Transmission Mode Ion/Ion Reactions in the Q0 cell of a Hybrid Triple Quadrupole/Linear Ion Trap Instrument

1
Transmission Mode Ion/Ion Reactions in the Q0
cell of a Hybrid Triple Quadrupole/Linear Ion
Trap Instrument

• Joshua F. Emory and Scott A. McLuckey
• Department of Chemistry, Purdue University, West
  Lafayette, IN 47907

2
Overview

• The possibility of performing transmission mode
  ion/ion reactions in the higher pressure RF only
  Q0 quadrupole is being investigated.
• The ability to perform these proton transfer
  charge reduction or charge inversion reactions in
  Q0 would enable multiple ion/ion reactions to be
  performed in separate regions of the instrument,
  perhaps by doing a preparatory reaction in Q0 and
  a second reaction in Q2.
• The drawback to performing ion/ion reactions in
  the Q0 cell is that neither the analyte nor the
  reagent ion can be isolated prior to introduction
  into the Q0 quadrupole and the subsequent ion/ion
  reaction.

3
Introduction

• Proton transfer ion/ion reactions have been used
  for protein charge reduction, to concentrate the
  charge envelope of proteins as well as to invert
  the polarity of peptides within the mass
  spectrometer.
• These reactions can be performed by storing the
  reagent in the Q0 cell and passing the analyte
  through the Q0 cell or by storing the analyte in
  the Q0 cell and passing the reagent through the
  Q0 cell.

4
Experimental

• Perfluoro-1-octanol (PFO), the charge reduction
  reagent, solution consisted of a aqueous solution
  of 200 to 400 µM of reagent in (48.548.53)
  methanol, water, and ammonium hydroxide.
• Protein electrospray solutions were diluted to
  10 to 20 µM in (49492) water, methanol, and
  acetic acid.
• The charge inversion reagents, polypropylenimine
  diamino-butane (DAB) dendrimers and
  polyamidoamine (PAMAM) dendrimers were made in
  aqueous 1-2 acetic acid and in aqueous 1-2
  ammonium hydroxide, respectively.
• Bradykinin electrospray solutions consisted of an
  aqueous solution of 10 µM concentration of
  peptide in (49492) methanol, water, and
  ammonium hydroxide.

5
Modified Q-Trap 2000/4000
Auxiliary RF applied for ion parking
Dual ESI sources
Aux AC
N2 CAD Gas
RF
Exit lens
Orifice
Skimmer
IQ1
ST
IQ2
IQ3
Deflector
Triggered HV
Triggered -HV
Ion/Ion Reaction
Detector

• Transmission mode reactions in Q0 can be
  performed by
• By storing the reagent ion in Q0, and
  transferring the desired analyte ion through the
  Q0 cell.
• By storing the desired analyte ion in Q0, and
  transferring the reagent ion through the Q0 cell.

6
Mutual Storage Mode Ion/Ion Reactions in a LIT
end lens
end lens
LIT
Trapping Anions
Trapping Cations
RF

• Mutual storage of oppositely charged ions
  requires application of
• auxiliary RF to the end lenses of the
  quadrupole.

Transmission Mode Ion/Ion Reactions in a LIT
Passing Anions
TrappingCations
DC
Trapping Anions
Passing Cations
DC

• Does not require application of auxiliary RF to
  end lenses.
• Performing ion/ion reactions in Q0 allows further
  ion/ion reactions
• or CID to be performed in the Q2 or Q3 cell of
  the instrument.

7
Transmission Mode Charge Inversion

• Involves transfer of multiple protons to an
  analyte or the removal of multiple protons from
  an analyte.
• Charge inversion of an analyte species separates
  the ionization polarity of the analyte from
  analysis polarity.
• Separation of ionization polarity from analysis
  polarity allows interrogation of an analyte in
  both polarities, increasing the amount of
  information that can be obtained from the analyte
  via dissociation methods such as CID and ETD.

