What are the tandem methods of tandem mass spectrometry

There are many types of tandem mass spectrometry, commonly used are quadrupole analyzers (Q for short), followed by ion trap analyzers and time-of-flight analyzers (TOF).

In order to increase the structural information, most of them use mass analyzers with tandem mass spectrometry functions, and there are many tandem methods, such as Q-Q-Q, Q-TOF, etc
.

The main tandem methods of tandem mass spectrometry have many tandem methods of mass spectrometry, both spatial tandem and time tandem
.

The spatial tandem type is divided into magnetic fan series, quadrupole series, hybrid series and so on
.

If B represents the sector magnetic field, E represents the sector electric field, Q represents the quadrupole, and TOF represents the time-of-flight analyzer, then the main ways of tandem mass spectrometry are: 1, space series magnetic sector series: BEB EBE BEBE and other quadrupole series: Q-Q-Q hybrid series: BE-Q EBE-TOF Q-TOF2, time series ion well mass spectrometer cyclotron resonance mass spectrometer Regardless of which way of series, there must be a collision activation chamber.
The specific ions separated from the primary MS are subjected to collision activation and then mass analysis by the secondary MS in order to obtain more information
.

Comparison of the advantages and disadvantages of 10 kinds of tandem mass spectrometry I.
Quadrupole mass spectrometer, QMSQMS is a common mass spectrometry instrument, with outstanding quantitative ability, and QMS accounts for the vast majority
in GC-MS.

Advantages: simple structure, low cost; Simple maintenance; Strong quantitative ability of SIM function; It is the instrument and equipment used in most testing standards
.

Disadvantages: no string pole ability, insufficient qualitative ability; Low resolution (resolution), presence of ion interference from isotopes and other m/z approximations; Slow speed; The upper limit of quality is low (less than 1200u
).

Second, time-of-flight mass spectrometer, TOFMSTOFMS is a faster mass spectrometer, suitable for LC-MS applications
.

Advantages: good resolution ability, helpful to qualitative and m/z approximate ions of the difference, can be well detected ESI electrospray ion source to produce multi-charge ions; Fast speed, 2 ~ 100 high-resolution full scans per second (such as 50 ~ 2000u) spectrogram, suitable for fast LC systems (such as UPLC); High upper limit of mass (6000~10000u); Disadvantages: No string pole function, limiting further qualitative ability; The price is higher than QMS; It is more precise and requires careful maintenance
.

Third, triple quadrupole mass spectrometer, Q-Q-QQ-Q-Q mass spectrometry to the quadrupole mass spectrometer in retaining the original quantitative ability of QMS, providing a cascade function, strengthen the qualitative ability of mass spectrometry, testing standards are often used as a means
of confirmation of QMS detection.

Advantages: there is a string pole function, strong qualitative ability; The quantitative ability is very good, and the MRM signal-to-noise ratio is higher than that of QMS SIM; Is a commonly used QMS result confirmation instrument; In addition to the general subion ion scanning function, Q-Q-Q also has SRM, MRM, parent ion scanning, Neutral loss (neutral loss) and other functions (ion trap is not OK) is of great help
to the structural study of characteristic groups.

Disadvantages: insufficient resolution, easy to be interfered with by m/z approximation of ions; Higher price; Requires careful maintenance
.

Fourth, quadrupole ion trap, QTrap technology, in the traditional Q-Q-Q quadrupole added auxiliary radio frequency, can do selective excitation; Or, in terms of functionality, provides the functionality
of multi-level cascades for Q-Q-Q.

Advantages: With mrIM, SRM, neutral loss and multi-stage cascade capabilities, it is very suitable for structural analysis of unknown samples
.

Disadvantages: The resolution is still a little
low.

Linear Ion Trap, an enhanced version of linear Ion Trap traditional 3D ion trap.
Advantages: Compared with traditional 3D ion traps, the sensitivity is more than 10 times higher; Multi-stage cascade mass spectrometry.
Disadvantages: Compared with Q-Q-Q, it is still impossible to do THE CHARACTERISTIC GROUP SCREENING FUNCTIONS SUCH AS MRM AND NEUTRAL LOSS.
Sixth, time-of-flight tandem mass spectrometry, QTOFQTOF with QMS as the mass filter and TOFMS as the mass analyzer
.

Advantages: can provide high-resolution spectra; Qualitative ability is better than Q-Q-Q; Fast for large molecular weight complex sample analysis in life sciences
.

Disadvantages: high cost; Requires careful maintenance
.

Trap TOF uses 3D ion traps as mass selectors and reactors, combining the multi-stage mass spectrometry capabilities of ion traps and the high resolution capabilities
of time-of-flight mass spectrometry.

Advantages: It has multi-stage cascade and high resolution capability at the same time, which is suitable for qualitative work of unknown samples, such as the characterization of glycoproteins
.

Disadvantages: Poor sensitivity to mixed samples due to ion trap capacity limitations; Weak
quantitative ability.

The quantitative ability of Sector MS magnetic mass spectrometry is stronger among the various mass spectrometry
.

It is now less used and is only used for the detection
of geological elements and trace dioxins.

Advantages: classic technology, mature, NIST and other MS libraries used instruments; Very good resolution (100k, m/&delta m FWHM) with less interference; The sensitivity is high and the quantitative ability is better
in various mass spectra.

Disadvantages: large volume and weight; The price is high; Slow speed; Complex maintenance and very expensive.


Ft-ICR-MS is said to be the noble in mass spectrometry, with good mass accuracy and no need to correct for
several months.

But the price is also expensive and chilling
.

Fourier transform mass spectrometers have higher resolution capabilities and are often used as equipment
for scientific research.

Advantages: can do multi-level cascade, good qualitative ability; High resolution; Good sensitivity; Disadvantages: large volume weight; High price; The speed is also slower; Maintenance is very expensive
.

10.
Electrostatic field Fourier transform mass spectrometry, Orbitrap advantages: high resolution, 60k~120kFWHM, high quality accuracy; Compared to FT-ICR, the price is slightly lower (~450kUSD); Disadvantages: can not do cascade alone; Resolution, sensitivity, and mass stability are still far from
the FT-ICR.