Name: ms/ms scan modes and fragment ions
Uploaded: 2025-12-12T12:28:58.000Z
Duration: 1 min 21 s
Channel: JoVE

Tandem mass spectrometry, or MS/MS, combines two mass analyzers in sequence, connected by a collision or interaction cell.
First, the samples are ionized to generate a mixture of ions, which enters the first mass analyzer.
This analyzer separates the ions and selects only a particular ion&#8212;the precursor ion&#8212;to move into the collision cell.
The collision cell contains inert gas molecules, which collide with precursor ions, fragmenting them into product ions.
These ions are run through the second mass analyzer, where they are separated and finally detected.
MS/MS generates various spectra.
Product-ion spectra are obtained when the first analyzer selects a precursor ion and the second analyzer scans all the masses.
Precursor-ion spectra are generated by scanning through precursor ions in the first analyzer and selecting a product-ion in the second analyzer.
To obtain neutral loss spectra, both mass analyzers are scanned together, with the second analyzer offset by the mass of a selected neutral fragment.
MS/MS is used for structural elucidation and complex mixture analysis.

spectrométrie de masse en tandem

Tandem Mass Spectrometry

La spectrom&#233;trie de masse en tandem est une technique qui utilise plusieurs analyseurs de masse en s&#233;rie pour obtenir une bonne s&#233;lectivit&#233; et un rapport signal/bruit plus &#233;lev&#233;s pour l'analyte. Les instruments dot&#233;s de plusieurs analyseurs s&#233;par&#233;s par une cellule d&#8217;interaction permettent une fragmentation secondaire et une &#233;tude s&#233;lectionn&#233;e des ions fragments.
Des fragmentations secondaires se produisent dans la cellule d'interaction et peuvent &#234;tre induites par divers facteurs. La fragmentation induite par collision avec des gaz inertes, tels que N_2, Ar, He, etc., est appel&#233;e dissociation induite par collision (CID). D'autres techniques impliquent une interaction avec la surface par dissociation induite par la surface (SID)&#160;; interaction avec des &#233;lectrons de faible &#233;nergie, appel&#233;e dissociation par capture &#233;lectronique (ECD)&#160;; ou gr&#226;ce &#224; un faisceau laser intense, appel&#233; dissociation photo-induite (PID).
La spectrom&#233;trie de masse en tandem peut &#234;tre utilis&#233;e pour diverses exp&#233;riences en faisant varier le mode de fonctionnement des deux analyseurs de masse. Lorsque le premier analyseur de masse s&#233;lectionne un ion pr&#233;curseur particulier et que le deuxi&#232;me analyseur de masse analyse tous les ions produits fragment&#233;s, cela s'appelle un balayage d'ions produits, et les spectres obtenus par cette exp&#233;rience sont appel&#233;s spectres d'ions produits. Alternativement, lorsque le premier analyseur de masse analyse tous les ions pr&#233;curseurs et que le deuxi&#232;me analyseur de masse s&#233;lectionne un ion produit particulier, cela est appel&#233; &#171; mode ion pr&#233;curseur &#187; et les spectres sont appel&#233;s spectres d&#8217;ions pr&#233;curseurs. Une autre exp&#233;rience peut &#234;tre r&#233;alis&#233;e en balayant simultan&#233;ment les deux analyseurs avec un d&#233;calage d'une masse &#233;gale &#224; un fragment neutre perdu par l'ion &#224; surveiller. Un tel mode est appel&#233; &#171; mode de balayage &#224; perte neutre &#187; et les spectres correspondants sont appel&#233;s spectres &#224; perte neutre.
L'instrumentation de la spectrom&#233;trie de masse tandem peut &#234;tre vari&#233;e. Les spectrom&#232;tres tandem dans l'espace utilisent deux analyseurs de masse ind&#233;pendants dans deux r&#233;gions diff&#233;rentes de l'espace, par exemple un spectrom&#232;tre de masse triple quadrip&#244;le et un spectrom&#232;tre TOF-TOF. D'autre part, un spectrom&#232;tre tandem dans le temps, tel qu'un instrument pi&#232;ge &#224; ions quadripolaire, utilise la m&#234;me r&#233;gion spatiale pour fragmenter les ions et dissocier et analyser un ion d'int&#233;r&#234;t s&#233;lectionn&#233;, mais &#224; des moments diff&#233;rents en expulsant les ions ind&#233;sirables. Des spectrom&#232;tres tandem dans le temps peuvent &#234;tre utilis&#233;s pour r&#233;aliser des exp&#233;riences MS^n.

Spectrométrie de masse en tandem

Tandem mass spectrometry, or MS/MS, combines two mass analyzers in sequence, connected by a collision or interaction cell.
First, the samples are ionized ...

