scholarly journals Studies on Positive and Negative ionization mode of ESI-LC-MS/ MS for screening of Phytochemicals on Cassia auriculata (Aavaram Poo)

2018 ◽  
Vol 10 (3) ◽  
pp. 457-462
Author(s):  
Paranthaman Ramakrishnan ◽  
Sureshkumar Kalakandan ◽  
Muthukumaran Pakkirisamy
Keyword(s):  
Cassia Auriculata ◽  
Negative Ionization Mode ◽  
Ionization Mode ◽  
Negative Ionization

scholarly journals Improved Small Molecule Identification through Learning Combinations of Kernel Regression Models

Metabolites ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 160 ◽  
Author(s):  
Céline Brouard ◽  
Antoine Bassé ◽  
Florence d’Alché-Buc ◽  
Juho Rousu
Keyword(s):  
Small Molecule ◽  
Kernel Regression ◽  
Feature Space ◽  
Molecular Structures ◽  
Subgradient Optimization ◽  
Hinge Loss ◽  
Fast Training ◽  
Negative Ionization Mode ◽  
Ionization Mode ◽  
Negative Ionization

In small molecule identification from tandem mass (MS/MS) spectra, input–output kernel regression (IOKR) currently provides the state-of-the-art combination of fast training and prediction and high identification rates. The IOKR approach can be simply understood as predicting a fingerprint vector from the MS/MS spectrum of the unknown molecule, and solving a pre-image problem to find the molecule with the most similar fingerprint. In this paper, we bring forward the following improvements to the IOKR framework: firstly, we formulate the IOKRreverse model that can be understood as mapping molecular structures into the MS/MS feature space and solving a pre-image problem to find the molecule whose predicted spectrum is the closest to the input MS/MS spectrum. Secondly, we introduce an approach to combine several IOKR and IOKRreverse models computed from different input and output kernels, called IOKRfusion. The method is based on minimizing structured Hinge loss of the combined model using a mini-batch stochastic subgradient optimization. Our experiments show a consistent improvement of top-k accuracy both in positive and negative ionization mode data.

Rapid determination of canagliflozin in rat plasma by UHPLC–MS/MS using negative ionization mode to avoid adduct-ions formation

Talanta ◽  
2015 ◽  
Vol 132 ◽  
pp. 29-36 ◽  
Author(s):  
Muzaffar Iqbal ◽  
Essam Ezzeldin ◽  
Khalid A. Al-Rashood ◽  
Yousif A. Asiri ◽  
Naser L. Rezk
Keyword(s):  
Rapid Determination ◽  
Rat Plasma ◽  
Negative Ionization Mode ◽  
Ionization Mode ◽  
Negative Ionization

Validated Chiral LC-ESI-MS/MS Method for the Simultaneous Quantification of Darolutamide Diastereomers and Its Active Metabolite in Mice Plasma: Application to a Pharmacokinetic Study

Drug Research ◽  
2018 ◽  
Vol 68 (11) ◽  
pp. 615-624
Author(s):  
Narayan Balaji ◽  
Suresh Sulochana ◽  
Neeraj Saini ◽  
Siva A. ◽  
Ramesh Mullangi
Keyword(s):  
Pharmacokinetic Study ◽  
Active Metabolite ◽  
Multiple Reaction Monitoring ◽  
Internal Standard ◽  
Triple Quadrupole Mass Spectrometer ◽  
Liquid Liquid Extraction ◽  
Regulatory Guidelines ◽  
Negative Ionization Mode ◽  
Ionization Mode ◽  
Negative Ionization

AbstractA simple, selective and reliable LC-MS/MS method was developed and validated for the simultaneous quantitation of darolutamide diastereomers (diastereomer-1 and diastereomer-2) and its active metabolite i. e. ORM-15341 in mice plasma using warfarin as an internal standard (IS) as per the regulatory guidelines. Plasma samples were extracted by liquid-liquid extraction and the chromatographic separation was achieved on a Chiralpak IA column with an isocratic mobile phase 5 mM ammonium acetate:absolute alcohol (20:80, v/v) at a flow rate of 1.0 mL/min. Detection and quantitation was done by multiple reaction monitoring on a triple quadrupole mass spectrometer following the transitions: m/z 397→202, 395→202 and 307→250 for darolutamide diastereomers, ORM-15341 and the IS, respectively in the negative ionization mode. The calibration curves were linear (r>0.992) in the range of 100–2400 ng/mL for all the analytes. The intra- and inter-day precisions were in the range of 1.25–10.2 and 1.58-12.3; 2.85-5.68 and 1.85-9.58; 2.34-12.1 and 2.58-7.38 for diastereomer-1, diastereomer-2 and ORM-15341, respectively. Both diastereomers and ORM-15341 were found to be stable under different stability conditions. The validated method was applied to a pharmacokinetic study in mice.

