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Relevant bibliographies by topics / LC-MS methods

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Academic literature on the topic 'LC-MS methods'

Author: Grafiati

Published: 10 March 2023

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Journal articles on the topic "LC-MS methods"

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Chikasou, Masato, Syuichi Inohana, Toshiaki Yokozeki, Hitoshi Tuchiya, and Kazuhiro Fujita. "Development of LC-MS and LC-MS/MS Methods for Free Asparagine in Grains." Food Hygiene and Safety Science (Shokuhin Eiseigaku Zasshi) 59, no. 5 (2018): 248–56. http://dx.doi.org/10.3358/shokueishi.59.248.

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Kobayashi, Hiroko. "Development of Residue Analysis for Pesticides by LC/MS and LC/MS/MS Methods." BUNSEKI KAGAKU 58, no. 12 (2009): 985–97. http://dx.doi.org/10.2116/bunsekikagaku.58.985.

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Viette, Véronique, Denis Hochstrasser, and Marc Fathi. "LC-MS (/MS) in Clinical Toxicology Screening Methods." CHIMIA International Journal for Chemistry 66, no. 5 (2012): 339–42. http://dx.doi.org/10.2533/chimia.2012.339.

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Deng, Pan, Yan Zhan, Xiaoyan Chen, and Dafang Zhong. "Derivatization methods for quantitative bioanalysis by LC–MS/MS." Bioanalysis 4, no. 1 (2012): 49–69. http://dx.doi.org/10.4155/bio.11.298.

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HAYASHI, Takako, and Kenji HAMASE. "Determination of Clenbuterol in Various Edible Parts of Livestock Products by LC-MS/MS and LC-MS/MS/MS Methods." CHROMATOGRAPHY 42, no. 1 (2021): 43–48. http://dx.doi.org/10.15583/jpchrom.2020.021.

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Duggan, Jeffrey, Bailuo Ren, Yan Mao, Lin-Zhi Chen, and Elsy Philip. "LC–MS quantification of protein drugs: validating protein LC–MS methods with predigestion immunocapture." Bioanalysis 8, no. 18 (2016): 1951–64. http://dx.doi.org/10.4155/bio-2016-0137.

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Downs, Melanie L., and Philip Johnson. "Target Selection Strategies for LC-MS/MS Food Allergen Methods." Journal of AOAC INTERNATIONAL 101, no. 1 (2018): 146–51. http://dx.doi.org/10.5740/jaoacint.17-0404.

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Abstract The detection and quantitation of allergens as contaminants in foods using MS is challenging largely due to the requirement to detect proteins in complex, mixed, and often processed matrixes. Such methods necessarily rely on the use of proteotypic peptides as indicators of the presence and amount of allergenic foods. These peptides should represent the allergenic food in question in such a way that their use is both sensitive (no false-negatives) and specific (no false-positives). Choosing such peptides to represent food allergens is beset with issues, including, but not limited to, separated ingredients (e.g., casein and whey), extraction difficulties (particularly from thermally processed foods), and incomplete sequence information, as well as the more common issues associated with protein quantitation in biological samples. Here, we review the workflows that have been used to select peptide targets for food allergen detection. We describe the use and limitations of both in silico-based analyses and experimental methods relying on high-resolution MS. The variation in the way in which target selection is performed highlights a lack of standardization, even around the principles describing what the detection method should achieve. A lack of focus on the food matrixes to which the method will be applied is also apparent during the peptide target selection process. It is hoped that highlighting some of these issues will assist in the generation of MS-based allergen detection methods that will encourage uptake and use by the analytical community at large.

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Lapko, Veniamin N., Patrick S. Miller, G. Paul Brown, et al. "Sensitive glucagon quantification by immunochemical and LC–MS/MS methods." Bioanalysis 5, no. 23 (2013): 2957–72. http://dx.doi.org/10.4155/bio.13.264.

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Vazvaei, Faye, and Jeffrey X. Duggan. "Validation of LC–MS/MS bioanalytical methods for protein therapeutics." Bioanalysis 6, no. 13 (2014): 1739–42. http://dx.doi.org/10.4155/bio.14.125.

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Naidong, Weng, Yu-Luan Chen, Wilson Shou, and Xiangyu Jiang. "Importance of injection solution composition for LC–MS–MS methods." Journal of Pharmaceutical and Biomedical Analysis 26, no. 5-6 (2001): 753–67. http://dx.doi.org/10.1016/s0731-7085(01)00439-3.

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Dissertations / Theses on the topic "LC-MS methods"

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Zhao, Ruoxia. "Investigation of Ribonucleic Acid Post-transcriptional Modifications by Optimized LC-MS/MS Methods." University of Cincinnati / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1623240214971428.

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Sharp, Julia Lynn. "New Statistical Methods for Analyzing Proteomics Data from Affinity Isolation LC-MS/MS Experiments." Thesis, Montana State University, 2007. http://etd.lib.montana.edu/etd/2007/sharp/SharpJ0807.pdf.

