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Encyclopedia > Mass spectrometry

Mass spectrometry (previously called mass spectroscopy (deprecated) or informally, "mass-spec" and MS) is an analytical technique that measures the mass-to-charge ratio of ions.[1] It is most generally used to find the composition of a physical sample by generating a mass spectrum representing the masses of sample components. The mass spectrum is measured by a mass spectrometer. Image File history File links No higher resolution available. ... It has been suggested that Charge-to-mass ratio be merged into this article or section. ... This article is about the electrically charged particle. ... A mass spectrum is an intensity vs. ...

All mass spectrometers consist of three basic parts: an ion source, a mass analyzer, and a detector system. The stages within the mass spectrometer are: An ion source is an electro-magnetic device that is used to create charged particles. ...

1. Production of ions from the sample
2. Separation of ions with different masses
3. Detection of the number of ions of each mass produced
4. Collection of data to generate the mass spectrum

The technique has several applications, including:

• identifying unknown compounds by the mass of the compound molecules or their fragments
• determining the isotopic composition of elements in a compound
• determining the structure of a compound by observing its fragmentation
• quantifying the amount of a compound in a sample using carefully designed methods (mass spectrometry is not inherently quantitative)
• studying the fundamentals of gas phase ion chemistry (the chemistry of ions and neutrals in vacuum)
• determining other physical, chemical, or even biological properties of compounds with a variety of other approaches

Look up chemical compound in Wiktionary, the free dictionary. ... For other uses, see Isotope (disambiguation). ... This article does not cite any references or sources. ... ...

For more details on this topic, see History of mass spectrometry.
Francis William Aston won the 1922 Nobel Prize in Chemistry for his work in mass spectrometry

In 2002, the Nobel Prize in Chemistry was received by John Bennett Fenn for the development of electrospray ionization (ESI) and Koichi Tanaka for the development of soft laser desorption (SLD) in 1987. An improved SLD method, matrix-assisted laser desorption/ionization (MALDI), was developed in 1987 by Franz Hillenkamp and Michael Karas.[2] Also see: 2002 (number). ... This is a list of Nobel Prize laureates in Chemistry from 1901 to 2006. ... Electrospray (nanoSpray) ionization source Electrospray ionization (ESI) is a technique used in mass spectrometry to produce ions. ... Koichi Tanaka (ç”°ä¸­ è€•ä¸€, born August 3, 1959) is a Japanese scientist who won the Nobel Prize in Chemistry in 2002 for developing a novel method for mass spectrometric analyses of biological macromolecules. ... Soft laser desorption is laser desorption of large molecules that results in ionization without fragmentation. ... Year 1987 (MCMLXXXVII) was a common year starting on Thursday (link displays 1987 Gregorian calendar). ... MALDI TOF mass spectrometer Matrix-assisted laser desorption/ionization (MALDI) is a soft ionization technique used in mass spectrometry, allowing the analysis of biomolecules (biopolymers such as proteins, peptides and sugars) and large organic molecules (such as polymers, dendrimers and other macromolecules), which tend to be fragile and fragment when...

## Simplified working example

Schematics of a typical mass spectrometer

This example was of a sector instrument, however there are many types of mass spectrometers. All of these have in common that they possess an Ion Source, that produces ions, an Analyzer that sorts them in some way by their masses, and a Detector that measures the relative intensities of different masses. The underlying principle of all mass spectrometers is that the paths of gas phase ions in electric and magnetic fields are dependent on their mass-to-charge ratios which is used by the analyzer to distinguish the ions from one another. A sector instrument is a general term for a class of mass spectrometer that utilizes a static electric or magnetic sector or some combination of the two as a mass analyzer. ...

## Instrumentation

### Ion source

The ion source is the part of the mass spectrometer that ionizes the material under analysis (the analyte). The ions are then transported by magnetic or electric fields to the mass analyzer. Magnetic field lines shown by iron filings Magnetostatics Electrodynamics Electrical Network Tensors in Relativity This box:      In physics, the magnetic field is a field that permeates space and which exerts a magnetic force on moving electric charges and magnetic dipoles. ... In physics, the space surrounding an electric charge or in the presence of a time-varying magnetic field has a property called an electric field. ...

### Mass analyzer

Mass analyzers separate the ions according to their mass-to-charge ratio. All mass spectrometers are based on dynamics of charged particles in electric and magnetic fields in vacuum where the following two laws apply: It has been suggested that Charge-to-mass ratio be merged into this article or section. ...

$mathbf{F} = q (mathbf{E} + mathbf{v} times mathbf{B})$ (Lorentz force law)
$mathbf{F}=mmathbf{a}$ (Newton's second law of motion)

where F is the force applied to the ion, m is the mass of the ion, a is the acceleration, q is the ionic charge, E is the electric field, and v x B is the vector cross product of the ion velocity and the magnetic field In physics, the Lorentz force is the force exerted on a charged particle in an electromagnetic field. ... Newtons laws of motion are the three scientific laws which Isaac Newton discovered concerning the behaviour of moving bodies. ... In mathematics, the cross product is a binary operation on vectors in three dimensions. ...