5,6-Epoxyeicosatrienoic Acid Mediates the Enhanced Renal Vasodilator Response to Arachidonic Acid (AA) in the SHR.

Hypertension ◽  
2000 ◽  
Vol 36 (suppl_1) ◽  
pp. 713-713
Author(s):  
Silvia I Pomposiello ◽  
Mairead A Carroll ◽  
John C McGiff
Keyword(s):  
Arachidonic Acid ◽  
The Other ◽  
Epoxyeicosatrienoic Acid ◽  
Wky Rats ◽  
Vasodilator Response ◽  
Negative Ionization Mode ◽  
Selective Ion Monitoring ◽  
Ionization Mode ◽  
Negative Ionization ◽  
Renal Vascular

P109 The cytochrome P450-dependent renal vasodilator effect of arachidonic acid (AA) that is expressed when cyclooxygenase is inhibited and perfusion pressure (PP) is elevated, is enhanced in SHR. In kidneys perfused with Krebs’ solution and preconstricted with phenylephrine to increase PP to ca 200 mmHg, 5 μg of AA reduced PP by 92 ± 10 mmHg in SHR compared to 44.5 ± 5 mmHg for WKY rats. In contrast, the dilator effects of acetylcholine (Ach; 0.1 μg) or sodium nitroprusside (SNP; 1 μg) were not different. As the response to AA was inhibited by ETYA (4 μM), an inhibitor of all AA oxygenase pathways, and also inhibited by the selective epoxygenase inhibitors, miconazole (0.3 μM) and MSPPOH (12 μM), we concluded that the vasodilator mediator(s) of the AA response was most likely an epoxyeicosatrienoic acid (EET). We therefore, assessed the renal vascular responses to EETs in the SHR and WKY. We found that 5,6-EET, 8,9-EET, and 11,12-EET were dilators in both SHR and WKY, whereas 14,15-EET produced constriction. 5,6-EET was the most potent dilator of the EET regioisomers in the SHR resulting in a decrease in PP of 56 ± 5 mmHg compared to 12 ± 4 mmHg for 8,9-EET and 15 ± 4 mmHg for 11,12-EET. The decrease in PP elicited by 5 μg of 5,6-EET was greater in SHR, 56 ± 5 mmHg compared to 29 ± 4 mmHg for WKY rats whereas the responses to the other EET regioisomers did not differ. We measured the release of EETs from SHR and WKY kidneys in response to 5 μg of AA, by GC-MS in negative ionization mode using selective ion monitoring. The release of 5,6-EET was increased in SHR (from a basal level of 0.5 ± 0.04 to 0.9 ± 0.1 ng/min; P<0.05) compared to WKY (from a basal level of 0.6 ± 0.2 to 0.7 ± 0.2 ng/min), whereas the release of the other EETs were not different. We suggest that 5,6-EET is the most likely mediator of the AA response and that the augmented vasodilator response to AA in the SHR kidney might be linked to increased production of and responsiveness to 5,6-EET.

scholarly journals Untargeted Metabolomic Profiling of Early Diet Energy Intake in C57BL/6 N Mice Reveals Differences Associated with Diet and Aberrant Crypt Foci

2020 ◽  
Vol 4 (Supplement_2) ◽  
pp. 1249-1249
Author(s):  
Haley Chatelaine ◽  
Spencer Kyle ◽  
Cynthia Ramazani ◽  
Susan Olivo-Marston ◽  
Emmanuel Hatzakis ◽  
...  
Keyword(s):  
High Performance ◽  
Linear Models ◽  
High Resolution Mass Spectrometry ◽  
Control Diet ◽  
Aberrant Crypt Foci ◽  
Funding Sources ◽  
Negative Ionization Mode ◽  
Ionization Mode ◽  
Negative Ionization ◽  
Polar Extracts

