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Tandem Mass Spectrometry of Synthetic Polymers

Árpád Somogyi

Department of Chemistry and BiochemistryUniversity of Arizona

Summer Workshop

Problems with polymer analysis• Sample preparation

– Several polymers are not well soluble in conventional solvents

– Solventless technique– Cationizing with Na+, K+, and Ag+ by spiking– Synthesis of tailor (home) made matrices

• Degradation during ionization (especially with MALDI)– Photodissociation in MALDI (MALDI/ESI comparison

desirable)

• End group analysis reliable but better to have high resolution/accurate mass (FT-ICR)

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Molecular weight distribution defines polydispersit y of polymers

Polydispersity (PD) = Mw/Mn

Polystyrenewith Ag+

Zhu, H.; Yalcin, T.; Li, L. JASMS, 1998, 9, 275-281.

829.987

991.986

1143.205

1313.231

1433.246

1553.257

1723.288

1123.212

2013.333

2303.4052593.467

2933.604

* NB_89_M4\0_M16\1\1SRef, "Baseline subt."

0.0

0.5

1.0

1.5

2.0

5x10

Inte

ns.

[a.u

.]

1000 1500 2000 2500 3000 3500 4000 4500m/z

Trancated Vectra Polymer (Somogyi et. al., unpublished)

PD > 1.05

PD≈1.01

Zhu, H.; Yalcin, T.; Li, L. JASMS, 1998, 9, 275-281.

MS is an absolute method for MW determination(but remember possible degradation!)

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http://www.polymerprocessing.com/polymers/alpha.htm l

Poly(ethylene terephtalate) (PET)C10H8O4 (192.042259)

Polystyrene (PS)C8H8(192.042259)

Poly(methyl methacrylate) (PET)C5H8O2 (100.052430)

Poly(vinyl alcohol) (PVA)

C2H4O (44.026215)

- CH2-CH2-O-Poly(ethylene glycol) (PEG)

Repeating unit masses of polymers

0

1000

2000

3000

4000

Inte

ns.

[a.u

.]

500 1000 1500 2000 2500 3000 3500m/z

0

500

1000

1500

2000

Inte

ns.

[a.u

.]

1675 1700 1725 1750 1775 1800 1825 1850 1875m/z

Synthetic Polymer Analysis by MS (MALDI-TOF)

1684.205

1728.2311772.260

1816.2921660.310

4444

4444

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CH3OH exact mass: 32.0262 u

3 7 4 3 7 6 3 7 8 3 8 0 3 8 20

2 0

4 0

6 0

8 0

1 0 0

Re

lati

ve

In

ten

sit

y

m / z

3 5 7 0 3 5 7 2 3 5 7 4 3 5 7 6 3 5 7 80

2 0

4 0

6 0

8 0

1 0 0

Re

lati

ve

In

ten

sit

y

m / z

a

b

374.4183 (average mass)

374.2040 (exact mass)

3570.8741 (exact mass)

3572.9742 (average mass)

0 2 0 0 0 4 0 0 0 6 0 0 0 8 0 0 0

0

1

2

3

4

5

6

7

8

De

via

nc

efr

om

no

min

al

ma

ss

(da

lto

n)

m / z

c

[Ala 5+H]+

[Ala 50+H]+

exact mass

average mass

C15H28O6N5

C150H253O51N50

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854.2870

856.2832

857.2855

858.2872

859.2904 860.2930

861.2377

862.2416

3_OEB_000001.d: +MS

861.2365

862.2399

863.2428

864.2455

3_OEB_000001.d: C 45 H 42 Na 1 O 16 ,861.24

856.2811

857.2845

858.2873

859.2900

3_OEB_000001.d: C 45 H 46 N 1 O 16 ,856.28

0

1

2

3

7x10Intens.

0.00

0.25

0.50

0.75

1.00

1.25

7x10

0

1

2

3

4

7x10

854 856 858 860 862 864 m/z

FT-ICR - Accurate Mass Measurements(ESI Ionization, MeOH:ACN 1:1)

C45H42O16Na+

C45H42O16NH4+

FT-ICR - Accurate Mass Measurements

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MS/MS spectra of polymers depend on

• The cationizing agent (sample preparation)

• Instrument type, ion activation method

– Low energy (eV) collisions (Q-TOF, FT-ICR (SORI, IRMPD)

– High energy (keV) collisions (TOF-TOF)

MS/MS studies of synthetic polymers date back to ea rly 90s (Jackson, A. T.; Yates, H. T.; Bowers, M. T.; Lattimer, R. P.; Wesdemiotis, C., etc.)