Equating the above expressions for the force applied to the ion yields:

$(m/q)mathbf{a} = mathbf{E}+ mathbf{v} times mathbf{B}$

This differential equation is the classic equation of motion of charged particles. Together with the particle's initial conditions it completely determines the particle's motion in space and time and therefore is the basis of every mass spectrometer. It immediately reveals that two particles with the same physical quantity m/q behave exactly the same. Thus all mass spectrometers actually measure m/q and strictly speaking should be called mass-to-charge spectrometers. When presenting data, it is common to use the (officially) dimensionless m/z (called mass-to-charge ratio, although (more accurately) it represents the ratio of the mass number and the charge number), where z is the number of elementary charges (e) on the ion (z=q/e). The mass-to-charge ratio m/q, is a physical quantity measured in mass spectrometry. ... It has been suggested that Charge-to-mass ratio be merged into this article or section. ... The elementary charge (symbol e or sometimes q) is the electric charge carried by a single proton, or equivalently, the negative of the electric charge carried by a single electron. ...

There are many types of mass analyzers, using either static or dynamic fields, and magnetic or electric fields, but all operate according to this same law. Each analyzer type has its strengths and weaknesses. Many mass spectrometers use two or more mass analyzers for tandem mass spectrometry (MS/MS). In addition to the more common mass analyzers listed below, there are other less common ones designed for special situations.

#### Sector

For more details on this topic, see sector instrument.

A sector field mass analyzer uses an electric and/or magnetic field to affect the path and/or velocity of the charged particles in some way. As shown above, sector instruments change the direction of ions that are accelerated through the mass analyzer. The ions enter a magnetic or electric field which bends the ion paths depending on their mass-to-charge ratios, deflecting the more charged and faster-moving, lighter ions more. The ions eventually reach the detector and their relative abundances are measured. The analyzer can be used to select a narrow range of m/q or to scan through a range of m/q to catalog the ions present.[4] A sector instrument is a general term for a class of mass spectrometer that utilizes a static electric or magnetic sector or some combination of the two as a mass analyzer. ... This article is about velocity in physics. ... This box:      Electric charge is a fundamental conserved property of some subatomic particles, which determines their electromagnetic interaction. ... A sector instrument is a general term for a class of mass spectrometer that utilizes a static electric or magnetic sector or some combination of the two as a mass analyzer. ...

#### Time-of-flight

For more details on this topic, see time-of-flight mass spectrometry.

For more details on this topic, see Quadrupole mass analyzer.

For more details on this topic, see quadrupole ion trap.

The quadrupole ion trap works on the same physical principles as the QMS, but the ions are trapped and sequentially ejected. Ions are created and trapped in a mainly quadrupole RF potential and separated by m/q, non-destructively or destructively. A quadrupole ion trap (also known as a Paul trap, QIT, twisted quadrupole ion trap or sometimes just ion trap) refers to an ion trap that uses static and radio frequency (RF) ~1MHz oscillating AC electric fields to trap ions as well a mass spectrometer that uses such a trap... A quadrupole ion trap (also known as a Paul trap, QIT, twisted quadrupole ion trap or sometimes just ion trap) refers to an ion trap that uses static and radio frequency (RF) ~1MHz oscillating AC electric fields to trap ions as well a mass spectrometer that uses such a trap...

There are many mass/charge separation and isolation methods but most commonly used is the mass instability mode in which the RF potential is ramped so that the orbit of ions with a mass a > b are stable while ions with mass b become unstable and are ejected on the z-axis onto a detector.

Ions may also be ejected by the resonance excitation method, whereby a supplemental oscillatory excitation voltage is applied to the endcap electrodes, and the trapping voltage amplitude and/or excitation voltage frequency is varied to bring ions into a resonance condition in order of their mass/charge ratio.[6][7]

The cylindrical ion trap mass spectrometer is a derivative of the quadrupole ion trap mass spectrometer. Scheme of a Quadrupole ion trap of classical setup with a particle of positive charge (red), surrounded by a cloud of similarly charged particles (red). ...

A linear quadrupole ion trap is similar to a QIT, but traps ions in a 2D quadrupole field, instead of a 3D quadrupole field as in a QIT. Thermo Fisher's LTQ ("linear trap quadrupole") is an example of the Linear ion trap.[8] Scheme of a Quadrupole ion trap of classical setup with a particle of positive charge (red), surrounded by a cloud of similarly charged particles (red). ...

#### Fourier transform ion cyclotron resonance

For more details on this topic, see Fourier transform mass spectrometry.

Fourier transform mass spectrometry, or more precisely Fourier transform ion cyclotron resonance MS, measures mass by detecting the image current produced by ions cyclotroning in the presence of a magnetic field. Instead of measuring the deflection of ions with a detector such as an electron multiplier, the ions are injected into a Penning trap (a static electric/magnetic ion trap) where they effectively form part of a circuit. Detectors at fixed positions in space measure the electrical signal of ions which pass near them over time producing cyclical signal. Since the frequency of an ion's cycling is determined by its mass to charge ratio, this can be deconvoluted by performing a Fourier transform on the signal. FTMS has the advantage of high sensitivity (since each ion is 'counted' more than once) and much high resolution and thus precision.[9][10] Fourier Transform Ion Cylotron Resonance also known as Fourier Transfomr Mass Spectrometry is a type of mass analyzer (or mass spectrometer) for determining the mass to charge ratio (m/z) of ions based on the cyclotron frequency of the ions in a magnetic field. ... Fourier Transform Ion Cylotron Resonance also known as Fourier Transfomr Mass Spectrometry is a type of mass analyzer (or mass spectrometer) for determining the mass to charge ratio (m/z) of ions based on the cyclotron frequency of the ions in a magnetic field. ... Fourier Transform Ion Cyclotron Resonance, also known as Fourier Transform Mass Spectrometry, is a type of mass analyzer (or mass spectrometer) for determining the mass to charge ratio (m/z) of ions based on the cyclotron frequency of the ions in a magnetic field. ... A pair of Dee electrodes with loops of coolant pipes on their surface at the Lawrence Hall of Science. ... An electron multiplier (continuous dynode electron multiplier) multiplies charge. ... Penning traps are devices for the storage of charged particles using a constant magnetic field and a constant electric field. ... An ion trap is a combination of electric or magnetic fields that captures ions in a region of a vacuum system or tube. ... In mathematics, the Fourier transform is a certain linear operator that maps functions to other functions. ... Fourier Transform Ion Cylotron Resonance, also known as Fourier Transform Mass Spectrometry, is a type of mass analyzer (or mass spectrometer) for determining the mass to charge ratio (m/z) of ions based on the cyclotron frequency of the ions in a magnetic field. ...