Abstract Objectives A high-fat (H) diet leads to obesity, a known risk factor for colorectal cancer (CRC). In contrast, calorie restriction (E) is associated with reduced CRC risk. However, the metabolome associated with H vs. E-associated CRC risk has never been directly compared. The different influences of these diets on the proximal (PC), medial (MC), and distal (DC) colon metabolome has also not been studied. Thus, the objective is to elucidate metabolites associated with abberant crypt foci (ACF) number, a marker of CRC risk, in each colon region after consumption of H, E, or a normocaloric control diet (C). Methods 3-week-old C57BL/6 N mice were fed a C, E, or H initiation diet for 13 weeks. In weeks 16–21, animals were injected with azoxymethane to initiate ACF formation, and switched to a C, E, or H progression diet (for a total of 9 diet groups: CC, CH, CE, HH, HC, HE, EE, EC, EH). Polar extracts of the colon regions (i.e., PC, MC, and DC) were analyzed using ultra-high performance liquid chromatography-high resolution mass spectrometry method (HRMS) and 1H NMR metabolomics methods. Linear models assessed the main effects of ACF, initiation diet, progression diet, as well as the diet * ACF interaction, on relative metabolite concentration in each colon region. Results Following HILIC-HRMS analysis of extracts in positive and negative ionization mode, 492 and 415 metabolites were detected, respectively. Linear models revealed 21 metabolites were significantly associated with initiation E diet * ACF (8 unique to MC, 13 unique to PC), 14 with initiation H diet * ACF (only in DC), 27 with progression H diet * ACF (14 unique to DC, 2 to MC, 11 to PC) and 20 with progression E diet * ACF (17 unique to DC, 1 to PC, and 1 common to both). Pathway integration and authentication of tentative metabolite identities with chemical standards is underway. Conclusions Diet * ACF interaction significantly influences multiple metabolite concentrations. Little to no overlap is observed between metabolites associated with ACF in a given colon region and the other regions tested, revealing that the diet * ACF interaction is region-specific. Future studies in humans will determine if these metabolites may serve as early biomarkers for CRC diagnosis. Funding Sources Sample analyses were supported by NIH Award Number Grant P30 CA016058, OSU, and OSUCCC.

scholarly journals A study on electrospray mass spectrometry of fullerenol C60(OH)24

2013 ◽  
Vol 9 ◽  
pp. 1285-1295 ◽  
Author(s):  
Mihaela Silion ◽  
Andrei Dascalu ◽  
Mariana Pinteala ◽  
Bogdan C Simionescu ◽  
Cezar Ungurenasu
Keyword(s):  
Full Characterization ◽  
Signal Stability ◽  
Multiply Charged ◽  
Negative Ionization Mode ◽  
Positive Mode ◽  
Ionization Mode ◽  
Negative Ionization ◽  
Good Signal ◽  
Capillary Voltage

Full characterization of fullerenol C60(OH)24 by HPLC ESI-MS in negative and positive ionization modes was achieved. Fragmentor voltage and capillary voltage were optimized in order to obtain a good signal stability and the best peak intensity distribution for the fullerenol C60(OH)24 in both negative and positive modes. While the predominant base peak observed for C60(OH)24 in the negative ionization mode was [M − H]− at m/z 1127, those observed in the positive mode were multiply charged [M − H2O + 4H]4+ at m/z 279 and [M − 12H2O + 2NH3 + 6H]6+ at m/z 158.

Simultaneous Determination of 44 Pesticides in Tobacco by UPLC/MS/MS and a Modified QuEChERS Procedure

2013 ◽  
Vol 96 (2) ◽  
pp. 422-431 ◽  
Author(s):  
Xuyan Chen ◽  
Kongxiang Zhao ◽  
Baokun Ge ◽  
Qiyong Chen
Keyword(s):  
Multiple Reaction Monitoring ◽  
Graphitized Carbon Black ◽  
Modified Quechers ◽  
Negative Ionization Mode ◽  
Multiple Reaction Monitoring Mode ◽  
Primary Secondary Amine ◽  
Standard Calibration ◽  
Ionization Mode ◽  
Negative Ionization

Abstract A novel, simple, and rapid method for determination of the residues of 44 commonly used pesticides in tobacco was developed based on modified Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) procedures. The pesticides were extracted with acetonitrile and purified on a mixed sorbents column of primary secondary amine, C18, and graphitized carbon black. Quantitative determination of all pesticides was performed by ultra-performance LC/MS/MS in the positive or negative ionization mode by a single run due to the fast polarity switching capability of the mass spectrometer. Two precursor-product ion transitions were monitored for each compound in the multiple reaction monitoring mode. Quantification was carried out using matrix-matched standard calibration. The method has been validated by various tobacco cultivars, such as Burley, Oriental, and Virginia from different countries. Recoveries of the proposed method for spiked samples ranged from 71.1 to 109.8%, and RSD values were below 10%. The LOQ values were are all below the guidance residue levels proposed by the Agrochemical Advisory Committee of Cooperation Center for Scientific Research Relative to Tobacco. This method is valuable for measurement of pesticide residues in tobacco for QC and monitoring.

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