Triple quadrupole mass spectrometers use three quadrupole mass analyzers in tandem. Ions pass through the first quadrupole (Q1) where they can be filtered for a specific m/z. They then enter the collision cell (Q2) where they can be fragmented via collisions with gas. The resulting product ions are analyzed by the third quadrupole (Q3), which can scan a range of m/z or filter for a specific m/z. This allows different scan modes like precursor ion scans, neutral loss scans, and selected/multiple reaction monitoring for applications like proteomics and metabolomics. Triple quadrupole mass spectrometers provide high sensitivity and selectivity for quantitative and qualitative analysis

1. Quadrupole mass analyzer
HOW IT WORKS
TRIPLE QUADRUPOLE MASS SPECTROMETER
MIDHUNA (P21SH202)

2. Mass Spectrometry
A technique for measuring and analyzing molecules, that involves introducing enough
energy into a (neutral) target molecule to cause its ionization and disintegration. The
resulting primary ions and their fragments are then analyzed, based on their mass/
charge ratios, to produce a "molecular fingerprint
Chromatography
GC/LC
IONIZATION
SOURCE
MASS ANALYZER DETECTOR
ESI Quadrupole Electron Multiplier
MALDI Time-Of-Flight Faraday Cup

3. QMA is one type of analyzer used in MS
Quadrupole mass filter
Four cylindrical rods are parallel to each other
Opposing rod pair is connected together
electrically
Mass Analyzer: Quadrupole (Q)

4. PRINCIPLE
By applying DC and AC, Potential generated will cause
the movement of ions
As they move positive ions will migrate – ve electrode and
negative ions migrate to the +ve electrode, and they will
never get mixed up
Ions travel through the quadrupole, on the produced
electric field, only ions of a particular m/z will be focused
on the detector (Resonant ion), all the other ions will be
deflected into the rods. (non-resonant ion)

5. If the applied voltage is composed of a DC voltage U and a radiofrequency (RF) voltage V with the
frequency ω the total potential Φ is given by,
Φ= U + V cos ωt
The path stability of a particular ion is defined by the magnitude of the RF voltage V and by the ratio
U/V.
Reducing U relative to V, ( RF>DC), smaller m/z ion bombard to wall and distance to the detector will
increase and larger ion bombard less, moves faster so increasingly wider m/z range can be transmitted
simultaneously.
If RF<DC, smaller ion hit the detector first

6. Path stability of a particular ion is determined by- varying the amplitude of the voltages (AC/DC )

7. TRIPLE QUADRUPOLE MASS ANALYZER
 analyzer in tandem
 three sets of quadrupole analyzers are used in sequence

8. Q1 can scan across a range of m/z values or selectively filter ions of a selected m/z.
Q2 -collision cell - fragment the selected ions from Q1.
The product ions formed scanned through Q3, to obtain a mass spectrum or Q3 can be fixed
in order to monitor a particular ion.
Combination of fixed or scanning modes of Q1 and Q3 determine the type of scan
performed

9. SCAN MODES

10. Product ion scans also known as daughter ion scans
• Q1 is set to allow only the transmission of one m/z • The parent ion collides with Argon gas
in Q2 to create fragment or product ions • Product ions are scanned through Q3 - Once the
product ions are recorded, Q1 can then fix on a new m/z and the process repeated.
Applications:
 Bottom-up proteomics approach, the sequence of many peptides eluting off a
chromatographic column can be sequenced.
 Targeted Metabolomics

11. Precursor ion scan –Q3 is set to allow only a fragment ion of one m/z to pass
•Q1 is scanned across the entire m/z range of the analyzer.
•The precursor ions subsequently pass through Q2 for CID.
•Q3 is kept fixed such that only product ions of a specific m/z are filtered through the
quadrupole.
 Precursor ion scanning allows one to determine the m/z of all precursor ions that have the
same product ion.
 This is valuable in proteomics when one wants to identify all peptides that may have the
same functional group.

12. Precursor ion scans are used for screening experiments where a group of compounds all gives
the same fragment ion
Eg 1: m/z 216 = signature immonium ion for phosphotyrosine
Precursor ion scan allows identification of all peptides containing phosphotyrosine

13. Eg 2: identification of fragment of m/z=84 from different compounds

14. Neutral loss scan –
•Track ions before and after the loss of a neutral group.
•Both Q1 and Q3 are scanned simultaneously over the entire m/z range but with Q3 offset
from the Q1 by an amount that corresponds to the loss of a neutral fragment from the ion.
•all precursors that undergo the loss of the same neutral fragment can be monitored.
Application: PTM

15. Eg: Performing low energy CID on peptides
that are phosphorylated will often result in the
loss of phosphoric acid (H3PO4, m/z ¼ 98)
from the parent ion, identification of peptides
with phosphorylated serine or threonine

17. Selected reaction monitoring –
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.
Thus, specific signature fragment ions originating from a compound of known mass can be
monitored.

18. Eg:-
Orphenadrine is an anticholinergic drug of the ethanolamine
antihistamine class. Q1 is set to allow only the transmission
of Orphenadrine m/z 269.9 - Q3 is scanned only to detect
m/z 181.1 +/- 0.3

19. SPECIFICATION
Mass range 10-4000 dalton(amu)
Resolution, typically 1000
Scan rate 5000dalton/min
Accuracy .1-.2dalton

20. Applications
Compositional analysis of gas and volatile liquids
Mainly used in residual gas analysis
Used in LC-MS and GC-MS
Both qualitative and quantitative
Advantage
Compactible and reliable
Law cost analytical tool
Excellent stability over long periods of time
Disadvantage
Low resolution, high sensitivity
Only one m/z ratio can be obtained at a time
Broader m/z obtained only after long scanning period
Not suited for pulsed ionization method

21. REFERENCES
1. Mass Analyzers and Mass Spectrometers Anthony M. Haag
2. Jürgen H. Gross Mass Spectrometry
3. Lovrić, Josip - Introducing proteomics _ from concepts to sample separation, mass spectrometry and
data analysis-Wiley-Blackwell (2012)

22. Read to explore. Thank you