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Mass Chromatogram
A mass chromatogram is a representation of mass spectrometry data as a chromatogram, where the x-axis represents time and the y-axis represents signal intensity. The source data contains mass information; however, it is not graphically represented in a mass chromatogram in favor of visualizing signal intensity versus time. The most common use of this data representation is when mass spectrometry is used in conjunction with some form of chromatography, such as in liquid chromatography–mass spectrometry or gas chromatography–mass spectrometry. In this case, the x-axis represents retention time, analogous to any other chromatogram. The y-axis represents signal intensity or relative signal intensity. There are many different types of metrics that this intensity may represent, depending on what information is extracted from each mass spectrum. Total ion current (TIC) chromatogram The total ion current (TIC) chromatogram represents the summed intensity across the entire range of ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mass Spectrometry
Mass spectrometry (MS) is an analytical technique that is used to measure the mass-to-charge ratio of ions. The results are presented as a '' mass spectrum'', a plot of intensity as a function of the mass-to-charge ratio. Mass spectrometry is used in many different fields and is applied to pure samples as well as complex mixtures. A mass spectrum is a type of plot of the ion signal as a function of the mass-to-charge ratio. These spectra are used to determine the elemental or isotopic signature of a sample, the masses of particles and of molecules, and to elucidate the chemical identity or structure of molecules and other chemical compounds. In a typical MS procedure, a sample, which may be solid, liquid, or gaseous, is ionized, for example by bombarding it with a beam of electrons. This may cause some of the sample's molecules to break up into positively charged fragments or simply become positively charged without fragmenting. These ions (fragments) are then separated acco ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extracted Ion Chromatogram
''Extracted'', also known as ''Extraction'' in the UK, is an independent 2012 American science fiction thriller directed and written by Nir Paniry. Sasha Roiz stars as a scientist whose consciousness becomes trapped in the mind of a convict (Dominic Bogart) who volunteered to be a part of an experimental procedure. Plot Tom, a scientist, invents a machine that can insert a person into the subconscious mind of another person. Desperate for funding to complete his prototype, he is forced to accept money from an anonymous investor. When the investor threatens to pull out, Tom reluctantly agrees to a demonstration a month ahead of schedule. The investor turns out to be an official at the Department of Corrections who wants to use the machine to extract involuntary confessions from convicts. Initially repulsed by the idea, Tom's friend, an entrepreneur, convinces him to proceed, and Tom enters the mind of Anthony, an addict who is suspected of having killed his girlfriend Adrienne. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fragmentation (mass Spectrometry)
In mass spectrometry, fragmentation is the dissociation of energetically unstable molecular ions formed from passing the molecules in the ionization chamber of a mass spectrometer. The fragments of a molecule cause a unique pattern in the mass spectrum. These reactions are well documented over the decades and fragmentation pattern is useful to determine the molar weight and structural information of the unknown molecule. Fragmentation that occurs in tandem mass spectrometry experiments has been a recent focus of research, because this data helps facilitate the identification of molecules. Mass spectrometry techniques Fragmentation can occur in the ion source (in-source fragmentation) where it has been used with electron ionization to help identify molecules and, recently (2020), with electrospray ionization it has been shown to provide the same benefit in facilitating molecular identification. Prior to these experiments, electrospray ionization in-source fragmentation was general ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tandem Mass Spectrometry
Tandem mass spectrometry, also known as MS/MS or MS2, is a technique in instrumental analysis where two or more mass analyzers are coupled together using an additional reaction step to increase their abilities to analyse chemical samples. A common use of tandem MS is the analysis of biomolecules, such as proteins and peptides. The molecules of a given sample are ionized and the first spectrometer (designated MS1) separates these ions by their mass-to-charge ratio (often given as m/z or m/Q). Ions of a particular m/z-ratio coming from MS1 are selected and then made to split into smaller fragment ions, e.g. by collision-induced dissociation, ion-molecule reaction, or photodissociation. These fragments are then introduced into the second mass spectrometer (MS2), which in turn separates the fragments by their m/z-ratio and detects them. The fragmentation step makes it possible to identify and separate ions that have very similar m/z-ratios in regular mass spectrometers. Structu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Selected Reaction Monitoring
Selected reaction monitoring (SRM), also called Multiple reaction monitoring, (MRM), is a method used in tandem mass spectrometry in which an ion of a particular mass is selected in the first stage of a tandem mass spectrometer and an ion product of a fragmentation reaction of the precursor ions is selected in the second mass spectrometer stage for detection. Variants A general case of SRM can be represented by :ABCD^+ \to AB + CD^+ where the precursor ion ABCD+ is selected by the first stage of mass spectrometry (MS1), dissociates into molecule AB and product ion CD+, and the latter is selected by the second stage of mass spectrometry (MS2) and detected. The precursor and product ion pair is called a SRM "transition." Consecutive reaction monitoring (CRM) is the serial application of three or more stages of mass spectrometry to SRM, represented in a simple case by :ABCD^+ \to AB + CD^+ \to C + D^+ where ABCD+ is selected by MS1, dissociates into molecule AB and ion CD+. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Selected Ion Monitoring