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The field of proteomics is exploding with statistical problems waiting to be explored. To obtain information on protein complexes, interactions between protein pairs is initially examined. This exploration is performed using `bait-prey' protein pull-down assays that use a protein affinity agent and an LC-MS/MS (liquid chromatography-tandem mass-spectrometry)-based protein identifcation method. An experiment generates a protein association matrix wherein each column represents a sample from one bait protein, each row represents one prey protein and each cell contains a presence/absence association indicator. The prey protein presence/absence pattern is assessed with a Likelihood Ratio Test (LRT) and simulated LRT p-values. Fisher's Exact Test and a conditional frequency distribution test using generating functions are also used to assess the prey protein observation pattern. Based on the p-value, each prey protein is assigned a category (Specific or Non-Specific) and appraised with respect to the goal and design of the experiment. The Bayes' Odds is calculated for each prey-bait pair in the `Specific' category to estimate the posterior probability that two proteins interact and compared to an approach used by Gilchrist et al. [23]. The method is illustrated using an experiment investigating protein complexes of Shewanella oneidensis MR-1 at the Proteomics Facility of Pacific Northwest National Laboratory (PNNL). The example analysis shows the results to be biologically sensible and more realistic than methods previously used to infer protein - protein associations. While inferring protein-protein associations is of great importance in proteomic studies, the quality of the data is of equal or greater importance. Protein-protein interactions may be inferred incorrectly or not at all depending on the quality of the data. Prior to this thesis, statistical quality control measures have not been incorporated into these experiments. The implementation of traditional Individual/Moving Range (IMR) charts and cumulative sum (cusum) quality control methods for use with pull-down experiment data is studied. These methodologies are illustrated using a standard protein mixture from PNNL. The joint application of IMR and cusum charts promises to provide researchers with information on changes in the mean and variability of the data resulting from control samples run through the mass spectrometer process.

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Li, Lan. "Development of Quantitative LC-MS/MS Methods for the Pharmacological Studies of Anti-Cancer Drugs." Cleveland State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=csu1299117212.

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Nezami, Ranjbar Mohammad Rasoul. "Novel Preprocessing and Normalization Methods for Analysis of GC/LC-MS Data." Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/73499.

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We introduce new methods for preprocessing and normalization of data acquired by gas/liquid chromatography coupled with mass spectrometry (GC/LC-MS). Normalization is desired prior to subsequent statistical analysis to adjust variabilities in ion intensities that are not caused by biological differences. There are different sources of experimental bias including variabilities in sample collection, sample storage, poor experimental design, noise, etc. Also, instrument variability in experiments involving a large number of runs leads to a significant drift in intensity measurements. We propose new normalization methods based on bootstrapping, Gaussian process regression, non-negative matrix factorization (NMF), and Bayesian hierarchical models. These methods model the bias by borrowing information across runs and features. Another novel aspect is utilizing scan-level data to improve the accuracy of quantification. We evaluated the performance of our method using simulated and experimental data. In comparison with several existing methods, the proposed methods yielded significant improvement. Gas chromatography coupled with mass spectrometry (GC-MS) is one of the technologies widely used for qualitative and quantitative analysis of small molecules. In particular, GC coupled to single quadrupole MS can be utilized for targeted analysis by selected ion monitoring (SIM). However, to our knowledge, there are no software tools specifically designed for analysis of GS-SIM-MS data. We introduce SIMAT, a new R package for quantitative analysis of the levels of targeted analytes. SIMAT provides guidance in choosing fragments for a list of targets. This is accomplished through an optimization algorithm that has the capability to select the most appropriate fragments from overlapping peaks based on a pre-specified library of background analytes. The tool also allows visualization of the total ion chromatogram (TIC) of runs and extracted ion chromatogram (EIC) of analytes of interest. Moreover, retention index (RI) calibration can be performed and raw GC-SIM-MS data can be imported in netCDF or NIST mass spectral library (MSL) formats. We evaluated the performance of SIMAT using several experimental data sets. Our results demonstrate that SIMAT performs better than AMDIS and MetaboliteDetector in terms of finding the correct targets in the acquired GC-SIM-MS data and estimating their relative levels.<br>Ph. D.

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Minten, Johanna. "Development of methods for the analysis of polar compounds in environmental matrices using LC/UV and LC/MS /." Stockholm : Department of applied environmental science (ITM), Stockholm University, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-29108.

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Diss. (sammanfattning) Stockholm : Stockholms universitet, 2009.<br>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Submitted. Paper 4: Submitted. Härtill 4 uppsatser.

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Cai, Xiaohan. "¿¿¿¿¿¿Development of Bioanalytical Methods for Clinical Applications and Drug Screening." Cleveland State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=csu1314982525.

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Abbas, Ioana. "Development of LC-MS/MS methods for the quantitative determination of hepcidin-25, a key regulator of iron metabolism." Doctoral thesis, Humboldt-Universität zu Berlin, 2018. http://dx.doi.org/10.18452/19358.