Ion cyclotron resonance is an older mass analysis technique similar to FTMS except that ions are detected with a traditional detector. Ions trapped in a Penning trap are excited by an RF electric field until they impact the wall of the trap where the detector is located with ions of different mass being resolved in time. A pair of Dee electrodes with loops of coolant pipes on their surface at the Lawrence Hall of Science. ... Penning traps are devices for the storage of charged particles using a constant magnetic field and a constant electric field. ...

#### Orbitrap

For more details on this topic, see Orbitrap.

The Orbitrap is the most recently introduced mass analyser. In the Orbitrap, ions are electrostatically trapped in an orbit around a central, spindle-shaped electrode. The electrode confines the ions so that they both orbit around the central electrode and oscillate back and forth along the central electrode's long axis. This oscillation generates an image current in the detector plates which is recorded by the instrument. The frequencies of these image currents depend on the mass to charge ratios of the ions in the Orbitrap. Mass spectra are obtained by Fourier transformation of the recorded image currents. An orbitrap mass spectrometer is an ion trapping device that consists of an outer barrel-like electrode and a coaxial inner spindle-like electrode that form an electrostatic field with quadro-logarithmic potential distribution. ... An orbitrap mass spectrometer is an ion trapping device that consists of an outer barrel-like electrode and a coaxial inner spindle-like electrode that form an electrostatic field with quadro-logarithmic potential distribution. ... Electrostatics is the branch of physics that deals with the force exerted by a static (i. ... The Fourier transform, named after Jean Baptiste Joseph Fourier, is an integral transform that re-expresses a function in terms of sinusoidal basis functions, i. ...

Similar to Fourier transform ion cyclotron resonance mass spectrometers, Orbitraps have a high mass accuracy, high sensitivity and a good dynamic range.[11] Fourier Transform Ion Cyclotron Resonance, also known as Fourier Transform Mass Spectrometry, is a type of mass analyzer (or mass spectrometer) for determining the mass to charge ratio (m/z) of ions based on the cyclotron frequency of the ions in a magnetic field. ...

### Detector

The final element of the mass spectrometer is the detector. The detector records the charge induced or current produced when an ion passes by or hits a surface. In a scanning instrument the signal produced in the detector during the course of the scan versus where the instrument is in the scan (at what m/q) will produce a mass spectrum, a record of ions as a function of m/q. A mass spectrum is an intensity vs. ...

Typically, some type of electron multiplier is used, though other detectors including Faraday cups and ion-to-photon detectors are also used. Because the number of ions leaving the mass analyzer at a particular instant is typically quite small, significant amplification is often necessary to get a signal. Microchannel Plate Detectors are commonly used in modern commercial instruments.[12] In FTMS and Orbitraps, the detector consists of a pair of metal surfaces within the mass analyzer/ion trap region which the ions only pass near as they oscillate. No DC current is produced, only a weak AC image current is produced in a circuit between the electrodes. Other inductive detectors have also been used. [13] An electron multiplier (continuous dynode electron multiplier) multiplies charge. ... A faraday cup is a metal (conductive) cup meant to recatch secondary particles. ... Microchannel plate detector from the Daresbury Recoil Separator A micro-channel plate (MCP) is a planar component used for detection of particles (electrons or ions) and impinging radiation (ultraviolet radiation and X-rays). ... Fourier Transform Ion Cylotron Resonance, also known as Fourier Transform Mass Spectrometry, is a type of mass analyzer (or mass spectrometer) for determining the mass to charge ratio (m/z) of ions based on the cyclotron frequency of the ions in a magnetic field. ... An orbitrap mass spectrometer is an ion trapping device that consists of an outer barrel-like electrode and a coaxial inner spindle-like electrode that form an electrostatic field with quadro-logarithmic potential distribution. ...