Selected ion monitoring (SIM) is a mass spectrometry scanning mode in which only a limited mass-to-charge ratio range is transmitted/detected by the instrument, as opposed to the full spectrum range. This mode of operation typically results in significantly increased sensitivity. Due to their inherent nature, this technique is most effective—and therefore most common—on quadrupole mass spectrometers and Fourier transform ion cyclotron resonance mass spectrometers. See also * Selected reaction monitoring Selected reaction monitoring (SRM), also called Multiple reaction monitoring, (MRM), is a method used in tandem mass spectrometry in which an ion of a particular mass is selected in the first stage of a tandem mass spectrometer and an ion product ... References {{Reflist Mass spectrometry ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Resolution (mass Spectrometry)
In mass spectrometry, resolution is a measure of the ability to distinguish two peaks of slightly different mass-to-charge ratios ''ΔM'', in a mass spectrum. Resolution and resolving power There are two different definitions of resolution and resolving power in mass spectrometry. IUPAC definition The IUPAC definition for resolution in mass spectrometry is :R = \cfrac = \mathrm :\Delta M = \mathrm :M = \mathrm Where a larger resolution indicates a better separation of peaks. This definition is used in a number of mass spectrometry texts. This use is also implied by the term "high-resolution mass spectrometry." A high value for resolution corresponding to good separation of peaks is similar to the convention used with chromatography separations, although it is important to note that the definitions are not the same. High resolution indicating better peak separation is also used in ion mobility spectrometry. Resolving power definition Some mass spectrometrists use the defi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mass Accuracy
Mass spectrometry (MS) is an analytical technique that is used to measure the mass-to-charge ratio of ions. The results are presented as a ''mass spectrum'', a plot of intensity as a function of the mass-to-charge ratio. Mass spectrometry is used in many different fields and is applied to pure samples as well as complex mixtures. A mass spectrum is a type of plot of the ion signal as a function of the mass-to-charge ratio. These spectra are used to determine the elemental or isotopic signature of a sample, the masses of particles and of molecules, and to elucidate the chemical identity or structure of molecules and other chemical compounds. In a typical MS procedure, a sample, which may be solid, liquid, or gaseous, is ionized, for example by bombarding it with a beam of electrons. This may cause some of the sample's molecules to break up into positively charged fragments or simply become positively charged without fragmenting. These ions (fragments) are then separated accordin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromatogram
In chemical analysis, chromatography is a laboratory technique for the separation of a mixture into its components. The mixture is dissolved in a fluid solvent (gas or liquid) called the ''mobile phase'', which carries it through a system (a column, a capillary tube, a plate, or a sheet) on which a material called the ''stationary phase'' is fixed. Because the different constituents of the mixture tend to have different affinities for the stationary phase and are retained for different lengths of time depending on their interactions with its surface sites, the constituents travel at different apparent velocities in the mobile fluid, causing them to separate. The separation is based on the differential partitioning between the mobile and the stationary phases. Subtle differences in a compound's partition coefficient result in differential retention on the stationary phase and thus affect the separation. Chromatography may be preparative or analytical. The purpose of preparativ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Total Ion Current Chromatogram
Total may refer to: Mathematics * Total, the summation of a set of numbers * Total order, a partial order without incomparable pairs * Total relation, which may also mean ** connected relation (a binary relation in which any two elements are comparable). * Total function, a partial function that is also a total relation Business * TotalEnergies, a French petroleum company * Total (cereal), a food brand by General Mills * Total, a brand of strained yogurt made by Fage * Total, a database management system marketed by Cincom Systems * Total Linhas Aéreas - a brazilian airline * Total, a line of dental products by Colgate Music and culture * Total (group), an American R&B girl group * '' Total: From Joy Division to New Order'', a compilation album * ''Total'' (Sebastian album) * ''Total'' (Total album) * ''Total'' (Teenage Bottlerocket album) * ''Total'' (Seigmen album) * ''Total'' (Wanessa album) * ''Total'' (Belinda Peregrín album) * ''Total 1'', an annual compilation al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gas Chromatography–mass Spectrometry
Gas chromatography–mass spectrometry (GC-MS) is an analytical method that combines the features of gas-chromatography and mass spectrometry to identify different substances within a test sample. Applications of GC-MS include drug detection, fire investigation, environmental analysis, explosives investigation, and identification of unknown samples, including that of material samples obtained from planet Mars during probe missions as early as the 1970s. GC-MS can also be used in airport security to detect substances in luggage or on human beings. Additionally, it can identify trace elements in materials that were previously thought to have disintegrated beyond identification. Like liquid chromatography–mass spectrometry, it allows analysis and detection even of tiny amounts of a substance. GC-MS has been regarded as a " gold standard" for forensic substance identification because it is used to perform a 100% specific test, which positively identifies the presence of a partic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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