Signals of diagnostic ions in the product ion spectra of [M − H] − ions of methoxylated flavonoids

2018 ◽  
Vol 33 (1) ◽  
pp. 125-132 ◽  
Author(s):  
Rafał Frański ◽  
Błażej Gierczyk ◽  
Tomasz Kozik ◽  
Łukasz Popenda ◽  
Monika Beszterda
Keyword(s):  
Diagnostic Ions ◽  
Product Ion Spectra

scholarly journals Small Mass but Strong Information: Diagnostic Ions Provide Crucial Clues to Correctly Identify Histone Lysine Modifications

Proteomes ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 18
Author(s):  
Alaa Hseiky ◽  
Marion Crespo ◽  
Sylvie Kieffer-Jaquinod ◽  
François Fenaille ◽  
Delphine Pflieger
Keyword(s):  
Amino Acid ◽  
Small Mass ◽  
Mass Region ◽  
Amino Acid Sequences ◽  
Lysine Modification ◽  
Lysine Residues ◽  
Two Factors ◽  
Low Mass ◽  
Diagnostic Ions

(1) Background: The proteomic analysis of histones constitutes a delicate task due to the combination of two factors: slight variations in the amino acid sequences of variants and the multiplicity of post-translational modifications (PTMs), particularly those occurring on lysine residues. (2) Methods: To dissect the relationship between both aspects, we carefully evaluated PTM identification on lysine 27 from histone H3 (H3K27) and the artefactual chemical modifications that may lead to erroneous PTM determination. H3K27 is a particularly interesting example because it can bear a range of PTMs and it sits nearby residues 29 and 31 that vary between H3 sequence variants. We discuss how the retention times, neutral losses and immonium/diagnostic ions observed in the MS/MS spectra of peptides bearing modified lysines detectable in the low-mass region might help validate the identification of modified sequences. (3) Results: Diagnostic ions carry key information, thereby avoiding potential mis-identifications due to either isobaric PTM combinations or isobaric amino acid-PTM combinations. This also includes cases where chemical formylation or acetylation of peptide N-termini artefactually occurs during sample processing or simply in the timeframe of LC-MS/MS analysis. Finally, in the very subtle case of positional isomers possibly corresponding to a given mass of lysine modification, the immonium and diagnostic ions may allow the identification of the in vivo structure.

Search for Melanoma Markers in Plasma and Serum Samples

2005 ◽  
Vol 11 (3) ◽  
pp. 353-360 ◽  
Author(s):  
Roberta Seraglia ◽  
Susanna Vogliardi ◽  
Graziella Allegri ◽  
Stefano Comai ◽  
Mario Lise ◽  
...  
Keyword(s):  
High Frequency ◽  
Healthy Subjects ◽  
Ionic Species ◽  
Low Molecular Weight ◽  
Ionization Mass ◽  
Plasma Samples ◽  
Serum Samples ◽  
Blood Samples ◽  
Melanoma Patients ◽  
Diagnostic Ions

Fourteen blood samples from patients with melanomas and 11 blood samples from healthy subjects were analyzed by matrix-assisted laser desorption/ionization mass spectrometry. The study focussed on species of low molecular weight, in the 800–5000 Da range, present in plasma and sera. While for healthy subjects plasma samples lead to the production of a higher number of ionic species, for melanoma patients a high number of diagnostic ions, present with high frequency and with quite high relative abundance, are present, in particular, in serum samples and, to a lesser extent, also in plasma. Since plasma samples are obtained more easily in comparison to sera, it is possible to suggest that plasma can also be used for these studies.