8
Charge Inversion Process Multiple Proton Transfer
Polyamidoamine (PAMAM) Dendrimer
Peptide Ion (Bradykinin)
1,4-Diaminobutane (DAB) Dendrimer
9
Charge Inversion of Bradykinin -1 in Q0
100
100
Bradykinin -1
Gen 4 DAB 6

50
50
1100
900
300
700
500
1000
800
900
1100
700
1e7
Passing bradykinin -1 through Q0 for 200 ms
Bradykinin 2
Bradykinin 1
5e6
DAB 6
DAB 5
DAB 3
DAB 4
1500
700
500
300
1300
900
1100
m/z
10
Charge Inversion of Bradykinin 1 in Q0
100
100

PAMAM
50
50
Bradykinin 2
Bradykinin 1
2000
0
1000
500
1500
700
300
900
500
1100
8e6
Passing bradykinin 2/1 through Q0 for 1 s
Bradykinin -1
PAMAM -4
PAMAM -5
4e6
PAMAM -6
Bradykinin -1
1200
1000
800
600
400
m/z
11
Ion Parking in Q0

• Application of a Dipolar AC frequency to one pair
  of rods in a quadrupole
• Analogous to low amplitude CID
• Parking has previously been performed in 3D ion
  traps and in the Q2 cell of 2D traps.

12
Types of Ion Parking
Quadrupole Rod

• A) SFOR ion parking where a single-frequency, on
  resonance, low amplitude ac signal is applied to
  an opposing quadrupole rod set.
• B) HALF parallel ion parking where a
  high-amplitude, low-frequency ac signal is
  applied to an opposing quadrupole rod set.

A.
f0,z (21/2/ro2 O)(zV/m) c(zV/m)
B.
?z
O
13
Ion/Ion Reaction of Insulin with PFO in Q0
100
100
5
Insulin
-1
PFO perfluoro-1-octanol

6
50
50
CF3(CF2)6CH2OH
4
500
1500
1100
900
700
1300
1700
300
500
400
600
200
2e6
No Ion Parking
1e6
4e7
Insulin 4
SFOR Ion Parking of Insulin 4 f 32.633 kHz, 4
Vp-p
2e7
Insulin 3
3000
1000
3400
1400
1800
2200
2600
m/z
14
Parallel Ion Parking of a Protein Mixture in Q0
150
U2
100
50
I2



600
U3
Insulin I Ubiquitin U Equine Cyt. C
E Bovine Cyt. C B Myoglobin M Lysozyme L
B4
I2
400
M6
L5
M5
E4
200
L4
E3
B5
E5
B3
I3
U2
U4
0
2000
2400
2800
3600
4400
3200
4000
m/z
15
Results

• Charge reduction by proton transfer with or
  without ion parking of the desired charge state
  can be performed in the Q0 cell.
• Charge inversion of bradykinin -1 to 2/1 and
  charge inversion of bradykinin 2/1 to
  bradykinin -1 can also be performed in the Q0 RF
  only quadrupole.
• The use of Q0 as a reaction cell enables two
  reactions to be performed in rapid succession in
  separate regions of the instrument. For example,
  two ion/ion reactions could be performed on an
  analyte using transmission mode experiments,
  eliminating the need for auxiliary RF on the end
  lenses of the Q0 or the Q2 quadrupoles.

16
Conclusions

• Transmission mode proton transfer charge
  reduction reactions can be performed in the Q0
  quadrupole, eliminating the need for application
  of auxiliary RF on the end lense of the Q0
  quadrupole.
• Charge inversion of bradykinin from negative to
  positive and from positive to negative in the RF
  only Q0 cell has been demonstrated.
• Separates analysis polarity from ionization
  polarity
• Performing ion/ion reactions in Q0 allow further
  ion/ion reactions to be performed in the Q2
  and/or Q3 cell of a hybrid linear ion trap.
• HALF and SFOR methods of ion parking have been
  successfully demonstrated in the RF only Q0 cell.

17
References

• M. He, J.F. Emory, S.A. McLuckey, Anal. Chem., 77
  (2005) 3173-3182.
• M. He, S.A. McLuckey, J. Am. Chem. Soc., 125
  (2003) 7756-7757.
• P. A. Chrisman, S. J. Pitteri, S. A. McLuckey,
  Anal. Chem., 78 (2006) 310-316.
• P.A. Chrisman, S.J. Pitteri, S.A. McLuckey, Anal.
  Chem., 77 (2005) 3411-3414.

18
Acknowledgments

• MDS SCIEX
• NIH GM 43572
• McLuckey Group