Advances in DART Instrumentation: Transmission Mode, Laser

Advances in DART Instrumentation: Transmission Mode, Laser

Advances in DART
Instrumentation: Transmission
Mode, Laser Ablation and
Mobility Separations
Facundo M. Fernández
School of Chemistry and Biochemistry. Georgia Institute of Technology. Atlanta,
Georgia, USA.
Fernandez Group 2011
Ambient MS
• Ambient MS refers to ionization techniques performed:
–
–
–
–
–
Atmospheric pressure
In the open-air, no enclosures
No restrictions on sample size and shape
Sample in its native state
Relatively soft ionization conditions
Fernandez Group 2011
Surface Sampling “Ambient” MS
Acronym
Name
AP-TD/SI
BADCI
DAPCI
DAPPI
DART
DBDI
DCBI
DEMI
DESI
DICE
EASI
ELDI
FAPA
IR-LAMICI
LADESI
LAESI
LDESI
LESA
LIAD-ESI
LMJ-SSP
LTP
MALDESI
ND-EESI
PESI
RADIO
REIMS
SwiFerr
Atmospheric Pressure Thermal Desorption-Secondary Ionization
Beta electron-assisted Direct Chemical Ionization
Desorption Atmospheric Pressure Chemical Ionization
Desorption Atmospheric Pressure Photo-Ionization
Direct Analysis in Real-Time
Dielectric Barrier Discharge Ionization
Desorption Corona Beam Ionization
Desorption Electrospray/Metastable-Induced Ionization
Desorption Electrospray Ionization
Desorption Ionization by Charge Exchange
Easy Ambient Sonic-spray Ionization
Electrospray-assisted Laser Desorption Ionization
Flowing Atmospheric Pressure Afterglow
Infrared Laser Ablation Metastable-induced Chemical Ionization
Laser-Assisted Desorption Electrospray Ionization
Laser Ablation Electrospray Ionization Mass Spectrometry
Laser Desorption Electrospray Ionization
Liquid Extraction Surface Analysis
Laser-Induced Acoustic Desorption-Electrospray Ionization
Liquid Micro Junction-Surface Sampling Probe
Low-Temperature Plasma probe
Matrix-Assisted Laser Desorption Electrospray Ionization
Neutral Desorption Extractive Electrospray Ionization
Probe Electrospray Ionization
Radio-frequency Acoustic Desorption and Ionization
Rapid Evaporative Ionization Mass Spectrometry
Switched Ferroelectric Plasma Ionizer
Biannual Anal. Chem. Review-Harris/Fernández
Fernandez Group 2011
Surface Sampling
“Ambient” MS
Volatilization Principle
Liquid
Extraction
Ionization
Principle
ESI
DESI, DICE,
DEMI, LMJSSP, DEMI
Sonic spray
EASI
APPI
DAPPI
APCI
Chemical
Sputtering
Thermal
Mechanical
Laser Desorption/
Ablation
Acoustic
Neutral
Headspace
smapling
AP-TD/SI
PESI
ELDI, LAESI,
MALDESI
LIAD,
RADIO
ND-EESI
LD/APCI
LIAD
DAPPI
DAPCI,
DBDI
ASAP,
BADCI,
DART,
DCBI,
DEMI,
FAPA, LTP,
REIMS,
DEMI
Reviews by Cooks, Van Berkel, Eberlin, Fernández
Fernandez Group 2011
Outline
•Transmission Mode DART (TM-DART)
•Imaging DART
•DART-Ion Mobility
Fernandez Group 2011
Ambient MS in the Real World:
DART
Advantages include:
•No sample preparation required.
•Sample is not placed in vacuum.
•Sizeable objects can be directly examined in
the open air.
•Very high sample throughput.
•Can be coupled to any mass spectrometer
with an atmospheric pressure interface for
accurate mass or MS/MS experiments.
•No memory effects
Fernandez Group 2011
Direct Analysis in Real Time
(DART)
Glow Discharge
Grid Electrode Analyte Ions
He*
He*
He*
He or N2
1-5 L min-1
He*
He*
He*
He*
He*
3-5 kV Needle
H3O+
MH+
+
M
H3O
MH+
(analyte)
He*
He*
To TOF
MS
H2O
Heater
Heated metastables and Penning ionization
He* ( g ) + nH2O( g) → He( g ) + (H2O)n−1 H + ( g ) + OH− ( g )
Thermal desorption and declustering
Chemical sputtering and surface collisions
( m −1) H 2O
( H 2O) m H + ( g ) + AB( s ) 
→ AB( H 2O) m−1 H + ( g ) + H 2O( g ) −
→ ABH + ( g )
Direct Penning ionization and charge exchange reactions
He * ( g ) + AB ( g ) → He ( g ) + AB +. ( g ) + e −
AB( s ) →
 AB( g )
heat
(m−1) H2O
(H2O)m H + ( g) + AB( g) 
→AB(H2O)m−1 H + (g) + H2O( g) −
→ABH+ ( g)
Anal. Chem. 2005, 77, 2297
He* ( g ) + O2 ( g ) 
→ He( g ) + O2+. + He + e −
+.
O2 ( g ) + AB( g ) 
→ O2 + AB +.
Fernandez Group 2011
Protein
Precipitation,
TMS
Derivatization
DART
TOF MS
(+)
Raw
Data
Sets for
OC and
Controls
Internal Mass
Drift
Compensation
Export
as
ASCII
Serum samples were obtained from 44 women
diagnosed with serous papillary ovarian cancer
(stages I-IV) and 50 healthy women or women
with benign conditions (e.g., serous, simple, or
follicular cysts; Table 1) and run in triplicate.
Multivariate
Modeling
Functional Support
Vector Machine
Classification
(Linear, nonlinear)
Metabolomic
Discovery
Workflow
Feature Selection:
L1-norm SVM
RFE
Weston’s Method
Accurate mass and Isotope Pattern
Matching
Accuracy, Sensitivity, Selectivity
prediction
Elemental Formulae of
Discriminating Features
64-30 Test Set
validation (x50)
Leave-one-out
Cross-validation
Metabolite Database Searches:
HMDB
Spectral features
in Best Model
Putative Metabolite IDs
Fernandez Group 2011
DART Metabolomic Discovery
Workflow
Effect of helium gas temperature on DART-TOF MS sensitivity
for metabolomic profiling of derivatized serum: (a) background
corrected mass spectra at various helium temperatures, (b)
number of metabolites matched to HMDB database, and (c)
change in S/N of three mass spectrometric signals at m/z
205.12, 467.22, and 762.25 versus helium temperature.
Zhou et al., J. Am. Soc. Mass Spectrom., 2010, 21, 68-75
Fernandez Group 2011
DART Diagnostics Results
64:30 Split validation
Classifier type
fSVM
fSVM_NL
fSVM
fSVM_NL
fSVM
fSVM_NL
Feature selection
method
Number of
Features
1:7:20,000 subsampling
2,858
One-way ANOVA
(p=0.05)
3,017
One-way ANOVA
(p=0.01)
1,320
SENS(%)
SPEC(%)
ACC(%)
100.0
93.8
96.7
100.0
93.8
96.7
100.0
100.0
100.0
100.0
93.8
96.7
92.9
93.8
93.3
92.9
100.0
96.7
Fernandez Group 2011
Pathway Enrichment Analysis
• 153 elemental formulae were assigned to 299 unique endogenous
metabolites or xenobiotic compounds.
• These compounds mapped onto 25 pathways, suggesting differences
between cancer and noncancer groups in amine, amino acid, eicosanoid,
and TTP metabolisms.
• Differences in the
metabolisms of
carbohydrates and
estrogens have
lower confidence due
to ambiguity in
elemental formulas.
Fernandez Group 2011
More to DART Than Gas-Phase
Chemistry
TG
QG
VGrid
A
D3
Sample
G%
DART
GIST
θDART
VMS
VD
D1
Sample
MS
MS
D2
H1
H2
P1 P2
Fernandez Group 2011
DART with GIST interface
Fernandez Group 2011
TM-DART
Deltamethrin
MW: 505.21
Orifice
Sample
Holder
DART
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
Orifice
0.6
0.5
0.4
Sample
Holder
0.3
DART
0.2
0.1
0
Fernandez Group 2011
TM-DART
TP 039
Christina Jones
Manshui Zhou
Facundo Fernandez
Fernandez Group 2011
Outline
•Transmission Mode DART (TM-DART)
•Imaging DART
•DART-Ion Mobility
Fernandez Group 2011
Ionization Methods Used for Imaging
Advantages
Relative Weaknesses
Odd-shaped samples
In vivo
Native state (no matrix, no drying)
No surface damage
Soft as ESI
Can perform cationization etc. in
reactive mode
Limited Spatial
Resolution
Better Ion Transmission
Higher lateral
resolution than DESI
Limited ionization
efficiency
Unsurpassed for large
Biomolecules
Matrix interference in
Low Mw range
Matrix deposition
Highest lateral
resolution
Fragmentation
Fernandez Group 2011
IR-DART
Fernandez Group 2011
IR-DART
Fernandez Group 2011
Outline
•Transmission Mode DART (TM-DART)
•Imaging DART
•DART-Ion Mobility
Fernandez Group 2011
Portable IM Instrumentation
Reaction
region
Drift region
Detector
Gate
K=
3q  2π 