Renaissance, due to sophisticated instrumentation

Main goal is to determine polymer structure but bas ic studies such as comparison of different activation methods are emerging

Survival yield curveM/(M+ΣF)

SY50: characteristic;easy spectra evaluation

low energy spectrum, little fragmentation

correct MW distribution

high energy spectrum, lot of fragments

good “fingerprint”

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Results for PEGsMemboeuf, IMMS 2009 (Retz)

Anal. Chem. 82 2294 (2010)

very good linear relationship

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96.8853

165.0539

237.5432

329.1004

381.2949

493.1461

537.4941613.1692

657.1901

777.2073

3_OEB_812_QCID_12eV_000002.d: +MS2(812.0)

0

2

4

6

6x10Intens.

100 200 300 400 500 600 700 800 900 m/z

111.9153.6

280.7 329.1

457.1

489.1 612.4

817.2

3_OEB_817_QCID_12eV_000001.d: +MS2(817.0)

0.00

0.25

0.50

0.75

1.00

1.25

1.50

7x10

100 200 300 400 500 600 700 800 900 m/z

96.9

165.1

263.4

329.1

357.2

457.1

493.1

657.2

817.2

3_OEB_817_QCID_30eV_000001.d: +MS2(817.0)

0

2

4

6

6x10

100 200 300 400 500 600 700 800 900 m/z

812

12 eV

817

12 eV

817

30 eV

Na+

Na+

NH4+

O

O CH2 CH2 *m

nO

3-OEB polymerESI, MeOH:ACN 1:1

Q-CID MS/MS spectra of ammoniated (NH4+) and sodiated (Na+) ions of 3-OEB polymers in

a FT-ICR instrument (ApexQh)

Somogyi et al., unpublished

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817.308

328.705 492.776186.682 657.011120.738 284.652 354.682 544.397443.72066.510 240.848

0

1

2

3

4

5

4x10

Inte

ns. [

a.u

.]

100 200 300 400 500 600 700 800 900m/z

100 200 300 400 500 600 700 800 900 m/z100 200 300 400 500 600 700 800 900 m/z

96.9

165.1

263.4

329.1

357.2

457.1

493.1

657.2

817.2

0

2

4

6

100 200 300 400 500 600 700 800 900 m/z

QCID30 eV

MALDITOF-TOF(keV)

328.705

492.776

186.682

657.011

120.738514.780

284.652146.719

672.727

679.028310.689 456.55290.823 354.682 544.397208.735 400.629248.685

0

1000

2000

3000

4000

100 200 300 400 500 600 700m/z

Some Examples for Tailor-Made Matrices

NN

FF

F F

HOCOOH

M-1

NN

FF

F F

FF

FF

F FM-3

FF

F F

HOCOOCH3

M-2

NN

FF

F F

HOOH

FF

F FM-4

FF

F F

HOOH

FF

F F

M-5

FF

F F

FF

FF

F F

M-6

FF

F F

FCOOCH3

M-7

NN

FF

F F

H3COOCH3

FF

F FM-9

NN

FF

F F

HOCOOCH3

M-8

Somogyi, et al., Macromolecules, 2007, 40, 5311-5321.

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Practical importances of phenanthrolinePractical importances of phenanthroline--functional ized PEGsfunctionalized PEGs

� stabilization of magnetic nanoparticles(e.g. Fe3O4)

�hydrofilic networks by complex formation

KékiKéki, , S.; S.; KukiKuki, , ÁÁ.. KukiKuki;; Nagy, Nagy, M.; M.; Nagy, L.; Nagy, L.; ZsugaZsuga, M., M.JASMSJASMS, 2010, , 2010, 2121, 1561, 1561--1564.1564.