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Hepcidin-25, ein 2000 entdecktes Peptidhormon, das eine Schlüsselrolle im Eisenstoffwechsel spielt, hat das Verständnis von Eisenerkrankungen revolutioniert. In dieser Studie wurde LC gekoppelt mit einem Triple-Quadrupol MS in einer schnellen und robusten Methode zur Quantifizierung von Hepcidin-25 in menschlichem Serum verwendet, welche letztlich in Routine-Laboratorien genutzt werden soll. Zu diesem Zweck wurden zwei Probenvorbereitungsstrategien und zwei komplementäre LC Bedingungen untersucht, wobei eine saure mobile Phase (0,1% TFA) mit einem neuartigen Ansatz unter der Verwendung einer basischen mobilen Phase (0,1% NH3) verglichen wurde. In einem laborinternen Vergleich beider LC-MS/MS Methoden wurde Hepcidin-25 in humanen Proben unter Verwendung der gleichen Kalibrierstandards quantifiziert und eine sehr gute Korrelation der Ergebnisse ermittelt. Hierbei wurde die Analysestrategie mit saurer mobiler Phase als hochsensitiv (LOQ von 0,5 μg/L) und präzise (CV <15%) befunden und als Kandidat einer Referenzmethoden für die Hepcidin-25 Quantifizierung in realen Proben empfohlen. Einer der neuartigen Aspekte der Methodik war die Verwendung von Amino- und Fluor-silanisierten Autosampler-Fläschchen, um die Adsorption des 25 Reste umfassenden Peptids anOberflächen zu reduzieren. Darüber hinaus wurde diese LC-MS/MS-Methode in einer internationalen Ringversuchsstudie eingesetzt, bei der ein sekundäres Referenzmaterial als Kalibrierstandard verwendet wurde, und gemäß des International Consortium for Harmonization of Clinical Laboratory Results (ICHCLR) als optimal bewertet. In dieser Arbeit wurde die Bildung von Hepcidin-Komplexen mit Kupfer(II) untersucht. Die erste Umkehrphasen-chromatographische Trennung von Hepcidin-25/Cu(II) und Hepcidin-25 (Kupfer "frei") wurde unter Verwendung von mobilen Phasen mit 0,1% NH3 erreicht. LC-MS/MS und FTICR-MS wurden für die Charakterisierung der gebildeten Hepcidin-25-Cu(II)-Spezies bei pH-Werten von 11 bzw. 7,4 verwendet.<br>Hepcidin-25, a key iron-regulatory peptide hormone discovered in 2000, has revolutionized the understanding of iron-related pathology. This study applied LC-MS/MS, using the triple quadrupole mass spectrometer, in a rapid and robust analytical strategy for the quantification of hepcidin-25 in human serum, to be implemented in routine laboratories. For this purpose, two sample preparation strategies and two complementary LC conditions were investigated, where the use of acidic mobile phases (0.1% TFA) was compared with a novel approach involving solvents at high pH (0.1% NH3). The application of these LC-MS/MS methods to human samples in an intra-laboratory comparison, using the same hepcidin-25 calibrators, yielded a very good correlation of the results. The LC-MS/MS employing trifluoroacetic acid-based mobile phases was selected as a highly sensitive (LOQ of 0.5 µg/L) and precise (CV<15%) method and was recommended as a reference method candidate for hepcidin-25 quantification in real samples. One of the novel aspects of the methodology was the use of amino- and fluoro-silanized autosampler vials to reduce the interaction of the 25-residue peptide to laboratory glassware surfaces. Moreover, this LC-MS/MS method was used for an international round robin study, applying a secondary reference material as a calibrator and its performance was found to be in the optimal range as defined by the International Consortium for Harmonization of Clinical Laboratory Results (ICHCLR). In this work, the formation of hepcidin-25 complexes with copper(II) was investigated. The first reversed-phase chromatographic separation of hepcidin-25/Cu2+ and hepcidin-25 (copper “free”) was achieved by applying mobile phases containing 0.1% NH3. LC-MS/MS and FTICR-MS were applied for the characterization of the formed hepcidin-25-Cu(II) species at pH values of 11 and 7.4 respectively. A new species corresponding to hepcidin-25 complexed with two copper ions was identified at high pH.

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Barclay, Victoria K. H. "Development of LC-MS/MS Methods for the Analysis of Chiral and Achiral Pharmaceuticals and Metabolites in Aqueous Environmental Matrices." Doctoral thesis, Uppsala universitet, Avdelningen för analytisk farmaceutisk kemi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-171550.