## Tandem MS (MS/MS)

Tandem mass spectrometry involves multiple steps of mass selection or analysis, usually separated by some form of fragmentation. A tandem mass spectrometer is one capable of multiple rounds of mass spectrometry. For example, one mass analyzer can isolate one peptide from many entering a mass spectrometer. A second mass analyzer then stabilizes the peptide ions while they collide with a gas, causing them to fragment by collision-induced dissociation (CID). A third mass analyzer then catalogs the fragments produced from the peptides. Tandem MS can also be done in a single mass analyzer over time as in a quadrupole ion trap. There are various methods for fragmenting molecules for tandem MS, including collision-induced dissociation (CID), electron capture dissociation (ECD), electron transfer dissociation (ETD), infrared multiphoton dissociation (IRMPD) and blackbody infrared radiative dissociation (BIRD). An important application using tandem mass spectrometry is in protein identification.[14] Mass spectrometry is a technique for separating ions by their mass-to-charge (m/z) ratios. ... Peptides (from the Greek Ï€ÎµÏ€Ï„Î¿Ï‚, digestible), are the family of short molecules formed from the linking, in a defined order, of various Î±-amino acids. ... In Mass spectrometry, collision-induced dissociation (CID), refered to by some as collisionally activated dissociation (CAD), is a mechanism by which to fragment molecular ions in the gas phase. ... A quadrupole ion trap (also known as a Paul trap, QIT, twisted quadrupole ion trap or sometimes just ion trap) refers to an ion trap that uses static and radio frequency (RF) ~1MHz oscillating AC electric fields to trap ions as well a mass spectrometer that uses such a trap... In Mass spectrometry, collision-induced dissociation (CID), refered to by some as collisionally activated dissociation (CAD), is a mechanism by which to fragment molecular ions in the gas phase. ... In mass spectrometry electron capture dissociation (ECD) is a method of fragmenting gas phase ions for tandem mass spectrometric analysis (structural elucidation). ... Electron transfer dissociation (ETD) is a method to fragment ions in a mass spectrometer. ... Infrared multiphoton dissociation (IRMPD) is a technique used in mass spectrometry to fragment molecules in the gas phase usually for structural anaylsis of the original (parent) molecule. ... In mass spectrometry blackbody infrared radiative dissociation (BIRD) is a method for fragmenting gas phase ions for tandem mass spectrometric analysis (structural elucidation). ... Mass spectrometry (previously called mass spectroscopy (deprecated) or informally, mass-spec and MS) is an analytical technique that measures the mass-to-charge ratio of ions. ...

Tandem mass spectrometry enables a variety of experiments. Although it allows for many uniquely designed experiments some types of experiments are commonly used and built into many commercial mass spectrometers. Examples of these include single reaction monitoring (SRM), multiple reaction monitoring (MRM) and precursor ion scan. In single reaction monitoring the first analyzer allows only a single mass through and the second analyzer monitors for a specifically defined fragment ion. MRM is nearly identical except the second analyzer monitors multiple user defined fragment ions. These monikers are most often used with scanning instruments where the second mass analysis event is duty cycle limited. These experiments are used to increase specificity of detection of known molecules such as in pharmacokinetic studies. Precursor ion scan refers to monitoring for a specific loss from the precursor ion. The first and second mass analyzers scan across the spectrum separated by a user defined m/z value. This experiment is used to detect specific motifs within unknown molecules.

## Common Mass Spectrometer Configurations & Techniques

When all of the elements (source, analyzer and detector) of a mass spectrometer are combined to form a complete instrument and the specific configuration becomes common a new name, often an abbreviation of one or more of the internal components, becomes attached to the specific configuration and can become, within certain circles, more well known than the specific internal components. The most ubiquitous example of this is MALDI-TOF, which simply refers to combining a Matrix-assisted laser desorption/ionization source with a Time-of-flight mass analyzer. The MALDI-TOF moniker is, however, often more widely recognized by the non-mass spectrometrist scientist than MALDI or TOF individually as if inseparable. Other examples include inductively coupled plasma-mass spectrometry (ICP-MS), accelerator mass spectrometry (AMS), Thermal ionization-mass spectrometry (TIMS) and spark source mass spectrometry (SSMS). Sometimes the use of the generic "MS" actually implies a very specific mass analyzer and detection system as with AMS, which is always sector based. In other cases there are common configurations that may be implied but not necessarily. Matrix-Assisted Laser Desorption/Ionization (MALDI) is a soft ionization technique used in mass spectrometry, allowing, among others, to ionise biomolecules (biopolymers like proteins, peptides and sugarchains) which tend to be more fragile and quickly lose structure when ionised by more conventional ionisation methods. ... MALDI TOF mass spectrometer Matrix-assisted laser desorption/ionization (MALDI) is a soft ionization technique used in mass spectrometry, allowing the analysis of biomolecules (biopolymers such as proteins, peptides and sugars) and large organic molecules (such as polymers, dendrimers and other macromolecules), which tend to be fragile and fragment when... The Time of flight (TOF) method of measuring particle mass-to-charge ratio is done as follows. ... ICP-MS (Inductively coupled plasma mass spectrometry) is a type of mass spectrometry that is highly sensitive and capable of the determination of a range of metals and several non-metals at concentrations below one part in 1012. ... Mass spectrometry is a technique for separating ions by their mass-to-charge (m/z) ratios. ... In Thermal Ionisation, also referred to as Surface Ionisation, chemically-purified material loaded onto a filament which is then heated may cause some of the loaded element to be ionized as it boils off the hot filament. ... Spark ionization (also known as spark source ionization(deprecated)) is a method used to produce gas phase ions from a solid sample. ...

Certain applications of mass spectrometry have developed monikers that although technically referring to a broad application also tend to indicate a specific or a limited number of instrument configurations. An example of this is isotope ratio mass spectrometry (IRMS). Despite only specifically indicating an application, the use of a limited number of sector based mass analyzers is implied and the name is used to refer to both the application and the instrument used for the application. Isotope ratio mass spectrometry (IRMS) is a specialist field of mass spectrometry, concerned with measuring the relative abundance of atomic isotopes. ...

## Other Separation Techniques Combined with Mass spectrometry

An important enhancement to the mass resolving and determining capacity of mass spectrometry is the combination of mass spectrometry with analysis techniques that resolve mixtures of compounds in a sample based on other characteristics before introduction into the mass spectrometer.

