Interfacing Mass Spectrometry with Separation Methods for Synthetic Pol mer Anal sis Polymer ...

42 Pages·2015·1.58 MB·English

Interfacing Mass Spectrometry with
Separation Methods for Synthetic
PPoollymmeerr AAnnaallyssiiss
Chrys Wesdemiotis
The University of Akron, Departments of Chemistry
andd PPollymer SSciience, AAkkron, OOHH 4444332255
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Mass spectrometry (MS): separation + characterization
based on mass ((m/z)) measurement
analytes
ssoofftt
ionization Key step
ggaass-pphhaassee
molecular
MS
Separation based on mass (m/z) of
ions
molecular ions.
Composition + structure information
fragmentation
based on the m/z values of molecular and
fragment ions in MS and MS/MS spectra
ffrraaggmmeenntt
MMSS//MMSS
ions
New ionization methods (MALDI, ESI, APCI, DESI) have enabled
the MS analysis of a wide range of synthetic polymers and are now
widely used for their molecular structure characterization.
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CChhallllenges iin mass-bbasedd anallysiis
PPoollyymmeerriizzaattiioonnss oofftteenn ccrreeaattee ccoommpplleexx mmiixxttuurreess tthhaatt aarree
impossible to characterize by simple (1-D) MS due to
discrimination effects (in ionization or detection).
IIssoobbaarriicc ccoommppoonneennttss aanndd iissoommeerriicc aarrcchhiitteeccttuurreess ccaannnnoott uussuuaallllyy
be distinguished by m/z measurement alone.
With ESI, overlapping charge distributions complicate
mmaassss ddeetteerrmmiinnaattiioonn aanndd, hheennccee, ccoommppoossiittiioonn aassssiiggnnmmeennttss.
Such problems can be addressed by interfacing MS with a
separation method either before ionization (LC-MS) or after
ionization (IM-MS: ion mobility mass spectrometry, IM-MS).
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CChhrroommaattooggrraapphhiicc sseeppaarraattiioonn
4
Online LC-MS of polymers
The most widely used HPLC method for
synthetic polymers is gel permeation
chromatography (GPC), which separates
aaccccoorrddiinngg ttoo hhyyddrrooddyynnaammiicc vvoolluummee ((ssiizzee))..
Interactive, reverse-phase LC, which separates
based on chemical composition, functionality,
aanndd mmaassss,, iiss lleessss ccoommmmoonn iinn ppoollyymmeerr aannaallyyssiiss,,
but ideally suitable for the separation of mixtures
with constituents of different polarities, as found
in amphiphilic polymers; it is also suitable for
oonnlliinnee LLCC-EESSII-MMSS..
VV. SSciionttii, BB.CC. KKattzenmeyer, NN. SSollakk EErddem, XX. LLii, CC. WWesddemiiottiis, EEur. JJ. MMass SSpecttrom. 1188 ((22001122)) 111133.
N. Solak Erdem, N. Alawani, C. Wesdemiotis, Anal. Chim. Acta 808 (2014) 83-93.
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PEO-glucam sesquistearate (nonionic surfactant)
RR = ((sstteeaarraattee)) oorr HH
n ≈ 5; ~1.5 mol stearate per mol surfactant
avg
GGeenneerraallllyy aa mmiixxttuurree ooff::
PEO-glucam mono and multiple stearates PEO + stearates
Glucam core (C H O ) = isobaric with 4 x C H O (EO monomer).
7 12 5 2 4
N. Solak Erdem, N. Alawani, C. Wesdemiotis, Anal. Chim. Acta 808 (2014) 83-93.
B.C. Katzenmeyer, S. Hague, C. Wesdemiotis, Anal. Chem., submitted. 6
PEO-glucam sesquistearate (nonionic surfactant)
1
PEO-glucam
2
monostearate
6.48 PEO-glucam
RP-UPLC
distearate
7.83
PPEEOO--gglluuccaamm
tristearate
PEO PEO
monostearate distearate
66.6666
PEO
PEO
9.66
aggregates
0.41 2.74
0.00 2.75 5.50 8.25 Time [min] 11.00
hydrophobicity
Solvent A: 2.55 mM NH OAc in 97% H O / 3% MeOH – Solvent B: MeOH – Flow rate 0.4 mL/min
44 22
A / B : 100:0 → 60:40 (0-2 min); 60:40 → 40:60 (2-3 min); 40:60 → 0:100 (3-7 min); 100% MeOH (>7 min)
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LC-MS & LC-MS2 analysis of peak 1
11
754.498
2+
  
LC-MS 

Accurate m/z: [M + 2NH ]2+ of
 4

((PEO)) -gglucam monostearate
66.4488 mmiinn nn

 with n = 26
 
3+
  1+
       ✚✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ 4✚4 D✚✚a ✚✚ ✚✚ ✚✚
300 675 1050 1425 m/z
LC-MS2
PPEEOO-gglluuccaamm
664455.3399
monostearate
2 [M + 2Li]2+
2 3. 787.544
5. 3 (n = 28)
4 3
2
-284
44
11 sstteeaarriicc
Da
acid loss
*311.3
1284.82 1568.09
100 600 1100 1600 m/z
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LC-MS & LC-MS2 analysis of an oligomer in peak 2
2 x 284 Da
LLCC--MMSS2 stearic acid CH CH O H
22 22
n
loss O PEO-glucam
7.83 min distearate
O OCH
3
0
2
2
4
2 3.33 .6. HH OOCCHH2CCHH2 OO OO CCHH2CCHH2OO sstteeaarraattee
5. 3 5 n n
4 7 O
2 -284 CH CH O stearate
-284 2 2
44 n
*311.3
Da
[[MM ++ 22LLii]]2+
661144.229911
898.549
(n = 29)
222.55312 506.86715 790.1161
200 400 600 800 1000 1200 1400 1600 1800 m/z
CCoommpplleettee mmiixxttuurree sseeppaarraattiioonn && cchhaarraacctteerriizzaattiioonn bbaasseedd oonn ppoollaarriittyy.
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PEGylated Substance P
++ ++
substance P PEGylated substance P
Methoxy &
(peptide-polymer
succinimide
conjugate)
functionalized
PEG
Potential PEGylation sites
R-P-K-P-Q-Q-F-F-G-L-M
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