Analytical Strategy for the Regulatory Control of Residues of Chloramphenicol in Meat: Preliminary Studies in Milk

1992 ◽  
Vol 75 (2) ◽  
pp. 245-256 ◽  
Author(s):  
H J Keukens ◽  
M M L Aerts ◽  
W A Traag ◽  
J F M Nouws ◽  
W G De Ruig ◽  
...  
Keyword(s):  
Limit Of Detection ◽  
Collaborative Study ◽  
Regulatory Control ◽  
Veterinary Drug ◽  
Uv Spectrum ◽  
Analytical Strategy ◽  
Column Liquid Chromatographic ◽  
Set Up ◽  
Diagnostic Ions ◽  
Liquid Chromatographic

Abstract An analytical strategy Is described for the regulatory control of residues of the veterinary drug chloramphenicol (CAP) In meat. Screening is performed directly in meat by a simple immunochemical card test with a limit of detection of about 2 μg/kg. Statistical evaluation of a collaborative study involving 13 laboratories showed that at CAP concentrations exceeding 8 μg/kg, no false negatives are found (N = 554). In positive samples, CAP Is quantltated with a routinely applicable, collaboratively tested column liquid chromatographic method with a limit of detection of about 1 μg/kg. At concentrations exceeding 10 μg/kg, the Identity of CAP Is established by Its UV spectrum obtained by using diode-array UV/VIS detection. A further confirmation can be obtained by the combination of gas chromatography/ mass selective detection In the electron Impact mode. Using 2 diagnostic Ions (m/z 225 and 208), the limit of identification Is about 5 μg/kg. The combination of the different analytical principles ensures reliable quantitation and Identification of CAP in positive samples, as established experimentally in Incurred samples and spiked samples (n > 100), and theoretically by the estimation of the uncertainty factor. The proposed set-up makes a regulatory program possible in which screening can be performed In a simple laboratory environment, followed by quantitation and Identification under more sophisticated conditions. Preliminary experiments Indicate that the analytical strategy Is also applicable to the control of CAP in milk. Application of mass spectrometry with negative chemical ionization permits the confirmation of CAP concentrations as low as 0.2 μg/L.

scholarly journals Development and application of a forensic toxicological library for identification of 56 natural toxic substances by liquid chromatography–quadrupole time-of-flight mass spectrometry

2019 ◽  
Vol 38 (1) ◽  
pp. 232-242 ◽  
Author(s):  
Tadashi Ogawa ◽  
Kei Zaitsu ◽  
Tetsuo Kokaji ◽  
Kayako Suga ◽  
Fumio Kondo ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Time Of Flight ◽  
Human Blood Plasma ◽  
Toxic Substances ◽  
Flight Mass Spectrometry ◽  
Death Case ◽  
Postmortem Blood ◽  
Negative Ionization ◽  
Product Ion Spectra

Abstract Purpose The present study aims to develop a forensic toxicological library to identify 56 natural toxic substances by liquid chromatography–quadrupole time-of-flight tandem mass spectrometry (LC–QTOF-MS/MS). Methods For setting up the library of product ion spectra, individual substances (31 plant toxins, 7 mushroom toxins, 5 marine toxins, 5 frog venoms, 4 mycotoxins, and 4 substances derived from plants) were analyzed by LC–QTOF-MS/MS with positive and negative ionization. The product ion spectra were acquired at the collision energies (CEs) of 20, 35, and 50 eV in single enhanced product ion mode and then in collision energy spread mode in which the CE ramp range was set to 35 ± 15 eV. Results To test the performance of the library, human blood plasma samples were spiked with a mixture of lycorine and domoic acid, extracted by acetonitrile deproteinization and analyzed by LC–QTOF-MS/MS. Identification by our library search could be achieved for these toxins at the purity scores of 79.1 and 67.2, respectively. The method was also applied to postmortem blood from a death case with an aconite intake, and showed that four toxins in an aconite could be identified in the blood sample at the purity scores of 54.6–60.3. Conclusions This library will be more effective for the screening of natural toxic substances in routine forensic toxicological analysis. To our knowledge, there are no reports dealing with development of library for natural toxic substances by LC–QTOF-MS/MS.