### Liquid chromatography/MS

Similar to gas chromatography MS (GC/MS), liquid chromatography mass spectrometry (LC/MS or LC-MS) separates compounds chromatographically before they are introduced to the ion source and mass spectrometer. It differs from GC/MS in that the mobile phase is liquid, usually a combination of water and organic solvents, instead of gas. Most commonly, an electrospray ionization source is used in LC/MS. Liquid chromatography-mass spectrometry (LC-MS)is an analytical chemistry technique that combines the physical separation capabilities of liquid chromatography (aka HPLC) with the mass analysis capabilities of mass spectrometry. ... Impact from a water drop causes an upward rebound jet surrounded by circular capillary waves. ... For other uses, see Solvent (disambiguation). ... Electrospray (nanoSpray) ionization source Electrospray ionization (ESI) is a technique used in mass spectrometry to produce ions. ...

### IMS/MS

Ion mobility spectrometry/mass spectrometry is a technique where ions are first separated by drift time through some pressure of neutral gas given an electrical potential gradient before being introduced into a mass spectrometer. An ion mobility spectrometer (IMS) is a spectrometer capable of detecting and identifying very low concentrations of chemicals based upon the differential migration of gas phase ions through a homogeneous electric field. ...

The drift time is a measure of the radius relative to the charge of the ion. The duty cycle of IMS (time over which the experiment takes place) is longer than most mass spectrometers such that the mass spectrometer can sample along the course of the IMS separation. This produces data about the IMS separation and the mass-to-charge ratio of the ions in a manner similar to LC/MS.[16] Liquid chromatography-mass spectrometry (LC-MS)is an analytical chemistry technique that combines the physical separation capabilities of liquid chromatography (aka HPLC) with the mass analysis capabilities of mass spectrometry. ...

The duty cycle of IMS is short relative to liquid chromatography or gas chromatography separations and can thus be coupled to such techniques producing triply hyphenated techniques such as LC/IMS/MS.

## Data and analysis

### Data representations

Mass spectrometry produces various types of data. The most ubiquitous data representation is the mass spectrum. A mass spectrum is an intensity vs. ...

Certain types of mass spectrometry data are best represented as a mass chromatogram. Types of chromatograms include selected ion monitoring (SIM), total ion current (TIC), and selected reaction monitoring chromatogram (SRM), among many others. The term Mass Chromatogram refers to the representation of mass spectrometry data as a chromatogram, where the x-axis represents time and the y-axis represents signal intensity. ...

Other types of mass spectrometry data are well represented as a contour map of mass-to-charge on one axis, intensity on another and an additional experimental parameter (often time) on the third axis, thus producing a three dimensional surface. Example of a topographic map with contour lines Topographic maps, also called contour maps, topo maps or topo quads (for quadrangles), are maps that show topography, or land contours, by means of contour lines. ...

### Data analysis

Basics

Mass spectrometry data analysis is a complicated subject matter that is very specific to the type of experiment producing the data. There are several general subdivisions of data that are fundamental to beginning to understand any data.

Many mass spectrometers work in either negative ion mode or positive ion mode. It is very important to know whether the observed ions are negatively or positively charged. This is often important in determining the neutral mass but it also indicates something about the nature of the molecules.

There are many different types of ion sources that behave very differently from each other. A source such as an electron ionization source produces many fragments and mostly odd electron species with one charge, whereas a source such as an electrospray source usually produces quasimolecular even electron species that may be multiply charged.

Tandem mass spectrometry purposely produces fragment ions post-source and can drastically change the sort of data achieved by an experiment.

By understanding the origin of a sample certain expectations can be assumed. For example, if the sample is coming from a synthesis/manufacturing process impurities are likely to be present that are related to the major component. If the sample is a relatively crude preparation of a biological sample, the sample likely contains a certain amount of salt that may form adducts with the analyte molecules in certain analyses. Wikipedia does not yet have an article with this exact name. ...

Results can also depend heavily on how the sample was prepared and how it was run/introduced. An important example is which matrix was used for MALDI spotting, since much of the energetics of the desorption/ionization event is controlled by the matrix rather than the laser power. Sometimes samples are spiked with sodium or another ion-carrying species to produce adducts rather than a protonated species.

The most commonly overlooked basic question by non-mass spectrometrists trying to use mass spectrometry or interact with a mass spectrometrist is what is the over-arching goal of the project. To interpret data one must know the desired outcome (and have collected the right data in the first place). There are many bits of information that can be gleaned from mass spectrometry data, such as the masses of the molecules, the purity of the sample, and the structure of the molecules. Each of these questions requires a different approach. Simply asking for a "mass-spec" will most likely not answer the real question at hand.

## Applications

### Isotope ratio MS: isotope dating and tracking

Mass spectrometer to determine the 16O/18O and 12C/13C isotope ratio on biogenous carbonate
Main article: Isotope ratio mass spectrometry

### Trace gas analysis

Several techniques use ions created in a dedicated ion source injected into a flow tube or a drift tube: selected ion flow tube (SIFT-MS), and proton transfer reaction (PTR-MS), are variants of chemical ionization dedicated for trace gas analysis of air, breath or liquid headspace using well defined reaction time allowing calculations of analyte concentrations from the known reaction kinetics without the need for internal standard or calibration. Selected Ion Flow Tube Mass Spectrometry is a sensitive and quantitative mass spectrometry technique for trace gas analyses using chemical ionisation of sample trace gases by selected positive ions during a well-defined time period along a flow tube. ... Chemical ionization (CI) is an ionization technique used in mass spectrometry. ...

