Quadrupole mass spectrometer, QMS
QMS is the most common mass spectrometry instrument with outstanding quantitative ability, accounting for the vast majority in GC-MS.
Simple structure, low cost, and easy maintenance;
The quantitative ability of SIM function is strong, and it is an instrument and equipment used in most detection standards.
Lack of cross polarity ability and insufficient qualitative ability;
Low resolution (unit resolution), with interference from isotopes and other ions with m/z approximation;
Slow speed and low quality limit (less than 1200u).
Time of Flight Mass Spectrometer, TOFMS
TOFMS is the fastest mass spectrometer suitable for LC-MS applications.
It has good resolution, which is helpful for qualitative analysis of the difference between the m/z approximate ion and the ESI spray ion source;
Fast speed, with 2-100 high-resolution full scan (such as 50-2000u) spectra per second, suitable for fast LC systems (such as UPLC);
High quality limit (6000~10000u).
No string pole function, which limits further qualitative ability;
The selling price is higher than QMS;
More precise and requires careful maintenance.
Triple quadrupole mass spectrometer, QQ
QQ mass spectrometry provides a cascade function for quadrupole mass spectrometers while retaining the strong quantitative ability of QMS, enhancing the qualitative ability of mass spectrometry. It is often used as a confirmation detection method for QMS in detection standards.
Has string pole function and strong qualitative ability;
Very good quantitative ability, MRM has a higher signal-to-noise ratio than QMS's SIM;
It is a commonly used QMS result confirmation instrument;
In addition to the general sub ion scanning function, QQQ also has functions such as SRM, MRM, mother ion scanning, and Neutrality loss (ion trap not working);
Studying the structure of characteristic groups is of great help.
Insufficient resolution and susceptibility to ion interference from m/z approximation;
High selling price;
Careful maintenance is required.
Quadrupole ion trap, QTrap
Technically speaking, auxiliary RF has been added to the quadrupole of traditional QQ, which can be selectively excited; Or in terms of functionality, it provides QQ with multi-level cascade functionality.
Simultaneously equipped with MRM, SRM, neutral loss, and multi-level cascade functions, it is very suitable for structural analysis of unknown samples.
The resolution is still a bit low.
Ion trap mass spectrometer, ITMS
Ion trap mass spectrometer is the simplest tandem mass spectrometry commonly used for structural identification.
Cost lower than QQ, compact in size;
Having multi-level cascade capability, suitable for qualitative research in molecular structure, able to provide local structural information of molecules, better than QQ.
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