Education

Enseignement

JoVE Core

Analytical Chemistry

Chimie analytique

Unit 1

Unité 1

Principles of Mass Spectrometry

Principes de la spectrométrie de masse

KEY TERMS AND CONCEPTS

TERMES ET CONCEPTS CLÉS

ms/ms scan modes and fragment ions

Tandem mass spectrometry uses two or more mass analyzers in series to improve selectivity and lower chemical noise during analyte detection. A set of analyzers separated by an interaction cell lets the instrument break ions apart and study the fragment ions that form.

Fragmentation happens in the interaction cell and can be caused in several ways. Collision-induced dissociation, or CID, uses inert gases such as nitrogen, argon, or helium. Other methods include surface-induced dissociation (SID), electron-capture dissociation (ECD), and photo-induced dissociation (PID), which uses an intense laser beam.

Tandem mass spectrometry can also run in different scan modes. In a product-ion scan, the first mass analyzer selects one precursor ion, and the second analyzer scans the fragment product ions. The result is a product-ion spectrum. In precursor-ion mode, the first analyzer scans precursor ions, and the second selects one product ion. This gives a precursor-ion spectrum. A neutral-loss scan is different again. Both analyzers scan together with a mass offset that matches the neutral fragment lost by the ion being monitored.

The instrument design can also vary. Tandem-in-space spectrometers use two separate mass analyzers in different regions, such as a triple quadrupole mass spectrometer or a TOF-TOF spectrometer. Tandem-in-time spectrometers, such as a quadrupole ion trap, use the same space at different times to fragment and analyze a chosen ion by removing unwanted ions. These instruments can also perform MSn experiments.

MS/MS Scan Modes and Fragment Ions

mass spectrometry: overview

Mass Spectrometry and Molecular Identity

Mass spectrometry helps identify a compound by measuring its molecular mass and molecular formula. It does this by turning the analyte molecule into ions and then comparing ion abundance with mass-to-charge ratio. One common ionization method is electron ionization, or EI. In EI, high-energy electron beams strike analyte molecules in the gas phase. The beam removes an electron and leaves a molecular ion behind. A molecular ion is a radical cation, so it has a positive charge and an unpaired...

mass spectrometry: isotope effect

Isotope Peaks in Mass Spectra

Isotope peaks in mass spectra show how natural isotope mixtures change the signal of a molecule. Most elements occur as a mix of isotopes, which are atoms of the same element with different numbers of neutrons. Because isotopes have different masses, the same fragment can appear at more than one position in a spectrum. The mass of a molecule depends on which isotopes are present in its atoms. The size of each isotope peak also depends on how common those isotopes are in nature. Carbon is a...

mass spectrometry: molecular fragmentation overview

mass-spectrometry-molecular-fragmentation-overview

Mass Spectrometry Fragmentation Patterns

Mass spectrometry fragmentation patterns show how a molecular ion breaks apart after ionization. When a molecule loses an electron inside the mass spectrometer, its structure becomes unstable. The ion then fragments at bonds that often produce the most stable pieces. One common pattern is cleavage of a single bond in the molecular ion. This break forms a radical and a cation. The bond can split in more than one way, but the favored path is the one that gives the more stable carbocation rather...

mass spectrometers

How Mass Spectrometers Sort Ions

A mass spectrometer sorts charged ions by their mass-to-charge ratio and records their relative abundance. It turns vaporized analyte molecules into ions, separates them, and then measures the signal from each type of ion. The process begins in the ionization chamber. The analyte is in the gas phase inside a vacuum, and it is struck by high-energy electrons. The electrons have about 70 eV of energy, which is enough to remove an electron from the analyte and form a molecular ion. After...

mass spectrum

Reading Peaks in a Mass Spectrum

A mass spectrum shows the charged fragments in an analyte as peaks plotted by mass-to-charge ratio, or m/z. The x-axis gives the mass of each charged fragment divided by the number of charges it carries. The y-axis shows the relative abundance of each charged species based on the signal intensity recorded at the detector. The tallest peak is called the base peak. It is assigned an abundance of 100%, and the other peaks are scaled against it. The peak from the molecular ion is called the parent...

mass spectrum: interpretation

Decoding Molecular Ions in Mass Spectra

Mass spectra help scientists identify an unknown compound by finding the molecular ion peak. The molecular ion peak shows the mass of the intact molecule, but it is often weak or missing because high-energy electron beams cause strong fragmentation. When that happens, a soft-energy electron beam can be used to scan the spectrum and improve the molecular ion signal. Other ionization methods can also give a stronger molecular ion peak. Chemical ionization, field ionization, and desorption...

