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Conceptualization and Analytical Performance of a New ESI-MS Interface for
Structures for Lossless Ion Manipulations (SLIM)
Tsung-Chi Chen, Ian K. Webb, Marques B. Harrer, Spencer A. Prost, Randolph V. Norheim, Brian L. Lamarche, Xinyu Zhang, Jonathan T. Cox, Sandilya Garimella, Yehia M. Ibrahim,
Keqi Tang, Aleksey V. Tolmachev, Erin S. Baker, Gordon A. Anderson and Richard D. Smith
Pacific Northwest National Laboratory
Introduction
DC
DC
RF+DC
What are Structures for Lossless Ion Manipulations (SLIM)?
SLIM devices use RF and DC fields to manipulate ionsThe manipulations include moving forward/backward, turning, switching, mobility separations, etc.The planar surfaces are readily fabricated using printed circuit board (PCB) technologies
Applications of SLIM include extended sequences of manipulations, that involve separations, reactions, storage, accumulation, etc.
The Need for Efficient transfer of Ions to SLIM
Need to avoid ion losses upon injection of ions to SLIM devices
HPIF to SLIM interface
HPIF/IF to SLIM interfacefor larger reception area andbetter filed continuity to SLIM
ESI
SLIMExit Ion Funnel
MSy
z
Interface Ion Funnel
25 mm
ESI
Exit Ion Funnel
MSInterface Ion Funnel
25 mm
SLIM
4 ‐ 6 mm
Focusing Lens
New interface
SLIM interface design and simulation
General conditions for RIF simulation (SIMION):Pressure: 4 torr N2 (Statistical Diffusion Simulation Model)Charged particle mass: m/z 50-2000
y
z
x
Rectangular Ion Funnel
Conventional Ion Funnel25 mm
25 mm
5 mm
5 mm
35 mm
DC + RF
DCGuard electrodes
Central rung electrodes
SLIM
Simulations
RF confinementConditions:
RF frequency: 750 kHz
RF amplitude: varied from 60 to 300 Vpp
Guard DC bias :4 V for SLIM0 V for RIF
DC gradient at central electrodes: 20 V/cm
ObservationsSimulation result shows most ions were transferred through rectangular electrodes to SLIM with a wide range of RF amplitudes.High RF amplitude results in better radial confinement essentially focusing high m/z ions.
RF = 60 Vpp
RF = 300 Vpp
y
z
m/z 350m/z 2050
Guard DC bias
Conditions:DC gradient: 20 V/cmRF: 750 kHz, 61.5 VppGuard DC bias:
SLIM: 5 VRIF: varied
ObservationsHigh guard DC bias leads ions dispersed in y directionLow guard DC bias leads ions dispersed in x direction
VRIF_Bias = ‐5 V
VRIF_Bias = +3 V
y
z
x
z
VRIF_Bias = 0 V
+3 V
0 V
‐5 V
Simulations
DC gradient along central rung electrodes
Conditions:RF: 750 kHz, 120 VppGuard DC bias:
5 V for SLIM1 V for RIF
DC gradient: varied
Observation:Less ion diffusion in radial direction was found with higher DC gradient along the RIF central electrodes.
June 19 20147
E = 5 V/cm
E = 10 V/cm
E = 20 V/cm
y
z
Simulations
Design and Fabrication
PCB-based RIF electrode designCentral (y) electrodes - RF + DC gradientGuard (x) electrodes - DC bias + DC gradient
25 mm5 mm
Central rung (y) electrodes
Guard (x) electrodes
0.0E+00
4.0E+04
8.0E+04
1.2E+05
30 80 130 180 230 280
Intensity
rf amplitude (Vpp)
622.17
1221.9
0.E+00
2.E+03
4.E+03
6.E+03
8.E+03
30 80 130 180 230 280
Intensity
rf amplitude (Vpp)
1821.72721.2(Ix10)
Initial RIF Characterization
RF confinementExperimental conditions
Pressure : 4 torrRF Freq.: 810 kHzRF Amplitude: variedGuard DC bias:
RIF In: 3.2 VRIF Out: 1.9 V
RIF DC gradient: 9 V/cm
Observations:m/z discrimination was observed for low RF amplitude between 60 and 110 Vppon RIFOptimal RF amplitude >110 Vpp is suggested for RIF
70 Vpp
110 Vpp
(a)
(b)
RIF In
RIF Out
Guard DC biasExperimental conditions
RF: 810 kHz, 160 VppPressure: 4 torrGuard DC bias:
varied Electrode dimensions
Inlet: 25.4 x 25.4 mmOutlet: 5 x 5 mm
RIF DC gradient: 9 V/cm
Observations:DC bias at inlet is less sensitive to the voltage change than that at outlet due to the different spacing of electrodesOptimal DC bias ranges of -10~+10 V for RIF inlet and +1~+3 V for outlet.