### Atom Probe

Main article: Atom probe

An atom probe is an instrument that combines time-of-flight mass spectrometry and field ion microscopy (FIM) to map the location of individual atoms. The atom probe is an atomic-resolution microscope used in materials science that was invented in 1967 by Erwin MÃ¼ller. ... The atom probe is an atomic-resolution microscope used in materials science that was invented in 1967 by Erwin MÃ¼ller. ... The Time of flight (TOF) method of measuring particle mass-to-charge ratio is done as follows. ... Field ion microscopy (FIM) is an analytical technique used in materials science. ...

### Pharmacokinetics

Main article: Pharmacokinetics

Pharmacokinetics is often studied using mass spectrometry because of the complex nature of the matrix (often blood or urine) and the need for high sensitivity to observe low dose and long time point data. The most common instrumentation used in this application is LC-MS with a triple quadrupole mass spectrometer. Tandem mass spectrometry is usually employed for added specificity. Standard curves and internal standards are used for quantitation of usually a single pharmaceutical in the samples. The samples represent different time points as a pharmaceutical is administered and then metabolized or cleared from the body. Blank or t=0 samples taken before administration are important in determining background and insuring data integrity with such complex sample matrices. Much attention is paid to the linearity of the standard curve; however it is not uncommon to use curve fitting with more complex functions such as quadratics since the response of most mass spectrometers is less than linear across large concentration ranges.[17][18][19] Pharmacokinetics (in Greek: pharmacon meaning drug, and kinetikos meaning putting in motion) is a branch of pharmacology dedicated to the determination of the fate of substances administered externally to a living organism. ... Liquid chromatography-mass spectrometry (LC-MS)is an analytical chemistry technique that combines the physical separation capabilities of liquid chromatography (aka HPLC) with the mass analysis capabilities of mass spectrometry. ... The quadrupole mass analyzer is one type of mass analyzer used in mass spectrometry. ...

There is currently considerable interest in the use of very high sensitivity mass spectrometry for microdosing studies, which are seen as a promising alternative to animal experimentation. Microdosing is a technique for studying the behaviour of compounds in vivo through the administration of doses so low they are unlikely to produce whole-body effects, but high enough to allow the cellular response to be studied. ... This article is in need of attention from an expert on the subject. ...

### Protein Mass Spectrometry

Main article: Protein mass spectrometry

Mass spectrometry is an important emerging method for the characterization of proteins. The two primary methods for ionization of whole proteins are electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI). In keeping with the performance and mass range of available mass spectrometers, two approaches are used for characterizing proteins. In the first, intact proteins are ionized by either of the two techniques described above, and then introduced to a mass analyser. This approach is referred to as "top-down" strategy of protein analysis. In the second, proteins are enzymatically digested into smaller peptides using an agent such as trypsin or pepsin. Other proteolytic agents are also used. The collection of peptide products are then introduced to the mass analyser. This peptide mass fingerprinting (PMF) approach of protein analysis is also referred to as the "bottom-up" approach. Protein mass spectrometry refers to the application of mass spectrometry to the study of proteins. ... Electrospray (nanoSpray) ionization source Electrospray ionization (ESI) is a technique used in mass spectrometry to produce ions. ... MALDI TOF mass spectrometer Matrix-assisted laser desorption/ionization (MALDI) is a soft ionization technique used in mass spectrometry, allowing the analysis of biomolecules (biopolymers such as proteins, peptides and sugars) and large organic molecules (such as polymers, dendrimers and other macromolecules), which tend to be fragile and fragment when... Top-down proteomics is a method of protein identification that uses an ion trapping mass spectrometer to store an isolated protein ion for mass measurement and tandem mass spectrometry analysis. ... Peptides are the family of molecules formed from the linking, in a defined order, of various amino acids. ... Trypsin (EC 3. ... Pepsin is a digestive protease (EC 3. ... Peptide mass fingerprinting (also known as protein fingerprinting) (PMF) is an analytical technique for protein identification that was developed by John Yates and colleagues (3). ...

### Space exploration

As a standard method for analysis several mass spectrometers have reached other planets and moons. Two were taken to Mars by the Viking program. In early 2005 the Cassini-Huygens mission delivered a specialized GC-MS instrument aboard the Huygens probe through the atmosphere of Titan, the largest moon of the planet Saturn. This instrument analyzed atmospheric samples along its descent trajectory and was able to vaporize and analyze samples of Titan's frozen, hydrocarbon covered surface once the probe had landed. These measurements compare the abundance of isotope(s) of each particle comparatively to earth's natural abundance.[20] Adjectives: Martian Atmosphere Surface pressure: 0. ... Viking mission profile. ... Cassini-Huygens is a joint NASA/ESA/ASI unmanned space mission intended to study Saturn and its moons. ... ... The Huygens probe, supplied by the European Space Agency (ESA) and named after the Dutch 17th century astronomer Christiaan Huygens, is an atmospheric entry probe carried to Saturns moon Titan as part of the Cassini-Huygens mission. ... Titan (, from Ancient Greek Î¤á¿‘Ï„Î¬Î½) or Saturn VI is the largest moon of Saturn and the only moon known to have a dense atmosphere. ... Atmospheric characteristics Atmospheric pressure 140 kPa Hydrogen >93% Helium >5% Methane 0. ...

Mass spectrometers are also widely used in space missions to measure the composition of plasmas. For example, the Cassini spacecraft carries the Cassini Plasma Spectrometer (CAPS), [21] which measures the mass of ions in Saturn's magnetosphere. A magnetosphere is the region around an astronomical object in which phenomena are dominated or organized by its magnetic field. ...