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This thesis describes the development of liquid chromatography tandem mass spectrometry (LC-MS/MS) methods for the trace analysis of active pharmaceutical ingredients (APIs) and their metabolites in aqueous environmental matrices. The research was focused on the development of chiral LC-MS/MS methods for the analysis of fluoxetine and metoprolol, as well as their chiral metabolites in environmental water samples. A method was also developed for the achiral compounds, diazepam and nordiazepam. The LC-MS/MS methods were validated by the use of the isotope-labeled compounds. As these isotope-labeled compounds were not found in the wastewater samples, the validation could be assessed at trace level concentrations in the actual matrices in which the analytes were detected. The analytes were extracted from the water samples using solid phase extraction methods. Different types of solid phase extraction sorbents were evaluated. Fluoxetine and norfluoxetine were extracted through the use of a mixed mode polymeric based extraction sorbent. A hydrophilic and lipophilic balanced sorbent was employed for the simultaneous extraction of metoprolol and its metabolites, the base α-hydroxymetoprolol and the acidic metabolite deaminated metoprolol. Moreover, silica based C18 extraction discs were applied for the sample preparation of diazepam and nordiazepam. The chromatographic separations were conducted in reversed phase LC with MS compatible mobile phases. The enantiomers of fluoxetine and norfluoxetine were simultaneously separated using the chiral stationary phase (CSP), α1-acid glycoprotein (AGP). The Chiral AGP column was also applied for the separation of the enantiomers of deaminated metoprolol. For the simultaneous separation of the metoprolol enantiomers and the four stereoisomers of α-hydroxymetoprolol, the cellobiohydrolase (CBH) protein based CSP was used. An octadecyl silica based LC column was applied for the separation of diazepam and nordiazepam. The analytes were detected by the use of tandem quadrupole mass spectrometry operating in selective reactive monitoring mode. High resolution MS, employing a quadrupole time-of-flight (QqTOF) mass analyzer, was utilized for the identification of an unknown compound in wastewater samples. The APIs and their metabolites, as well as their respective enantiomers, were quantified in raw and treated wastewater from Uppsala, Sweden along with surface water from the River Fyris in Uppsala.

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Wabuyele, Simuli Lindah. "DEVELOPMENT OF LC-MS/MS METHODS FOR QUANTITATIVE ANALYSIS OF PLANT-DERIVED ANTICANCER AGENT AND SYNTHETIC ESTROGEN IN COMPLEX MATRICES." Cleveland State University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=csu1400262843.

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Fujisawa, Alma. "Development of chemical labeling methods for organelle molecule analysis." Kyoto University, 2019. http://hdl.handle.net/2433/243315.

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Books on the topic "LC-MS methods"

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LC-MS/MS in proteomics: Methods and applications. Humana Press, 2010.

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LC/MS applications in drug development. J. Wiley & Sones, 2002.

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Cutillas, Pedro R., and John F. Timms. LC-MS/MS in Proteomics: Methods and Applications. Humana Press, 2016.

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Hubschmann, Hans-Joachim. Automated Sample Preparation: Methods for GC-MS and LC-MS. Wiley & Sons, Incorporated, John, 2021.

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Hubschmann, Hans-Joachim. Automated Sample Preparation: Methods for GC-MS and LC-MS. Wiley & Sons, Incorporated, John, 2021.

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Hubschmann, Hans-Joachim. Automated Sample Preparation: Methods for GC-MS and LC-MS. Wiley & Sons, Incorporated, John, 2021.

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Hubschmann, Hans-Joachim. Automated Sample Preparation: Methods for GC-MS and LC-MS. Wiley & Sons, Incorporated, John, 2021.

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Halket, John, and Steve Down. LC/MS Methods: An Essential Tool to Accelerate Methods Development. Global View Pub, 2007.

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Langman, Loralie J., and Christine L. H. Snozek. LC-MS in Drug Analysis: Methods and Protocols. Springer New York, 2019.

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Langman, Loralie J., and Christine L. H. Snozek. LC-MS in Drug Analysis: Methods and Protocols. Springer New York, 2018.

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Book chapters on the topic "LC-MS methods"

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Huang, Lihua, and P. Clayton Gough. "Characterization of PEGylated Biopharmaceutical Products by LC/MS and LC/MS/MS." In Methods in Molecular Biology. Humana Press, 2012. http://dx.doi.org/10.1007/978-1-61779-921-1_22.

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Want, Elizabeth J. "LC-MS Untargeted Analysis." In Methods in Molecular Biology. Springer New York, 2018. http://dx.doi.org/10.1007/978-1-4939-7643-0_7.

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Bajad, Sunil, and Vladimir Shulaev. "LC-MS-Based Metabolomics." In Methods in Molecular Biology. Humana Press, 2010. http://dx.doi.org/10.1007/978-1-61737-985-7_13.

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Krautbauer, Sabrina, and Gerhard Liebisch. "LC-MS/MS Analysis of Bile Acids." In Methods in Molecular Biology. Springer New York, 2018. http://dx.doi.org/10.1007/978-1-4939-7592-1_8.

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Chalkley, Robert. "Instrumentation for LC-MS/MS in Proteomics." In Methods in Molecular Biology. Humana Press, 2010. http://dx.doi.org/10.1007/978-1-60761-780-8_3.

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Jacob, Richard J. "Bioinformatics for LC-MS/MS-Based Proteomics." In Methods in Molecular Biology. Humana Press, 2010. http://dx.doi.org/10.1007/978-1-60761-780-8_4.

