advanced polymer characterisation using hdms
TRANSCRIPT
©2015 Waters Corporation 1
Advanced Polymer Characterisation using High Definition Mass Spectrometry
Oliver Burt
©2015 Waters Corporation 2
High Definition Mass Spectrometry …..a new dimension of discovery
What is HDMS? – The combination of high resolution tandem mass spectrometry and
high efficiency ion mobility based measurements and separations. – High Definition Mass Spectrometry
What are the benefits of HDMS? 1. Increase Selectivity, Specificity and Confidence
Remove interferences, improve detection limits, separate mixtures, increase peak capacity
2. Structural analysis Separate isomers and conformers, measure shape (cross-
section), or enhance fragmentation studies
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What is Ion Mobility?
Separation of ionic species as they drift through a gas under the influence of an electric field
Rate of drift is dependent on ion’s mobility through the gas
Mobility (K) is dependent on factors such as:- – Mass – Charge – Interaction cross section (shape)
Ability to separate isobaric species if they have different
interaction cross sections
Vd = ion velocity E = electric field gradient
Vd = K . E
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Ion Mobility Spectrometry (IMS) …Drift tube IMS
An ion in a compact form has a high mobility, hence shorter drift time
The same ion in a more open conformation has a lower mobility, hence a longer drift time
Gat
e
Det
ecto
r
Neutral Buffer Gas (-ve force)
Ring Electrodes (Potential Gradient. +ve force)
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Real Life Example
Two paper ‘isomers’ have: – same mass – same ‘charge’ – different shapes
Gravitational force takes place of Potential Gradient of ring electrodes
Air resistance takes place of gas in drift tube What is the result?
– ‘Ball’ has higher mobility and falls faster – Sheet has lower mobility and falls slower
Paper Sheet Paper ‘Ball’
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Ion Mobility Applications
IMS and Mass Spectrometry have been combined before Previous hybrids
– Low duty cycle & Low sensitivity – Consequence of “gating” process
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What is it? – Platform combining high efficiency ion mobility with
Qtof tandem mass spectrometry
What does it do? – Enables analysis of compounds differentiated by size and
shape, as well as mass o Increased specificity and sample definition
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Click here for product info
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TOF mode HDMSTM mode
SYNAPT G2-Si Operating Modes
• Step-up from Xevo G2-S Qtof
• QuanTof enabled
− Exact Mass <1ppm, 50k Resolution FWHM
− Linearity and Scan Speed
• MS/MS capability
• Universal source architecture
• MALDI source
• Data Processing Tools
Ion Mobility Separations
• Increase peak capacity of separations
• Probe structural conformation
• Physical measurement of ions in gas phase
• Enhance information from MS/MS
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SYNAPT G2-Si Schematic
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Travelling Wave Ion Mobility Separation
Turbomolecular Pumps
Trap IMS Transfer
Gate
N2
Ar
Ions In
Ions Out
0.05mbar
He
0.05mbar 3mbar
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Travelling Wave Ion Mobility Separation with MS
Precursor ions separated by IMS
Drift time
m/z
Drift time
m/z
Precursor and products share same drift time
From Source via Quadrupole
To Tof/MS Analyzer
©2015 Waters Corporation 13 Drift Time
m/z
Travelling Wave Ion Mobility Separation with MS
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SYNAPT ‘Heat Map’
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SYNAPT ‘Heat Map’ M
ass
(m/z
)
Drift Time
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SYNAPT ‘Heat Map’
IMS : 0.9 mb N 2 Pulse : 10 V
Velocity : 300 m/s
4+
3+
1+
2+
2+
6+
Mas
s (m
/z)
Drift Time
Orthogonal separation reveals structure within complex sample
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SYNAPT ‘Heat Map’
IMS : 0.9 mb N 2 Pulse : 10 V
Velocity : 300 m/s
4+
3+
1+
2+
2+
6+
Mas
s (m
/z)
Drift Time
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Resolving Structural Isomers
Drift time
Precursor ions separated by IMS
TIC
Drift time
m/z
Precursor and products share same drift time
NB. Data from SYNAPT G1
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Polymer Backbone Evaluation
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TOF mode
SYNAPT G2-S Operating Modes
• Step-up from Xevo G2-S Qtof
• QuanTof enabled
− Exact Mass <1ppm, 40k Resolution
− Linearity and Scan Speed
• MS/MS capability
• Universal source architecture
• MALDI source
• Data Processing Tools
©2015 Waters Corporation 21
Structural Confirmation of Polymeric Material using MS/MS and Fragmentation
Mechanisms
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Background
The backbone connectivity of a polymer is important because it has an impact on its physical properties – MS/MS experiments can provide the data to confirm a polymer’s
backbone connectivity
Polylactides have recently attracted a lot of attention from both academic and industrial research due to their bio-compatible and bio-degradable nature
This polymer was synthesized via a ring opening polymerization reaction
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MS Results
The first step to determining the polymer’s backbone connectivity is to perform an MS experiment, followed by MS/MS analysis
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Data Interpretation
The MS/MS results show three series of ions
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Fragmentation Mechanisms (1)