Change of Change of the the absorbance at 515 nm absorbance at 515 nm versus versus molar ratio of the added molar ratio of the added Fe(II)Fe(II)--ions and phenanthroline functions of ions and phenanthroline functions of PEGsPEGs

0

0.2

0.4

0.6

0.8

1

1.2

350 450 550 650

λλλλ (nm)

Abs

orba

nce

CT transition

0.0

0.2

0.4

0.6

0.8

1.0

1.2

0 0.2 0.4 0.6 0.8 1

[Fe2+]/[phen]

Abs

orba

nce

(515

nm

)

▲εεεε≈10300 M-1cm-1♦εεεε≈11090 M-1cm-1

Fe2+ : PEG_phen = 1: 3

Fe2+ : phen_PEG_phen = 2: 3

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Synthesis of phenanthrolineSynthesis of phenanthroline--functionalized PEGsfunctionalized PEGs

N N

HO

N N N N

HOO

cc. H2SO4, reflux, 1 h

50% NaOH, pH=7

reflux, 72 h

SOCl2, abs. tolueneCH3 O CH2 CH2 OH

n

Cl

n

CH3 O CH2 CH2

N

N

OCH3 O CH2 CH2

nn

CH3 O CH2 CH2 Cl NaH, abs. DMF

reflux, 48 h+

N N

HO

NaH, abs. DMF

reflux, 48 h+

n-1

CH2 O CH2 CH2 ClCH2Cl

nN

N N

NCH2 CH2 OO

2

(PEG_phen)

(phen_PEG_phen)

(Mn = 1100 g/mol)

(Mn = 1500 g/mol)

ESIESI--MS spectrum of Fe(PEG_phen)MS spectrum of Fe(PEG_phen) 332+2+

0.0

0.5

1.0

1.5

2.0

2.5

4x10Intensity

600 800 1000 1200 1400 1600 1800 2000 2200 2400 m/z

FeLFeL332+2+

[FeL[FeL 33+NH+NH44]]3+3+

[FeL[FeL 33+2NH+2NH44]]4+4+

[FeL[FeL 33+2NH+2NH44+Na]+Na]5+5+

[FeL[FeL 33+3NH+3NH44+Na]+Na]6+6+

L = PEG_phenL = PEG_phen

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ESIESI--MS intensity distribution of PEG_phen and Fe(P EG_phen)MS intensity distribution of PEG_phen and Fe(PEG_ph en)332+2+

+Fe(II)+Fe(II)

Fe2+ + L i + L j + Lk FeL i+j+k2+ (n=i+j+k)

Theoretical model:Theoretical model:

0

0.02

0.04

0.06

0.08

0.1

0.12

15 20 25 30 35 40

number of EO units

Pro

babi

lity

0.0

0.2

0.4

0.6

0.8

1.0

60 80 100 120

number of EO unitsN

orm

aliz

ed in

tens

ity

measured

simulated

kj

kjiin PPPP ∑

∞

==

1,,

ESIESI--MS/MS of Fe(PEG_phen)MS/MS of Fe(PEG_phen) 332+2+

727.

35

1493

.31

2193

.30

0

100

200

300

Intensity

200 400 600 800 1000 1200 1400 1600 1800 2000 m/z

Fe(PEG_phen) 32+ Fe(PEG_phen) 2

2+ + PEG_phen

Fe(PEG_phen) 22+ Fe(PEG_phen) 2+ + PEG_phen

0

0.2

0.4

0.6

0.8

1

10 30 50 70

number of EO units

norm

alze

d in

tens

ity

80 V

90 V

simulated

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Very recent polymer MS and MS/MS articles in JASMS (April, 2011)

Szyszka, R.; Hanton, S. D.; Henning, D.; Owends, K. G. “Development of a CombinedStandard Additions/Internal Standards Method to Qua ntify Residual PEG in Ethoxylated

Surfactants by MALDI TOFMS” JASMS, 2011, 22, 633-640.

Song, J.; Siskova, A.; Simons, M. G.; Kowalski, W. J.; Kowalczuk, M. M.; van den BrinkO. F. “LC-Multistage Mass Spectrometry for the Char acterization of Poly(Butylene

Adipate-co-Butylene Terephtalate) Copolyester” JASMS, 2011, 22, 641-648.

Fouquet, T.; Humbel, S.; Charles, L. “Tandem Mass S pectrometry of Trimethylsilyl-TerminatedPoly(Dimethylsiloxane) Ammonium Adducts Generated b y Electrospray Ionization”

JASMS, 2011, 22, 649-658.