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Sampling and Laboratory Analysis for Solvent Stabilizers
Published in Thomas K.G. Mohr, William H. DiGuiseppi, Janet K. Anderson, James W. Hatton, Jeremy Bishop, Barrie Selcoe, William B. Kappleman, Environmental Investigation and Remediation, 2020
Thomas K.G. Mohr, Jeremy Bishop
A mass spectrometer is a detector used in GC. Mass spectrometers ionize gaseous molecules, separate the ions produced on the basis of the m/z, and then record the relative number of different ions produced. The m/z ratio is then plotted as the abscissa with relative intensity as the ordinate. This plot is referred to as a “mass spectrum.” The mass spectrum of a compound can be considered its “fingerprint” and can be used to identify a compound through comparison with published reference spectra. MS systems interface with computers that compare experimental spectra to standard spectra and perform the identification automatically. Spectra that do not match calibration standard spectra can be compared with a library of spectra, and a tentative identification can be made.
Biophysical and Biochemical Characterization of Peptide, Protein, and Bioconjugate Products
Published in Sandeep Nema, John D. Ludwig, Parenteral Medications, 2019
Tapan K. Das, James A. Carroll
Tandem mass spectrometry (MS/MS), in which an ion formed in the ionization source is subjected to fragmentation, followed by mass measurement of the resulting fragment ions, is a powerful tool for determining the precise sites of modifications, down to the specific amino acid residue. MS/MS can be accomplished using several different modes of fragmentation. Most commonly used is CAD (also known as “collision-induced dissociation”, or CID), in which the precursor ion is accelerated in a collision cell in the mass spectrometer which is filled with a gas, such as argon, to impart internal energy into the ion, leading to fragmentation. For peptides, fragmentation tends to occur along the peptide backbone at the amide bonds. This leads to fragment ion spectra which differ in mass by the residue mass of the amino acids present in the peptide. In this way, the sequence of the peptide and the sites of modifications to the peptide can be determined. Fragmentation of the peptide can also be generated using other means, including electron transfer dissociation in ion trap or Orbitrap instruments, or electron capture dissociation or multiphoton dissociation in ion cyclotron resonance instruments. These alternate modes of fragmentation may provide complementary information to CAD, such that in combination increased structural information may be obtained.
Emerging Biomedical Analysis
Published in Lawrence S. Chan, William C. Tang, Engineering-Medicine, 2019
Tandem mass spectrometry (MS/MS or MS2) refers to the combination of two or more mass analyzers in a single mass spectrometer. In a tandem mass spectrometer, ions in a wide mass range are first measured in the first stage of mass spectrometry (MS1); based on the MS1 data, ions within a narrow mass range (precursor ions) are isolated and dissociated; the fragment or product ions are then identified in the second stage of mass spectrometry (MS2). This concept can be extended to multi-stage mass spectrometry (MSn) if the product ions are further isolated, fragmented and measured in the nth stage of mass spectrometry (MSn).
Methods of Metabolite Identification Using MS/MS Data
Published in Journal of Computer Information Systems, 2022
Myungjae Kwak, Kyungwoo Kang, Yingfeng Wang
Over the last few decades, mass spectrometry technology has been widely applied in metabolomics because the MS/MS spectra data contains ample substructure information of the metabolites.30 Metabolite identification based on tandem mass spectrometry (MS/MS) data provides a means to analyze metabolic activities. However, accurate identification of metabolites from MS/MS data has been a significant challenge in the field. To develop reliable computational and software tools for metabolite identification, researchers have been investigating fragmentation rules in MS/MS fragmentation, which separates a metabolite into small fragments by breaking some chemical bonds. Among various chromatography technologies, liquid chromatography coupled with electrospray ionization–mass spectrometry (LC-MS) has become a method of choice for profiling metabolites in complex biological samples. This is because LC-MS can effectively ionize a breath of metabolites with minimal fragmentation, compared to gas chromatography-mass spectroscopy (GC-MS).4,31 Also, it can scale-up to support tandem mass spectrometry-based structural studies (versus capillary electrophoresis-mass spectrometry (CE-MS)).4,31Figure 1 shows workflow of conventional liquid chromatography–tandem mass spectrometry, which includes sample preparation, liquid chromatography, MS/MS profiling, and data analysis steps.
Indicator dye based screening of glutaminase free L-asparaginase producer and kinetic evaluation of enzyme production process
Published in Preparative Biochemistry & Biotechnology, 2020
Pragya Prakash, Hare Ram Singh, Santosh Kumar Jha
Mass spectrometry is a technique used for the identification of proteins in pure sample based upon molecular weight.[34] However, this technique is also useful in the identification of protein in complex mixtures. Analytical techniques such as HPLC may prove beneficial for the detection of proteins, but the actual molecular weight analysis is done using Mass spectroscopy.[30] The analysis comprises molecular weight identification of initial and final products of enzymatic reactions, which are usually amino acids.[31] In this work, L-asparaginase activity was characterized by the formation of aspartic acid as a final product in the case of L-asparaginase activity; also Glutaminase activity was characterized by identification of glutamic acid as a final product in the reaction mixture.[32] The concentration of L-aspartic acid and L-glutamine was denoted by peaks height corresponding to concentrations of amino acids. It can be easily depicted from the figure (Fig. 4), the molecular weight of 133.0 represents aspartic acid relative concentration with standard of the corresponding amino acid; also, the mass peak of 147.0 indicates the presence of glutamine, thereby indicating the presence of no glutaminase activity along with asparaginase activity (Fig. 4). However, as mention, the focus of the current report was to achieve significant asparaginase activity with no glutaminase activity.
An overview of the current progress, challenges, and prospects of human biomonitoring and exposome studies
Published in Journal of Toxicology and Environmental Health, Part B, 2019
Mariana Zuccherato Bocato, João Paulo Bianchi Ximenez, Christian Hoffmann, Fernando Barbosa
In the last 10 years, there have been extensive investigations in proteomics using high-resolution mass spectrometers such as MALDI-MS or ESI-TOF-MS and some database software with established peptide sequence. It became possible to identify the positions of any modifications within a series of peptides and with information on the entire protein sequence defining the sites of the change in the protein itself (Becker and Bern 2011). Currently, investigators working in this area are seeking to answer two fundamental questions: what are the targets of reactive intermediates? what are the outcomes related to protein modification? The elucidation of these questions might solve many problems in contemporary research. This ability to establish relationships between the endpoints and protein markers enables the detection of unique protein profiles (Geyer et al. 2017).