Probabilistic model applied to ion abundances in product-ion spectra: quantitative analysis of aspartic acid isomerization in peptides

2019 ◽  
Vol 411 (29) ◽  
pp. 7783-7789 ◽  
Author(s):  
Daniil G. Ivanov ◽  
Maria I. Indeykina ◽  
Stanislav I. Pekov ◽  
Adel E. Iusupov ◽  
Anna E. Bugrova ◽  
...  
Keyword(s):  
Quantitative Analysis ◽  
Aspartic Acid ◽  
Probabilistic Model ◽  
Acid Isomerization ◽  
Product Ion Spectra

Unexpected cytosine–AuCl4− interaction under electrospray ionization mass spectrometry conditions—Formation of cytosine–Au(I) complexes

2019 ◽  
Vol 26 (3) ◽  
pp. 225-229
Author(s):  
Magdalena Frańska ◽  
Emilia Konował
Keyword(s):  
Electrospray Ionization ◽  
Gas Phase ◽  
Mass Spectra ◽  
Mass Spectrometric ◽  
Negative Ion ◽  
Ionization Mass ◽  
Ionization Source ◽  
Full Scan ◽  
Negative Ion Mode ◽  
Product Ion Spectra

The interaction of cytosine with AuCl4−, under electrospray ionization mass spectrometric conditions, is discussed. On the basis of respective full scan mass spectra and product ion spectra, obtained in positive and negative ion mode, it has been deduced that cytosine is very prone to form Au(I)-containing complexes. The complexes may be formed in the gas phase by decomposition of Au(III)-containing complexes and also in the electrospray ionization source as a result of the occurrence of redox process. It has also been found that the interaction of cytosine with Au+ is stronger than that with Cu+ or Ag+, although taking into account the electrostatic attraction, it is not expected.

scholarly journals Identification and signature profiles for pro-resolving and inflammatory lipid mediators in human tissue

2014 ◽  
Vol 307 (1) ◽  
pp. C39-C54 ◽  
Author(s):  
Romain A. Colas ◽  
Masakazu Shinohara ◽  
Jesmond Dalli ◽  
Nan Chiang ◽  
Charles N. Serhan
Keyword(s):  
Human Peripheral Blood ◽  
Principal Component ◽  
Chromatographic Behavior ◽  
Lipid Mediator ◽  
General Interest ◽  
Lymphoid Tissues ◽  
Biosynthetic Pathways ◽  
Omega 3 ◽  
Peripheral Blood Plasma ◽  
Diagnostic Ions

Resolution of acute inflammation is an active process locally controlled by a novel genus of specialized pro-resolving mediators (SPM) that orchestrate key resolution responses. Hence, it is of general interest to identify individual bioactive mediators and profile their biosynthetic pathways with related isomers as well as their relation(s) to classic eicosanoids in mammalian tissues. Lipid mediator (LM)-SPM levels and signature profiles of their biosynthetic pathways were investigated using liquid chromatography-tandem mass spectrometry (LC-MS-MS)-based LM metabololipidomics. LM and SPM were identified using ≥6 diagnostic ions and chromatographic behavior matching with both authentic and synthetic materials. This approach was validated using the composite reference plasma (SRM1950) of 100 healthy individuals. Using targeted LM metabololipidomics, we profiled LM and SPM pathways in human peripheral blood (plasma and serum) and lymphoid organs. In these, we identified endogenous SPM metabolomes, namely, the potent lipoxins (LX), resolvins (Rv), protectins (PD), and maresins (MaR). These included RvD1, RvD2, RvD3, MaR1, and NPD1/PD1, which were identified in amounts within their bioactive ranges. In plasma and serum, principal component analysis (PCA) identified signature profiles of eicosanoids and SPM clusters. Plasma-SPM increased with omega-3 and acetylsalicylic acid intake that correlated with increased phagocytosis of Escherichia coli in whole blood. These findings demonstrate an approach for identification of SPM pathways (e.g., resolvins, protectins, and maresins) in human blood and lymphoid tissues that were in amounts commensurate with their pro-resolving, organ protective, and tissue regeneration functions. LM metabololipidomics coupled with calibration tissues and physiological changes documented herein provide a tool for functional phenotypic profiling.

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