mass analyzers: overview

Mass Analyzers and Ion Separation

Mass analyzers separate ions by their mass-to-charge ratio, or m/z, in a mass spectrometer. After a sample is vaporized in the ionization chamber, it is hit with a high-energy electron beam. This creates a radical cation and also produces neutral molecules, radicals, and cations. Negatively charged accelerator plates then push the cations into the mass analyzer, where they are sent on to the detector. Several mass analyzer designs are commonly used. These include magnetic sector,...

mass analyzers: common types

Quadrupole, TOF, and Ion Trap Analyzers

Quadrupole, time-of-flight, and ion trap mass analyzers each separate ions in a different way. They are common tools in mass spectrometry and help sort ions by their mass-to-charge ratio, or m/z. A quadrupole mass analyzer uses four cylindrical metal rods arranged in a diamond shape. The rods carry a direct current, or DC, voltage and a radio-frequency AC voltage. Ion motion depends on the field strength, so only ions with a certain m/z resonate and reach the detector at that setting. This...

high-resolution mass spectrometry (hrms)

Mass Accuracy in HRMS Analysis

High-resolution mass spectrometry separates ions by very small differences in mass. This matters because atomic masses are not always exact whole numbers, even though they are often rounded for simple calculations. Atomic mass is usually estimated by adding the masses of protons and neutrons. In reality, the proton and neutron do not have exactly the same mass. That creates small differences when atomic masses are compared to the simplest hydrogen atom. Helium, for example, is made of 2...

mass spectrometry: complex analysis

Hyphenated Mass Spectrometry Methods

Mass spectrometry can be paired with separation methods to study complex mixtures. This combination is called a hyphenated method. It helps when a pure mass spectrum is too hard to read because a mixture causes too much fragmentation and too many overlapping signals. GC-MS is one common hyphenated method. GC stands for gas chromatography, which separates volatile, thermally stable compounds in narrow capillary columns before they enter the mass spectrometer. This approach is widely used in...

tandem mass spectrometry

Tandem mass spectrometry uses two or more mass analyzers in series to improve selectivity and lower chemical noise during analyte detection. A set of analyzers separated by an interaction cell lets the instrument break ions apart and study the fragment ions that form. Fragmentation happens in the interaction cell and can be caused in several ways. Collision-induced dissociation, or CID, uses inert gases such as nitrogen, argon, or helium. Other methods include surface-induced dissociation...

gas chromatography&ndash;mass spectrometry (gc&ndash;ms)

How GC-MS Separates and Identifies Compounds

Gas chromatography-mass spectrometry (GC-MS) separates compounds in a mixture and then identifies them. A gas chromatograph first splits the mixture into its parts. A mass spectrometer then analyzes each part on its own to determine molecular masses and molecular structures. The gas chromatograph uses a long, narrow capillary column. The inner wall of the column has a polysiloxane coating. This coating serves as the stationary phase. It has a high boiling point, low viscosity, and low polarity.

inductively coupled plasma&#8211;mass spectrometry (icp&#8211;ms): overview

inductively-coupled-plasmamass-spectrometry-icpms-overview

ICP-MS Sample Ionization and Detection

ICP-MS uses an inductively coupled plasma torch to turn samples into ions for mass analysis. Solid samples are first dissolved and volatilized before they enter the hot argon plasma. Solution samples are nebulized, which means they are converted into a fine spray, and then passed through the same plasma. Inside the plasma, the analytes break apart. Their atoms become positively charged ions, along with some molecular species. These positive ions are sent to the mass spectrometer, where they...

inductively coupled plasma-mass spectrometry (icp-ms): interferences

inductively-coupled-plasma-mass-spectrometry-icp-ms-interferences

ICP-MS Signal Interference Sources and Fixes

Inductively coupled plasma-mass spectrometry (ICP-MS) is a sensitive method for elemental analysis, but its spectra can be affected by interferences. These interferences can make the mass signal less accurate, even when the instrument is working well. Spectroscopic interferences happen when ions in the plasma have the same mass-to-charge ratio, or m/z, as the analyte ion. This group includes isobaric interferences, polyatomic ion interferences, and refractory oxide ion interferences. Isobaric...

key terms and concepts

Learn how tandem mass spectrometry uses CID, SID, ECD, PID, and scan modes like product-ion, precursor-ion, and neutral-loss scans to analyze fragment ions.

MS/MS Scan Modes and Fragment Ions | JoVE K12

analytical chemistry

JoVE Core Analytical Chemistry simplifies complex chemical principles by breaking them down into clear, engaging animations, making topics from SI Units to NMR spectroscopy more accessible and straightforward. Additionally, the scientist-in-action videos highlight the application of these concepts in real-world research conducted in laboratories globally.

MS/MS Scan Modes and Fragment Ions

Description

Transcript

Tags