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Korman, Eric W., Loralie J. Langman, and Christine L. H. Snozek. "Hypoglycemic Agent Screening by LC-MS/MS." In Methods in Molecular Biology. Humana Press, 2012. http://dx.doi.org/10.1007/978-1-61779-934-1_13.

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Garby, David M., and Lynn A. Cheryk. "Synthetic Opioid Analysis by LC-MS/MS." In Methods in Molecular Biology. Humana Press, 2012. http://dx.doi.org/10.1007/978-1-61779-934-1_6.

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Snozek, Christine L. H., Matthew W. Bjergum, and Loralie J. Langman. "Cocaine and Metabolites by LC-MS/MS." In Methods in Molecular Biology. Humana Press, 2012. http://dx.doi.org/10.1007/978-1-61779-934-1_8.

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Häkkinen, Merja R. "Polyamine Analysis by LC-MS." In Methods in Molecular Biology. Humana Press, 2011. http://dx.doi.org/10.1007/978-1-61779-034-8_33.

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Conference papers on the topic "LC-MS methods"

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Vlaic, Sebastian, Robert Altwasser, Peter Kupfer, et al. "Inference of Predictive Phospho-regulatory Networks from LC-MS/MS Phosphoproteomics Data." In 7th International Conference on Bioinformatics Models, Methods and Algorithms. SCITEPRESS - Science and and Technology Publications, 2016. http://dx.doi.org/10.5220/0005743000850091.

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Ranjbar, Mohammad R. Nezami, Yi Zhao, Mahlet G. Tadesse, Yue Wang, and Habtom W. Ressom. "Evaluation of normalization methods for analysis of LC-MS data." In 2012 IEEE International Conference on Bioinformatics and Biomedicine Workshops (BIBMW). IEEE, 2012. http://dx.doi.org/10.1109/bibmw.2012.6470209.

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Kubczak, Christian, Tiziana Margaria, Arno Fritsch, and Bernhard Steffen. "Biological LC/MS Preprocessing and Analysis with jABC, jETI and xcms." In Second International Symposium on Leveraging Applications of Formal Methods, Verification and Validation (isola 2006). IEEE, 2006. http://dx.doi.org/10.1109/isola.2006.48.

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Magni, Paola. "Entomotoxicology: Development and validation of CG-MS and LC/MS-MS methods for nicotine, metanfetamine, endosulfan, and coumatetraryl detection in blowflies." In 2016 International Congress of Entomology. Entomological Society of America, 2016. http://dx.doi.org/10.1603/ice.2016.94572.

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He, Kai, John Heckel, Vittoria Balsamo De Hernandez, and Duy Nguyen. "Application of LC-MS and Methyl Orange Methods for Improved Residual Surfactant Detection in Liquids-Rich Shale Plays." In SPE Western Regional Meeting. SPE, 2021. http://dx.doi.org/10.2118/200774-ms.

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Abstract Successful field trials of surfactant-based Production Enhancement (PROE) technology in different shale plays including Permian Basin, Bakken and Eagle Ford indicate that specially tailored surfactant formulations can improve the unconventional well productivity during flowback and production. One major challenge for the operator is to further optimize the surfactant dosage to maximize the economic return. Analysis of the residual surfactant concentration in the produced water (PW) might provide a new path to optimize the surfactant application in the field. Such quantitative measurements can help understand how much surfactant is consumed in the downhole and how much surfactant is in the flowback, and possibly correlate back to the well performance. Additionally, surfactant partitioning and adsorption behaviors can be studied through residual analysis, which will further provide guidance to develop next generation of surfactant formulations. In this study, a liquid chromatography-mass spectrometry (LC-MS) method was developed to accurately measure the residual surfactant concentration in the produced water. The liquid chromatograph (LC) separates the surfactant from sample matrix and avoids the possible interference, and then the mass spectrometer (MS) detects the separated surfactant, signal correlating to the residual concentration. This analytical method provides unrivalled selectivity and specificity compared to other methods reported in the literature. In addition, a Methyl Orange method was developed and can potentially be used in the field for quicker measurements. Produced water samples collected from a Huff-and-Puff treatment in the Permian Basin were evaluated using both methods. Our results indicate that both methods can successfully capture the trend of residual concentration vs. production time. The deviation between LC-MS and Methyl Orange measurements was due to the presence of ADBAC (alkyldimethylbenzylammonium chloride) in the produced water, which is a cationic amine surfactant typically used as biocide in the well stimulation. It produces positive interference and thus leads to a higher residual detection in the Methyl Orange test. Notably, the residual concentration of surfactant in produced water decreased with time after the well was placed back to production, which is consistent with the concept that more surfactant will adsorb to the rock surface or partition into the oil phase over production time. In summary, we believe the LC-MS and Methyl Orange methods can potentially be used to detect residual concentration for any type of surfactant-based applications in unconventional reservoirs including Huff-and-Puff, completion, frac protect, surfactant flooding and re-frac. The field application of surfactant-based chemistry followed by this type of residual analysis can help understand the underlying mechanisms of the surfactant and provide further guidance for production optimization of shales.