0%
20%
40%
60%
80%
100%
120%
‐40 ‐20 0 20 40 60
Ion Ab
unda
nce
dc bias (V)
90%
dispersed in X‐direction
dispersed in Y‐direction
0V
0%
20%
40%
60%
80%
100%
120%
‐5 0 5 10
Ion Ab
unda
nce
dc bias (V)
dispersed in X‐direction
dispersed in Y‐direction
1.9V90%
Initial RIF Characterization
(a)
(b)
0.06
0.08
0.1
0.12
0.14
0.16
0.18
0.2
0.22
0 2 4 6 8 10 12 14 16 18 20
Curren
t (nA
)
E (V/cm)
RIF DC gradientExperimental conditions
RF: Freq.: 750 kHzAmp.: 160 Vpp
Pressure : 4.1 torrDC gradient: VariedGuard dc bias:
Optimized based on the current measurement
ObservationRIF DC gradient >10 V/cm for optimal ion transmission for 3” RIF
9.3 V/cm
Initial RIF Characterization
RIF
Instrumental configuration used & ion optics design
4 torr 4 torr
9 V/cm
14 ‐20 V/cm
760 torr 1E‐8 torr
3” (76.2 mm) 15” (381 mm)
Initial RIF-SLIM Characterization
TOF‐MS
SLIM
0.0E+00
1.0E+04
2.0E+04
3.0E+04
4.0E+04
5.0E+04
6.0E+04
0 50 100 150 200 250 300 350
Intensity
RF amplitude (Vpp)
1521.82722.2 ( x50)
0.0E+00
5.0E+04
1.0E+05
1.5E+05
2.0E+05
2.5E+05
0 50 100 150 200 250 300 350
Intensity
RF amplitude (Vpp)
622.2 ( x2)1221.9
RF amplitudeConditions:
Guard DC bias :SLIM: 15 V forRIF In: 3.2 VRIF Out: 1.9 V
Central electrode DC gradient: SLIM: 14 V/cmRIF: 9.3 V/cm
RF frequency: RIF&SLIM: 810 kHz
RF amplitude: SLIM: variedRIF: 160 Vpp
120 Vpp
160 Vpp
m/z
m/z
Initial RIF-SLIM Characterization
(a)
(b)
140 Vpp
180 Vpp
SLIM DC gradientExp. Conditions
RF: Frequency: 810 kHzRIF amplitude: 160 VppSLIM amplitude: 200 Vpp
Pressure : 4 torrDC gradient:
RIF: 9.3 V/cmSLIM: Varied
Guard DC bias:Optimized based on the TIC measurement
Observationm/z discrimination was found for high m/z ions (1522-2422) with low DC gradient (>13 V/cm) on RIF-SLIM device
0.0E+00
4.0E+04
8.0E+04
1.2E+05
1.6E+05
0 5 10 15 20 25
322.2622.2922.011221.9
0.0E+00
1.0E+04
2.0E+04
3.0E+04
4.0E+04
0 5 10 15 20 25
1521.81821.62121.52422.3 (x50)
13 V/cmm/z
m/z
Initial RIF-SLIM Characterization
(a)
(b)
RIF-SLIM Performance
Sensitivity Exp. Condition
Pressure: RIF-SLIM: 4.00 torr
Guard DC bias, DC gradient& RF were optimized based on the characterization results.Solution electrosprayed:
Agilent ESI-L tune mixture
Observation:~2x intensity increase by RIF-SLIM
0.0
5.0x105
1.0x106
1.5x106
2.0x106
2.5x106
Inte
nsity
-2.5x106
-2.0x106
-1.5x106
-1.0x106
-5.0x105
0.0
322(2.3 X)
622(1.63 X)
922(1.9 X)
1222(2.5 X)
1522(1.5 X) 1822
(1.4 X)
IFT to SLIM interface
IFT/RIF to SLIM interface
0 1 2 3 4 5 6 7 8 9 10 110.0
2.0x107
4.0x107
6.0x107
TIC
Time (hour)
StabilityNo observable intensity decrease during the 11-hour stability test
Syringe pump stopped
Averaged from 0 to 11 hours
Agilent ESI‐L low concentration tuning mix
RIF-SLIM Performance
Set nESI voltageat 2.5 kV
0 500 1000 1500 2000 2500 30000.0
5.0x105
1.0x106
1.5x106
Inte
nsity
m/z
2122322
622
922
1222
1522
1822
Performance evaluation on RIF-SLIM
June 19 2014 17
200 4000.0
5.0x105
1.0x106
1.5x106
2.0x106
2.5x106
3.0x106
467, TAA8
411, TAA7
354, TAA6299,
TAA5
242, TAA4
Inte
nsity
m/z
186, TAA3
0 200 400 600 800 10000.0
5.0x104
1.0x105
1.5x105
2.0x105
(1) 354, [Bradykini+3H]3+
(2) 387, [Kimptide+2H]2+ (3) 433, [Angiotensin I+3H]3+
(4) 450, [Substance P+3H]3+
(5) 524, [Angiotensin II+2H]2+
(6) 530, [Bradykini+2H]2+
(7) 558, [Neurotensin+3H]3+
(8) 587, [Renin+3H]3+
(9) 674, [Substance P+2H]2+
(10) 712, [Melittin+4H]4+
(11) 769, [Fibrinopeptide A+2H]2+
(1)(4)
Inte
nsity
m/z
(2) (5)
(3)
(7)
(6) (8)(9) (10)
(11)
(a) (b)
(c) (d)
tetra‐n‐alkylammonium
600 800 1000 12000.0
2.0x105
4.0x105
6.0x105
8.0x105
1.0x106
1.2x106
1.4x106
1.6x106
1.8x106
Cytochrome c Deconvolution: 12253
+10+11+12
+13
+16
+14
+15+17
+18
+19
Inte
nsity
m/z
+20
600 800 1000 12000
1x105
2x105
3x105
4x105
5x105
+7+8+9
Inte
nsity
m/z
+14
+13
+12
+11
+10
UbiquitinDeconvolution: 8566
Conclusions
A Rectangular Ion Funnel (RIF) was designed, guided by ion simulations, including PCB-based circuit and electrode designs
The RIF and its interface with SLIM was characterized to determined the optimal operating parameters, including RF amplitude, Guard DC bias and central rung electrode DC gradients
The results of performance evaluation on RIF-SLIM indicated ~2x sensitivity increase, and displaying extended operation with high stability and without significant m/z discrimination over 300-2700 m/z range
Support
NIH GMS Biomedical Technology Proteomics Research ResourceDOE Office of Biological and Environmental ResearchPNNL Laboratory Directed R&D
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