### Respired Gas Monitor

Mass spectrometers were used in hospitals for respiratory gas analysis beginning around 1975 through the end of the century, some are likely still in use but none are currently being manufactured.[22]

Found mostly in the operating room they were a part of a complex system in which respired gas samples from patients undergoing anesthesia were drawn into the instrument through a valve mechanism designed to sequentially connect up to 32 rooms to the mass spectrometer. A computer directed all operations of the system, the data collected from the mass spectrometer was delivered to the individual rooms for the anesthesiologist to use. An operating theatre or operating room is a room within a hospital within which surgical operations are carried out. ... Anesthesia or anaesthesia (see spelling differences) has traditionally meant the condition of having the perception of pain and other sensations blocked. ...

This magnetic sector mass spectrometer's uniqueness may have been the fact that a plane of detectors, each purposely positioned to collect all of the ion species expected to be in the samples, allowed the instrument to simultaneously report all of the patient respired gases. Although the mass range was limited to slightly over 120 u, fragmentation of some of the heavier molecules negated the need for a higher detection limit. [23] The unified atomic mass unit (u), or dalton (Da), is a small unit of mass used to express atomic and molecular masses. ...

Mass spectrometry software is any software for data acquisition, analysis or data representation in mass spectrometry. ... In an Electron spectrometer, an incoming beam of electrons is bent with electric or magnetic fields. ... The atom probe is an atomic-resolution microscope used in materials science that was invented in 1967 by Erwin MÃ¼ller. ... Schematic diagram of uranium isotope separation in the calutron. ... A Helium mass spectrometer (often called a leak detector) or sniffer, is a scientific instrument, used to detect very small leaks, typically using a vacuum and injecting helium around a chamber or cavity. ... Ion-attachment mass spectrometry (IAMS) is a form of mass spectrometry that uses a soft form of ionization similar to chemical ionization in which a cation is attached to the analyte molecule in a reactive collision: Where M is the analyte molecule, X+ is the cation and A is a... MALDI MS image shows distribution of m/z 616 in a whole-body tissue section of a rat. ... Membrane introduction mass spectrometry (MIMS) is a method of introducing analytes into the mass spectrometers vacuum chamber via a permeable membrane. ... The process known as secondary ion mass spectrometry (SIMS) involves bombarding the surface to be tested with a stream of ions. ... A Taylor cone refers to the cone observed in electrospray and hydrodynamic spray processes from which a jet of charged particles emanates above a threshold voltage. ...

### Manufacturers of Mass Spectrometry Equipment

Agilent Technologies (NYSE: A) (Agilent for short) is a measurement and instrument company headquartered in Santa Clara, California. ... Bruker originally started as a German company specialized in nuclear magnetic resonance (NMR), but has evolved into an international company with products covering a gamut of biological, chemical and medical fields. ... CovalX AG is a ZÃ¼rich, Switzerland-based company which develops and manufactures scientific instrumentation for academic research and industrial use. ... A manufacturer of scanning electron microscopes, transmission electron microscopes, electron microprobes, electron beam lithography systems. ... LECO Corporation, founded in 1936 by Carl Schultz and George Krasl, is an analytical instrumentation developer and manufacturer located in St. ... MDS Inc. ... PerkinElmer, Inc. ... Shimadzu Corporation (å³¶æ´¥è£½ä½œæ‰€) is a manufacturer of precision instruments, measuring instruments and medical equipment, based in Kyoto, Kyoto. ... Thermo Electron Corporation (Thermo) NYSE: TMO (incorporated 1956) is a major provider of analytical instruments and services for a variety of domains. ... Waters is a publicly traded laboratory analytical instrument and software company headquartered in Milford, Massachusetts. ... Varian, Inc. ...

