Waters

Triple Quad Mass SpectrometerQ1 Q2 Q3Q0

RF only Collision Cell

Scanning RF/DC

ScanningRF/DC

RF only

• Q1 and Q3 are standard mass filter quadrupoles.– The can scan masses sequentially (e.g. 50 to 500 amu)– The can be used to select a single mass.

• Q2 is an RF only quadrupole that is in a gas filled chamber. – Q2 is the “collision cell” where mass fragmentation occurs. – Q2 does not filter ions. It accepts all ion sent to it by Q1

and passes all ions formed by collision to Q3 to be sorted.

vs. Tandem-in-Time

(Quadrupole Ion Trap)

(Triple Quadrupole)

Tandem-in-Space

triple

GC/triple

Triple quad modes of operation

Triple Quads…• In scanning mode 99% ions lost between the rods.

– Poorer full scan sensitivity

• In SIM mode 100% of selected ion reaches detector.– Makes them highly sensitive and great for

quantitation!

• Mass resolution typically limited to “unit” (+/- 0.2 amu)

• Fragmentation is controlled by the energy ions have when they enter the collision cell.– Higher energy >> greater fragmentation.

Hybrid Instruments

• Typically in the same configuration as a triple quadrupole instrument.

• On the Qtrap Q3 is the hybrid quadrupole dubbed a “linear ion trap” or LIT.

• Q3 can function as a quadrupole OR an LIT.

Q0 Q1 Q2 Q3

Applied Biosystems 3200 Qtrap System

LIT Scanning

Radial Trapping

AxialTrapping

Auxiliary RFRamped….

Exit Lens with Grid

Main RFRamped…

Q2

…simultaneously Ramp EXB

Radial Trapping

Advantages of LIT vs. IT• Has a larger “volume” so it can be filled with more ions

before exhibiting space charge effects.

• Ions are formed outside the trap, so it is not limited by the 1/3 rule.

• Can perform MS/MS/MS experiments by selecting an ion and fragmenting it using the spillover collision gas. (1/3 rule applies here…)

Modes of Operation• Triple Quads and Ion Traps

– Full Scan (LC/MS)– MRM (Multiple Reaction Monitoring)– Product Ion Scan (PI)

• Exclusively Triple Quad– Constant Neutral Loss – Precursor Ion Scan

• Exclusively Ion Trap– MSn

H

Y

B

R

I

D

S

Multiple Reaction Monitoring (MRM)

• Q1 Selects an [M+H]+

• Q2 fragments the selected ion.• Q3 monitors only one daughter ion

Q0 Q1 Q2 Q3

N2 CAD GasPrecursor ion selection

Ion accumulation

Fragmentation

Exit lensSteps MS2: 1 2 3 &4

MRM

• Only the daughter ion reaches the detector. • Sensitivity of MRM is a function of how much of

the daughter ion is produced.• The parent ion fragmentation to daughter ion is

commonly referred to as a “transition”

Q0 Q1 Q2 Q3

N2 CAD GasPrecursor ion selection

Ion accumulation

Fragmentation

Exit lensSteps MS2: 1 2 3 &4

Example MRM Data

• Many transitions can be stacked together in a method.• The instrument will monitor each pair for a short time.• MRM is analogous to SIM on a GC/MS only more

compound specific.

Oxycodone: (316.2 241)Parent : 316.2

Daughter : 241

Result of one MRM cycle of 130 drugs.

Product Ion Scanning

• Q1 selects a parent ion.• Q2 fragments the selected ion• Q3 traps then scans out all fragment ions.

Q0 Q1 Q2 Q3

N2 CAD Gas linear ion trap3x10-5 Torr

Precursor ion selection

Ion accumulation

Fragmentation

Exit lensSteps MS2: 1 2 3 &4

Product Ion Scan

• Selection of a single parent ion by Q1 allows separate product ion scans for coeluting compounds to be easily generated.– Provided they don’t have the same mass…

Q0 Q1 Q2 Q3

N2 CAD Gas linear ion trap3x10-5 Torr

Precursor ion selection

Ion accumulation

Fragmentation

Exit lensSteps MS2: 1 2 3 &4

Example EPI Data

• Oxycodone (316.2) is selected by Q1.• Q2 fragments oxycodone• Q3 operating as an LIT traps all the

fragments, and the scans them out.• “Enhanced” means using the LIT.

Linking MRM and EPI• MRM is an excellent survey method.

– Allows for stacking of many transitions– Relatively fast* cycle time

• EPI is an excellent for qualitative identification– Parent ion linked fragmentation pattern– Many fragments that can be library matched.

• An ideal qualitative method would use MRM to look for drugs, and EPI to confirm them.

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