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SILVA, Bruno Pereira da, Gabriel RÜBENSAM, Claudiela Wachholz SAAFELD, and João Batista Blessmann WEBER. "RELEASE PROFILE OF BISPHENOL-A FROM DENTAL RESINS IN WATER ASSESSED BY LC-MS/MS." In SOUTHERN BRAZILIAN JOURNAL OF CHEMISTRY 2021 INTERNATIONAL VIRTUAL CONFERENCE. DR. D. SCIENTIFIC CONSULTING, 2022. http://dx.doi.org/10.48141/sbjchem.21scon.23_abstract_rubensan.pdf.

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Dental resins have been designed to replace amalgam restorations due to their more favorable physical, chemical, and biological properties. However, depending on its composition, the efficiency of its polymerization, and the degradation of the polymer matrix, Bisphenol-A can be present and therefore released from this material to the human body. It has been reported that residues of additives and minority by-products of polymer reactions, such as Bisphenol-A, can be released from plastics into aqueous media through polymer hydration, water-polymer diffusion, residue dissolution, and equilibrium between dissolved residues in water and polymer. Over time, this could lead to a polymer material with an external layer practically free of Bisphenol-A. However, the newly formed layer could be removed by brushing during oral cleaning, similar to toothbrushing, exposing the new layer containing Bisphenol-A to the aqueous media. Due to the toxic effects of this compound, an increasing number of plastics labeled as BPA-free have been introduced to the dental market, including tooth coating, dental sealants, and resins. Nevertheless, more specific studies on analytical chemistry have revealed a trace of Bisphenol-A in dental resins labeled as BPA-free and pointed out the need for even more sensitive and accurate detection methods to help manufacturers evaluate the presence of background contaminations in their products and to avoid false-negative results. In this way, liquid chromatography-tandem mass spectrometry has been considered one of the most suitable methods for confirming Bisphenol-A even at low concentrations, in high complex matrices, due to its high select sensitivity. In the present work, we developed a sensitive, reliable, and efficient approach to trace the release profile of Bisphenol-A by LC-MS/MS in dental resin samples purchased in the Brazilian dental market. With the analysis of five different brands of resin composites performed in eight days of exposition to water, four of them released Bisphenol-A from 3.4 pg/mm2 to 10.1 ng/mm2. The brand labeled as BPA-free released BPA at concentrations of 1.1 ng/mm2. However, one sample reached the maximum of released BPA in only 3 days, one in 4 days, and two virtually did not reach a maximum of BPA released into the water in the window time assessed. Limits of detection and quantification of the LC-MS/MS method were 40 pg/mm2 and 100 pg/mm2, respectively, and allowed the quantification of BPA released from a composite labeled as BPA-free. For future analysis, we will conduct a more comprehensive study on the release profile of BPA from resin composites into the water using a tooth brushing simulator to determine if the obtained profiles might have clinical implications.

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Liu, Zhiqian, and Simone Rochfort. "Current challenges in phospholipid analysis in bovine milk." In 2022 AOCS Annual Meeting & Expo. American Oil Chemists' Society (AOCS), 2022. http://dx.doi.org/10.21748/taft4078.

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Phospholipids (PLs) are important components of milk fat globule membranes. They not only play the role of emulsifier ensuring the stability and homogeneity of the oil/water emulsion system of milk, but also have multiple beneficial functions vis-Ã -vis human health. PLs of milk are a complex family of polar lipids comprising several classes including PC, PE, SM, PS, PI, PA, PG and so on and each class contains a mixture of hundreds of molecular species differing in fatty acid (FA) composition and/or regio-position.Although PL quantification at the class level can be achieved by using NP-LC-ELSD and 31P-NMR, LC-MS (mainly HILIC-MS and RP-LC-MS) has become the prevalent analytical system for PL identification and quantification at the molecular species level. Unfortunately, combining LC separation with high-resolution MS detection is still insufficient to differentiate FA regio-isomers and double bond (DB) positional isomers, both being widely present in milk PLs. Additional techniques such as ozonolysis, UV-photodissociation and photochemical tagging in combination with LC-MS are needed for a complete structural characterization of PLs.Despite the recent progress, huge challenges remain to be overcome both in PL identification and quantification. This talk will discuss these in conjunction with the following aspects of bovine milk PLs. 1) pros and cons of different LC-MS methods in PL identification and quantification; 2) major PL class and species identified so far in bovine milk and 3) utility of Paterno-Buchi photochemical reaction in revealing regio-isomer and DB-positional isomers.

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8

Liebisch, Gerhard, Marcus Horing, and Sabrina Krautbauer. "Quantification of minor lipid species in mammalian samples - strategies and pitfalls." In 2022 AOCS Annual Meeting & Expo. American Oil Chemists' Society (AOCS), 2022. http://dx.doi.org/10.21748/spyw2337.