## References

1. ^ Sparkman, O. David (2000). Mass spectrometry desk reference. Pittsburgh: Global View Pub. ISBN 0-9660813-2-3.
2. ^ Measuring Mass: From Positive Rays to Proteins by Michael A. Grayson (Editor) (ISBN 0-941901-31-9)
3. ^ A. P. Bruins (1991). "Mass spectrometry with ion sources operating at atmospheric pressure". Mass Spectrometry Reviews 10 (1): 53-77. doi:10.1002/mas.1280100104.
4. ^ Extending the mass range of a sector mass spectrometer, John S Cottrell, Roger J Greathead, Mass Spectrometry Reviews Vol 5, 1986. pp 215-247
5. ^ Time-of-flight mass analyzers H. Wollnik, Mass Spectrometry Reviews, Vol 12, 1993, pp 89-114
6. ^ Paul W., Steinwedel H. (1953). "Ein neues Massenspektrometer ohne Magnetfeld". RZeitschrift für Naturforschung A 8 (7): 448-450
7. ^ R. E. March (2000). "Quadrupole ion trap mass spectrometry: a view at the turn of the century". International Journal of Mass Spectrometry 200 (1-3): 285-312. doi:10.1016/S1387-3806(00)00345-6.
8. ^ Schwartz, Jae C.; Michael W. Senko and John E. P. Syka (June 2002). "A two-dimensional quadrupole ion trap mass spectrometer". Journal of the American Society for Mass Spectrometry 13 (6): 659-669. Elsevier Science B.V.. doi:10.1016/S1044-0305(02)00384-7.
9. ^ M. B. Comisarow and A. G. Marshall (1974). "Fourier transform ion cyclotron resonance spectroscopy". Chemical Physics Letters 25 (2): 282-283. doi:10.1016/0009-2614(74)89137-2.
10. ^ Marshall, A. G.; Hendrickson, C. L.; Jackson, G. S. (1998). "Fourier transform ion cyclotron resonance mass spectrometry: a primer". Mass Spectrometry Reviews 17 (1): 1-34. doi:10.1002/(SICI)1098-2787(1998)17:1%3C1::AID-MAS1%3E3.0.CO;2-K.
11. ^ Q. Hu, R. J. Noll, H. Li, A. Makarov, M. Hardman and R. G. Cooks (2005). "The Orbitrap: a new mass spectrometer". Journal of Mass Spectrometry 40 (4): 430-443. doi:10.1002/jms.856.
12. ^ F. Dubois, R. Knochenmuss, R. Zenobi, A. Brunelle, C. Deprun and Y. L. Beyec (1999). "A comparison between ion-to-photon and microchannel plate detectors". Rapid Communications in Mass Spectrometry 13 (9): 786-791. doi:10.1002/(SICI)1097-0231(19990515)13:9%3C786::AID-RCM566%3E3.0.CO;2-3.
13. ^ M. A. Park, J. H. Callahan and A. Vertes (1994). "An inductive detector for time-of-flight mass spectrometry". Rapid Communications in Mass Spectrometry 8 (4): 317-322. doi:10.1002/rcm.1290080407.
14. ^ Robert K. Boyd (1994). "Linked-scan techniques for MS/MS using tandem-in-space instruments". Mass Spectrometry Reviews 13 (5-6): 359-410. doi:10.1002/mas.1280130502.
15. ^ Eiceman, G.A. (2000). Gas Chromatography. In R.A. Meyers (Ed.), Encyclopedia of Analytical Chemistry: Applications, Theory, and Instrumentation, pp. 10627. Chichester: Wiley. ISBN 0-471-97670-9
16. ^ L. M. Matz, G. R. Asbury and H. H. Hill (2002). "Two-dimensional separations with electrospray ionization ambient pressure high-resolution ion mobility spectrometry/quadrupole mass spectrometry". Rapid Communications in Mass Spectrometry 16 (7): 670-675. doi:10.1002/rcm.623.
17. ^ Increasing Speed and Throughput When Using HPLC-MS/MS Systems for Drug Metabolism and Pharmacokinetic Screening, Y. Hsieh and W.A. Korfmacher, Current Drug Metabolism Volume 7, Number 5, 2006, Pp. 479-489
18. ^ Covey TR, Lee ED, Henion JD. 1986. High-speed liquid chromatography/tandem mass spectrometry for the determination of drugs in biological samples. Anal Chem 58:2453-2460.
19. ^ Thermospray liquid chromatography/mass spectrometry determination of drugs and their metabolites in biological fluids. Covey TR et al. Anal Chem. 1985 Feb;57(2):474-81
20. ^ S. Petrie and D. K. Bohme (2007). "Ions in space". Mass Spectrometry Reviews 26 (2): 258-280. doi:10.1002/mas.20114.
21. ^ http://caps.space.swri.edu/
22. ^ Expired gas monitoring by mass spectrometry in a respiratory intensive care unit. Riker JB, Haberman B. Crit Care Med. 1976 Sep-Oct;4(5):223-9
23. ^ J. W. W. Gothard, C. M. Busst, M. A. Branthwaite, N. J. H. Davies and D. M. Denison (1980). "Applications of respiratory mass spectrometry to intensive care". Anaesthesia 35 (9): 890-895. doi:10.1111/j.1365-2044.1980.tb03950.x.

## Bibliography

• Tureček, František; McLafferty, Fred W. (1993). Interpretation of mass spectra. Sausalito, Calif: University Science Books. ISBN 0-935702-25-3.
• Edmond de Hoffman; Vincent Stroobant (2001). Mass Spectrometry: Principles and Applications, 2nd ed., John Wiley and Sons. ISBN 0-471-48566-7.
• Downard, Kevin (2004). Mass Spectrometry - A Foundation Course. Cambridge UK: Royal Society of Chemistry. ISBN 0-85404-609-6.
• Siuzdak, Gary (1996). Mass spectrometry for biotechnology. Boston: Academic Press. ISBN 0-12-647471-0.
• Dass, Chhabil (2001). Principles and practice of biological mass spectrometry. New York: John Wiley. ISBN 0-471-33053-1.
• Jnrgen H. Gross. Mass Spectrometry: A Textbook. Berlin: Springer-Verlag. ISBN 3-540-40739-1.
• Muzikar, P., et al., "Accelerator Mass Spectrometry in Geologic Research", Geological Society of America Bulletin v. 115 (2003) p. 643 - 654.
• David O. Sparkman. Mass Spectrometry Desk Reference. Pittsburgh: Global View Pub. ISBN 0-9660813-9-0.
• Tuniz, C. (1998). Accelerator mass spectrometry: ultrasensitive analysis for global science. Boca Raton: CRC Press. ISBN 0-8493-4538-3.

Results from FactBites:

 Mass spectrometry - Mass Spectrometry Wiki (3059 words) Mass spectrometry is an analytical technique used to measure the mass-to-charge ratio of w:ions. The cylindrical ion trap mass spectrometer is a derivative of the quadrupole ion trap mass spectrometer. A mass spectrometer produces a mass spectrum, which is a plot of the relative abundances of ions as a function of the the ratio of their mass-to-charge values.
 Mass Spectrometry (2839 words) A mass spectrum will usually be presented as a vertical bar graph, in which each bar represents an ion having a specific mass-to-charge ratio (m/z) and the length of the bar indicates the relative abundance of the ion. The unit mass resolution is readily apparent in these spectra (note the separation of ions having m/z=39, 40, 41 and 42 in the cyclopropane spectrum). The mass calculator on the right may be used to calculate the exact mass of a molecule based on its elemental composition.
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