The MS/MS data are consistent with the following three fragmentation mechanisms
OCH3
O
O
O
CH3
O
O
CH3
O
O
CH3
OH
Hn
nCH2
OCH3
O
OH
O
O
O
CH3
O
O
CH3
OH
H
n
OH
O
CH2
OH
O
CH3
O
O
CH3
OH
86 mass unit loss
72 mass unit loss
Series
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Fragmentation Mechanisms (2)
CH3
OCH3
O
O
O
CH3
O
O
CH3
O
O
O
O
CH3
OH
H
n
nCH3
OCH3
O
O
O
CH3
O
O
O
O
CH2
H
OH
O
CH3
OH
nCH3
OCH3
O
O
O
CH3
O
O
CH2
OH
O
CH2
90 mass unit loss
72 mass unit losses
Series
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Fragmentation Mechanisms (3)
OCH3
O
O
O
CH3
O
O
CH3
O
O
CH3
O
O
O
O
CH3
OH
H Hn
CH2
OCH3
O
OH
O
CH3
O
O
CH3
O
O
CH3
O
O
CH2
OH
O
CH3
OH
n
176 mass unit loss
Series
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Polymer Folding Patterns
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HDMSTM mode
SYNAPT G2-S Operating Modes
Ion Mobility Separations
• Increase peak capacity of separations
• Probe structural conformation
• Physical measurement of ions in gas phase
• Enhance information from MS/MS
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Polymer Folding Patterns
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Polymer Folding Patterns
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Polymer Folding Patterns
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Linear vs Branched
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Linear PEG Mobility Plot
Drift time is governed by: – Size – Shape – Charge state
3D size and shape of a
polymeric ions are governed by: – Repeat unit chemistry – 3D arrangement – Backbone connectivity – Cation(s)
SG2-S_20130213_001.raw : 1
Increasing no. monomer units
Incr
easi
ng C
CS
A mobility plot combines exact mass measurements, ion intensity and 3D size resulting in distinctive mobility plots that could be considered as a “fingerprint”.
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Repeat Experiments
SG2-S_20130213_001.raw : 1
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Uncharacterised PEG
SG2-S_20130213_001.raw : 1
Singly charged
Doubly charged
Characterized Uncharacterized
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MS/MS Results
MS/MS Spectrum Characterized PEG
MS/MS Spectrum Uncharacterized PEG
863
877
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Data Interpretation
MS/MS Spectrum Characterized PEG
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Fragmentation Mechanism
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Mobility Plot – Uncharacterized PEG
Some data is be more easily viewed in a mobility plot
DriftScope allows data to be selected and viewed in isolation from the full data set.
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Uncharacterized PEG
Several series of ions with a mass difference of 44 Da – Labeled with white and red
lines
At 608 m/z a third series of ions becomes visible – Highlighted with the green
arrow
608 m/z is consistent with the loss of three end groups – Indicating the unknown
sample is branched
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Resolving Different Polymer Charge States
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20120710_SG2_004.raw : 1
Resolve Charge States
PMMA 4000 PEG 3400
m/z
Drift
tim
e
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Resolve Charge States
20120710_SG2_004.raw : 1
3+
2+ 2+
3+
1+
5+ 4+
Drift
tim
e
m/z
PMMA 4000 PEG 3400
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Resolve Charge States
PMMA 2+ PEG 3+
http://www.waters.com/webassets/cms/library/docs/720004342en.pdf
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Simplifying Complex Polymer Data Sets
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99 Da Repeat Unit
44 Da Repeat Unit
O
NCH3 CH3
CH3
CH2
O
CH3
x y
n
PDMA-co-PEGMA
Simplify Complex Data Sets by Reducing Spectral Complexity
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Log scale
Simplify Complex Data Sets by Reducing Spectral Complexity
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Square root scale
Simplify Complex Data Sets by Reducing Spectral Complexity
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Simplify Complex Data Sets by Reducing Spectral Complexity
Removing “hot spots”
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Simplify Complex Data Sets by Reducing Spectral Complexity
1° series 99 mass difference
PDMA polymer
2° series?
99 99 99
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Zoom in on primary series
Select sub-series
Simplify Complex Data Sets by Reducing Spectral Complexity
2° series 44 mass difference
PEG component @ 1%
44 44 44
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Increased Peak Capacity for Separation – Resolve structural isomers – Resolve nominal isobaric
interferences – Resolve charge states in complex
spectra – Resolve ions with different charge
sites on same molecule – Enable simple identification of
relationships between components – Family classes
– Extends capabilities of UPLC Tof/MS o Resolve compounds that
chromatography may not o Resolve isomers that mass
resolution cannot
Physical Measurement of ions in gas phase – Determine CCS of ions – Confirm identity of structural
isomers – Observe polymer conformation
Advanced Structural Elucidation – Utilise HDMSE capability
o Combines mobility separations and MSE acquisition
– Enhanced MS/MS capability o Select precursors in quad;
fragment in trap and transfer region
o Provides MS3 capability
HDMS Capabilities for Chemical Materials Characterisation
©2015 Waters Corporation 54
Click here for SYNAPT G2-Si – Product Information
Click here for Poster – HDMS Compare for complex polymeric materials
Click here – Polymer Analysis Application Handbook
Click here – ACQUITY Advanced Polymer Chromatography system
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