quality, thereby bringing secondary pollution problems and extra disposal costs. Therefore, the current study describes the development of total sulphur extraction in coal under microwave heating using different dilute alkaline solutions such as NaOH, NaOH-H2O2, NH4OH, and NH4OH-H2O2...
July 7, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28686919/a-simple-and-low-cost-dual-wavelength-%C3%AE-correction-spectrophotometric-determination-and-speciation-of-mercury-ii-in-water-using-chromogenic-reagent-4-2-thiazolylazo-resorcinol
#19
A H Al-Bagawi, W Ahmad, Z M Saigl, H Alwael, E A Al-Harbi, M S El-Shahawi
The most common problems in spectrophotometric determination of various complex species originate from the background spectral interference. Thus, the present study aimed to overcome the spectral matrix interference for the precise analysis and speciation of mercury(II) in water by dual-wavelength β-correction spectrophotometry using 4-(2-thiazolylazo) resorcinol (TAR) as chromogenic reagent. The principle was based on measuring the correct absorbance for the formed complex of mercury(II) ions with TAR reagent at 547nm (lambda max)...
July 1, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28683189/development-of-a-uhplc-ms-ms-method-for-the-quantitation-of-bioactive-compounds-in-phyllanthus-species-and-its-herbal-formulations
#20
Sunil Kumar, Awantika Singh, Vikas Bajpai, Bikarma Singh, Brijesh Kumar
Phyllanthus species are extensively used in traditional medicines for the treatment of hepatic diseases due to their bioactive hypophyllanthin and phyllanthin since ancient times. This work describes the development and validation of an ultra high performance liquid chromatography with tandem mass spectrometry method in polarity switching multiple reaction monitoring mode for the simultaneous detection and quantitation of 23 compounds using ultra performance liquid chromatography coupled with electrospray-hybrid triple quadrupole-linear ion trap mass spectrometer...
July 6, 2017: Journal of Separation Science
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