16Ω D N  µkT 
−1 / 2
Fernandez Group 2011
DART-IMS
i.
ii.
iii.
vii.
1.0
8/8
8/8
DMMP TPD:
DMMP
11.81 %
11.81%
7/8
7/8
Likelihood of Detection
0.8
iv.
v.
vi.
8/8
8/8
TM DARTIMS DMMP
0.28%
6/8
6/8
5/8
5/8
0.6
4/8
4/8
0.4
2/8
2/8
0.2
2/8
2/8
−
y=
0/8
0.0
0/8
0.1
1
+1
1 . 25
1 + (x / 1. 12 )
1
0/8
0/8
10
C oncentration (%, log10 scale)
Fernandez Group 2011
Multiplexed DART-IMS
SNR Gains vs. Conventional Mode
3.5
200 us Multiplexing
3.0
20 sweeps
100 sweeps
400 sweeps
2.5
2.0
1.5
1.0
n!
Combinations =
r!(n − r )!
r = 1, ~0.6%, 16 seqs
r = 2, 12.5%, 120 seqs
r = 4, 25%, 1820 seqs
r = 8, 50%, 12870 seqs
SNR Gains vs. Conventional Mode
5
400 us Multiplexing
4
20 sweeps
100 sweeps
400 sweeps
3
2
1
0
2%
5%
10%
30%
50%
Sequence Duty Cycle
Fernandez Group 2011