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Targeted proteomic approaches in the context of COVID-19 pandemic
Published in Sanjeeva Srivastava, Multi-Pronged Omics Technologies to Understand COVID-19, 2022
Mehar Un Nissa, Alisha Srivastava, Medha Gayathri J. Pai
It can be unarguably said that the field of mass spectrometry–based targeted proteomics has been possible because of the pioneering work on the workhorse Triple Quadrupole. As the name suggests, a Triple Quadrupole (TQ) mass spectrometer has three quadrupoles; the first and third quadrupoles act as “mass filters” while the second one acts as a collision cell. We refer to the quadrupoles as “mass filters” as they can allow ions having specific m/z values to pass through, hence in a sense “filtering the ions”.
Emerging Biomedical Analysis
Published in Lawrence S. Chan, William C. Tang, Engineering-Medicine, 2019
Q-TOFMS and Q-OTMS are operated with similar principles. The quadrupole can be used as a path to transfer all of the ions or as a mass filter to select specific ions. The TOF or Orbitrap serves as a high-resolution mass analyzer for accurate mass measurement. In these types of instruments, data-dependent acquisition (DDA) and data-independent acquisition (DIA) are the two commonly used acquisition modes. In DDA mode, a high-resolution survey scan of all precursor ions is first acquired in the TOF or Orbitrap. Several MS/MS scans of the selected ions are then acquired based on the survey scan according to a certain rule, typically on ions exhibiting the highest intensities in the survey scan. DDA allows the data acquisition of certain ions without any information prior to the analysis. It is very useful for large-scale unknown sample analysis when combined with front-end separation techniques, such as HPLC or CE. DIA involves data acquisition within a predefined mass range. SRM is one of the DIA strategies used for quantitatively measuring samples with known information. Other DIA strategies, such as MSE and sequential window acquisition of all theoretical fragment ion spectra (SWATHTM), can be applied to analyze large-scale protein mixtures.
Transverse Beam Optics
Published in Volker Ziemann, ®, 2019
In this section we address several of the often-used beam-optical modules. One example, we encountered before, the FODO-cell, is a module that is frequently used to cover long distances with a simple magnet lattice. The arcs of the LHC consist of FODO-cells with additional dipole magnets to force the particles on their circular path along the 27 km long beam pipe. Quadrupoles are used to focus deviating particles back towards their design orbit and thereby ensure stable operation. While the FODO-cells serve to transport the beam through the approximately 3km long octants, the beams need to be focused to extremely small sizes inside the detectors, such as ATLAS and CMS, that are located in straight sections between the octants. In order to demagnify the beams to sizes of tens of microns, other optical modules are used, in this special case the telescopes, we consider next.
Interaction of Cesium Hydroxide with Oxide Layers Under Simulated Light Water Reactor Severe Accident
Published in Nuclear Science and Engineering, 2023
I Wayan Ngarayana, Kenta Murakami, Anis Rohanda, Tatsuya Suzuki
A TG-DTA 2000SA/MS 9610 machine from Bruker was used to examine temperature-related mass changes, which are strongly related to some physicochemical phenomena, i.e., evaporation, chemical reaction, decomposition, dehydration, etc. This machine was run in an air environment ranging from RT to 1050°C with a temperature change rate of 5°C/min. The machine includes quadrupole mass spectroscopy that utilizes electron ionization, which is a “hard” ionization technique that creates mostly singly charged positive ions. The quadrupole mass spectroscopy uses four parallel metal rods to create an electric field that filters ions based on their mass-to-charge ratio. The electric field acts as a filter, allowing only ions with a specific mass-to-charge ratio to pass through the rods and reach the detector. Different ions can be chosen and measured by varying the voltage and frequency of the electric field.
Pyrolysis behaviors and product distribution of Shengli Lignite at different heating rate and final temperature by TG-FTIR and Py-GC-MS
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2021
Zhenyong Miao, Yongjiang Wan, Qiongqiong He, Zhen Pei, Xiaoqian Zhu
The Py-GC-MS system mainly included a Pyroprobe 5000 series, a GC (PerkinElmer Clarus 680) and an MS (PerkinElmer Clarus SQ 8 T). A special transmission pipeline interface was used to connect the Py to the GC-MS. A constant helium (99.999%) flow rate of 31.5 mL/min was employed as a carrier gas with a spilled ratio of 1:30. The pyrolysis initiation temperature was held at 50°C for 1 min, and then the temperature was raised from 50°C to 400°C, 600°C, and 800°C (held for 5 s) at heating rates of 20°C/min and 100°C/min. The temperature of the GC oven ramp was held at 50°C for 1 min, then increased from 50°C to 200°C at a rate of 6°C/min and held for 3 min, and finally increased at a rate of 6°C/min from 200°C to 300°C and again held for 3 min. Then, the pyrolysis products were introduced into the gas chromatograph for separation. MS was mainly composed of an ion source, mass analyzer, and detector components. The ionization source was in the EI mode (using Marathon filament) set to 70 eV ionizing energy. The gasified sample was introduced into the mass spectrometer through the transmission line, broken into the gaseous ions by the ion source, and then separated and analyzed. The mass analyzer measured fragments in a scanning range from 50 to 600 m/z (m is the number of molecules or atomic mass, z is the charge of the ion). The quadrupole analyzer separated the gaseous ions by their mass-to-charge ratio. The fragment ions from the quadrupole analyzer were first passed through a grounded ion inlet plate and then passed into the ion optics to filter out a portion of the charged interfering ions. Then, the charged ions pass through the 270° deflection power plant to the lift level. Finally, the electrons displaced from the pickup level fly back to the electron multiplier tube and were amplified step-by-step and detected through the electron multiplier tube. The spectral library could be used to determine the molecular weight, molecular formula and structural formula of the products. Then, it provided semiquantitative analysis of the various compounds through the system software according to the relative size of the peak area.