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The mammalian lipidome represents a complex mixture of lipid molecules. Although major lipid classes are quantifiable by direct infusion mass spectrometry in crude lipid extracts, minor lipid species typically require LC-separation coupled to tandem mass spectrometry (LC-MS/MS) to increase sensitivity and specificity. Matrix effects are a key obstacle in quantitative electrospray ionization (ESI) mass spectrometry, typically compensated by addition of internal standards (ISs) and their co-ionization with the corresponding analyte. Furthermore, to avoid misidentification, it is important to ensure separation of isomeric structures and to resolve isobaric interference, the so-called Type II overlap present in lipid classes with double bond series.Here, we will discuss strategies to address these analytical challenges based on LC-MS/MS methods established in our laboratory. Accurate quantification of minor glycerophospholipids and sphingolipids, as well as bile acids, will be discussed, including potential pitfalls.

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Beteinakis, S., P. Stathopoulos, D. Michailidis, et al. "Comparative quantitative and qualitative studies of extra virgin olive oil using HPTLC, HPLC-DAD, NMR, LC-HRMS & MS/MS methods." In GA 2017 – Book of Abstracts. Georg Thieme Verlag KG, 2017. http://dx.doi.org/10.1055/s-0037-1608520.

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Blebea, Nicoleta Mirela, and Simona Negreș. "METHODS FOR QUANTIFICATION OF THE MAIN CANNABINOIDS IN CBD OIL." In GEOLINKS Conference Proceedings. Saima Consult Ltd, 2021. http://dx.doi.org/10.32008/geolinks2021/b1/v3/13.

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Cannabidiol (CBD) is an alkaloid present in Cannabis sativa, together with tetrahydrocannabinol (THC) and more than 120 other substances belonging to a group of compounds named cannabinoids. Due to the continuous increased usage of CBD oils, it became necessary to be developed efficient methods for the identification of its compounds and especially for the characterization of the cannabinoids from the commercial specimens. Cannabinoids may be detected by many and different analytical methods, including immunoassays (EMIT®, Elisa, fluorescent polarization, radioimmunotest), techniques of flat chromatography: classic thin layer chromatography (TLC), optimum performance laminar chromatography (OPLC) and multiple development automatization (AMD), gas chromatography-mass spectrometry (GC-MS), high-performance liquid chromatography-mass spectrometry (HPLC-MS). Ultraviolet signal (UV) is used for the quantification of major cannabinoids and the mass spectrometer is used for the quantification of minor cannabinoids. The purpose of this study was to compare the performances of TLC, Ultra High-Performance Liquid chromatography with Photodiode Array Detection (UHPLC with PDA) and LC-MS/ MS technique for the qualitative and quantitative determination of cannabinoids in 3 commercial oils with CBD. Having in view that CBD may be found in many forms of oils, on the legal market of the internet, we believe that the development of a method for the qualitative and quantitative determination may be an interesting subject for the pharmaceutical professional persons.

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Reports on the topic "LC-MS methods"

1

Desai, Meera Jay. Development of Chiral LC-MS Methods for small Molecules and Their Applications in the Analysis of Enantiomeric Composition and Pharmacokinetic Studies. Office of Scientific and Technical Information (OSTI), 2004. http://dx.doi.org/10.2172/837266.

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2

Lehotay, Steven J., and Aviv Amirav. Fast, practical, and effective approach for the analysis of hazardous chemicals in the food supply. United States Department of Agriculture, 2007. http://dx.doi.org/10.32747/2007.7695587.bard.

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Background to the topic: For food safety and security reasons, hundreds of pesticides, veterinary drugs, and environmental pollutants should be monitored in the food supply, but current methods are too time-consuming, laborious, and expensive. As a result, only a tiny fraction of the food is tested for a limited number of contaminants. Original proposal objectives: Our main original goal was to develop fast, practical, and effective new approaches for the analysis of hazardous chemicals in the food supply. We proposed to extend the QuEChERS approach to more pesticides, veterinary drugs and pollutants, further develop GC-MS and LC-MS with SMB and combine QuEChERS with GC-SMB-MS and LC-SMB-EI-MS to provide the “ultimate” approach for the analysis of hazardous chemicals in food. Major conclusions, solutions and achievements: The original QuEChERS method was validated for more than 200 pesticide residues in a variety of food crops. For the few basic pesticides for which the method gave lower recoveries, an extensive solvent suitability study was conducted, and a buffering modification was made to improve results for difficult analytes. Furthermore, evaluation of the QuEChERS approach for fatty matrices, including olives and its oil, was performed. The QuEChERS concept was also extended to acrylamide analysis in foods. Other advanced techniques to improve speed, ease, and effectiveness of chemical residue analysis were also successfully developed and/or evaluated, which include: a simple and inexpensive solvent-in-silicone-tube extraction approach for highly sensitive detection of nonpolar pesticides in GC; ruggedness testing of low-pressure GC-MS for 3-fold faster separations; optimization and extensive evaluation of analyte protectants in GC-MS; and use of prototypical commercial automated direct sample introduction devices for GC-MS. GC-MS with SMB was further developed and combined with the Varian 1200 GCMS/ MS system, resulting in a new type of GC-MS with advanced capabilities. Careful attention was given to the subject of GC-MS sensitivity and its LOD for difficult to analyze samples such as thermally labile pesticides or those with weak or no molecular ions, and record low LOD were demonstrated and discussed. The new approach of electron ionization LC-MS with SMB was developed, its key components of sample vaporization nozzle and flythrough ion source were improved and was evaluated with a range of samples, including carbamate pesticides. A new method and software based on IAA were developed and tested on a range of pesticides in agricultural matrices. This IAA method and software in combination with GC-MS and SMB provide extremely high confidence in sample identification. A new type of comprehensive GCxGC (based on flow modulation) was uniquely combined with GC-MS with SMB, and we demonstrated improved pesticide separation and identification in complex agricultural matrices using this novel approach. An improved device for aroma sample collection and introduction (SnifProbe) was further developed and favorably compared with SPME for coffee aroma sampling. Implications, both scientific and agricultural: We succeeded in achieving significant improvements in the analysis of hazardous chemicals in the food supply, from easy sample preparation approaches, through sample analysis by advanced new types of GC-MS and LCMS techniques, all the way to improved data analysis by lowering LOD and providing greater confidence in chemical identification. As a result, the combination of the QuEChERS approach, new and superior instrumentation, and the novel monitoring methods that were developed will enable vastly reduced time and cost of analysis, increased analytical scope, and a higher monitoring rate. This provides better enforcement, an added impetus for farmers to use good agricultural practices, improved food safety and security, increased trade, and greater consumer confidence in the food supply.

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Fluhr, Robert, and Maor Bar-Peled. Novel Lectin Controls Wound-responses in Arabidopsis. United States Department of Agriculture, 2012. http://dx.doi.org/10.32747/2012.7697123.bard.

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Innate immune responses in animals and plants involve receptors that recognize microbe-associated molecules. In plants, one set of this defense system is characterized by large families of TIR–nucleotide binding site–leucine-rich repeat (TIR-NBS-LRR) resistance genes. The direct interaction between plant proteins harboring the TIR domain with proteins that transmit and facilitate a signaling pathway has yet to be shown. The Arabidopsis genome encodes TIR-domain containing genes that lack NBS and LRR whose functions are unknown. Here we investigated the functional role of such protein, TLW1 (TIR LECTIN WOUNDRESPONSIVE1). The TLW1 gene encodes a protein with two domains: a TIR domain linked to a lectin-containing domain. Our specific aim in this proposal was to examine the ramifications of the TL1-glycan interaction by; A) The functional characterization of TL1 activity in the context of plant wound response and B) Examine the hypothesis that wounding induced specific polysaccharides and examine them as candidates for TL-1 interactive glycan compounds. The Weizmann group showed TLW1 transcripts are rapidly induced by wounding in a JA-independent pathway and T-DNA-tagged tlw1 mutants that lack TLW1 transcripts, fail to initiate the full systemic wound response. Transcriptome methodology analysis was set up and transcriptome analyses indicates a two-fold reduced level of JA-responsive but not JA-independent transcripts. The TIR domain of TLW1 was found to interact directly with the KAT2/PED1 gene product responsible for the final b-oxidation steps in peroxisomal-basedJA biosynthesis. To identify potential binding target(s) of TL1 in plant wound response, the CCRC group first expressed recombinant TL1 in bacterial cells and optimized conditions for the protein expression. TL1 was most highly expressed in ArcticExpress cell line. Different types of extraction buffers and extraction methods were used to prepare plant extracts for TL1 binding assay. Optimized condition for glycan labeling was determined, and 2-aminobenzamide was used to label plant extracts. Sensitivity of MALDI and LC-MS using standard glycans. THAP (2,4,6- Trihydroxyacetophenone) showed minimal background peaks at positive mode of MALDI, however, it was insensitive with a minimum detection level of 100 ng. Using LC-MS, sensitivity was highly increased enough to detect 30 pmol concentration. However, patterns of total glycans displayed no significant difference between different extraction conditions when samples were separated with Dionex ICS-2000 ion chromatography system. Transgenic plants over-expressing lectin domains were generated to obtain active lectin domain in plant cells. Insertion of the overexpression construct into the plant genome was confirmed by antibiotic selection and genomic DNA PCR. However, RT-PCR analysis was not able to detect increased level of the transcripts. Binding ability of azelaic acid to recombinant TL1. Azelaic acid was detected in GST-TL1 elution fraction, however, DHB matrix has the same mass in background signals, which needs to be further tested on other matrices. The major findings showed the importance of TLW1 in regulating wound response. The findings demonstrate completely novel and unexpected TIR domain interactions and reveal a control nexus and mechanism that contributes to the propagation of wound responses in Arabidopsis. The implications are to our understanding of the function of TIR domains and to the notion that early molecular events occur systemically within minutes of a plant sustaining a wound. A WEB site (http://genome.weizmann.ac.il/hormonometer/) was set up that enables scientists to interact with a collated plant hormone database.

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