solvent-free sample preparation for api and maldi … wctow2013 ling.pdf · solvent-free sample...

Solvent-Free Sample Preparation for API and MALDI Mass Spectrometry

Yun Ling

Department of ChemistryUniversity of British Columbia, Vancouver, Canada

Why Solvent-Free Sample Preparation?

Solubility Issues• Insoluble (Synthetic polymers)• Only soluble in less volatile solvents

(Organometallic or coordination compounds in DMSO)

Stability Issues• Reacting (Organometallic and Organic

Compounds)• Dissociation (Coordination Compounds)

Atmospheric Solids Analysis Probe (ASAP) Mass Spectrometry

EI MS- Direct Insertion Probe (DIP)• Sample placed on the probe tip• Transferred into the high vacuum of

the EI ion source API (ESI/APCI)-MS Sample

Preparation• Choose solvent and make sample

solution• Introduce sample solution to the API

ion source by infusion or HPLC pump ASAP MS - Atmospheric-Pressure

Solids Analysis Probe• Sample placed on the probe tip• Introduced into the API ion source

DESI - Desorption Electrospray Ionization

ASAP – Atmospheric Solids Analysis Probe

Ambient Ionization Mass Spectrometry

• Direct analysis-Native state

• No or little sample preparation

ASAP Probe

Operations of ASAP ESI or APCI ion source-

Corona discharge voltage

Positioning of the probe tip

Temperature of the desolvation gas

Flow rate of the desolvation gas

Cleanliness of the probe

m/z340 360 380 400 420 440 460 480 500

%

0

100 376.1

358.1

360.1

378.1 HaloperidolC21H23NO2FClExact Mass:375.1

m/z580 590 600 610 620 630 640 650 660 670 680 690 700

%

0

100 609.3

610.3 ReserpineC33H40N2O9Exact Mass:608.3

[M+H]+

[M+H]+

Mass Spectra of Polar Organic Compounds by ASAP

m/z260 270 280 290 300 310 320 330 340 350 360 370 380 390

%

0

100 299.3

298.3271.3300.3

Methyl StearateC19H38O2Exact Mass: 298.3

[M+H]+

M+.

m/z180 190 200 210 220 230 240 250 260 270

%

0

100 183.1

182.1

181.1184.1

m/z260 270 280 290 300 310 320 330 340 350

%

0

100 287.3

286.3

269.3

285.3 288.3 303.3

BenzophenoneC12H10OExact Mass: 182.1

5-androstene-3,17-dioneC19H26O2Exact Mass: 286.2

[M+H]+

[M+H]+

M+.

M+.

O

O

H

H

H

Mass Spectra of Non-Polar Organic Compounds by ASAP

m/z400 450 500 550 600 650 700 750 800 850 900 950

%

0

100

%

0

100 691

690

689688

685

429

693

694

941

691

429

428

427

426

423

479

447

464

556

480

690

688557

685

693

726725 728

729

Mass Spectra of Chlorocyclopentadienylbis(triphenylphosphine)ruthenium(II)

ESI-MS with DCM/MeOHas Solvents

ASAP-MS with solid

[M-Cl]+

[M-Cl]+

M+.

[M-Cl-P(Ph)3]+

m/z685 690 695 700 705 710 715 720 725 730 735 740 745

%

0

100

%

0

100 691

690

689688

685

693

694

691

690

688

685

693

726725694

723

728729

m/z716 718 720 722 724 726 728 730 732 734 736 738 740

%

0

100

%

0

100 726

725

724723

720

728

727

729730

726

725

724723

720

728

727

729730

C41H35P2ClRuNominal Mass: 726

[M-Cl]+

[M-Cl]+

M+.

ESI-MS

ASAP-MS

Theoretical

ASAP-MS

Mass Spectra of Ru-Complex by ASAP and ESI

Mass Spectra of Poly(ethylene glycol) and Poly(propylene glycol) by ASAP

m/z200 400 600 800 1000 1200 1400 1600 1800

%

0

100 177

221

265 309

353

397 441485 10761032

573 944617661

900 1120

m/z1200 1400 1600 1800 2000 2200 2400 2600 2800

%

0

100 2074

1900

1899

1784

1725

1666

1608

15511493

1434

1958

2016

2132

2133

2190

2191

2249

2306

2365

24232424 2538

PEG1000Repeat Mass: 44Da

PPG2000Repeat Mass: 58Da

Mass Spectra of Mineral Oil by ASAP- Direct Analysis

m/z200 300 400 500 600 700 800 900 1000

%

0

100

%

0

100

%

0

100 295281

259245

183169

197

309

323

337371

337323309

211 225

351

365

379

367311255

199183169 239 295 351

423

409

479

465521

535

577591

Desolvation Temperature: 300C



Repeat: 14Da

Repeat: 14Da

Repeat: 56Da

m/z180 190 200 210 220 230 240 250 260 270 280

%

0

100 195.1

194.1196.1

m/z160 180 200 220 240 260 280 300

%

0

100 152.1

153.1303.2

CaffeineC8H10N4O2Exact Mass: 194.1

AcetaminophenC8H9NO2Exact Mass: 151.1

Instant Coffee

Tylenol Tablet

OH NH

CH3

O

N

N

O

O N

NCH3CH3

CH3

[M+H]+

[M+H]+

M+.

M+.

Direct Analysis of Instant Coffee and Tylenol Tablet by ASAP

Ion Formation of ASAP Mass Spectrometry

Radical Ions or Protonated Molecules?• Charge Transfer -

Radical Ions• Proton Transfer -

Protonated Molecules• Mixed Mode

Modulation of Ion Formation?

DESI - Desorption Electrospray Ionization ASAP

DICE -Desorption

Ionization by Charge

Exchange

ASAP Probe

Mass Spectra of Anthracene and Pyrene by ASAP with Different Solvents

AnthraceneC14H10Nominal Mass:178

PyreneC16H10Nominal Mass:202

No solvent

water

methanol

toluene

benzene benzene

toluene

methanol

water

No solvent

m/z176 178 180 182 184 186 188 190

%

0

100

%

0

100

%

0

100

%

0

100

%

0

100 179

178180

179

178 180

179178

180

178 179

180

178

179180

m/z202 204 206 208 210 212 214 216 218 220

%

0

100

%0

100

%

0

100

%

0

100

%

0

100 203

202 204

203

204

203

204

202 203

204

202 203

204

[M+H]+

[M+H]+

[M+H]+

[M+H]+

[M+H]+

[M+H]+

[M+H]+

[M+H]+

[M+H]+

[M+H]+

M+.

M+.

M+.M+.

M+.

M+.

OH3CN O

CF3

CH3

Coumarin 152C12H10F3NO2Nominal Mass:257

No solvent

Water

Methanol

Toluene

Benzene

Mass Spectra of Coumarin 152 by ASAP with Different Solvents

m/z260 270 280 290 300 310 320 330 340

%

0

100

%

0

100

%

0

100

%

0

100

%

0

100 258

257

258

258

257 258288 303

257258

[M+H]+

[M+H]+

[M+H]+

[M+H]+

[M+H]+

M+.

M+.

M+.

Mass Spectra of Cholesterol by ASAP with Different Solvents

CholesterolC27H46ONominal Mass:386

No solvent

Water

Methanol

Benzene

Toluene

HOH

H

H

m/z360 370 380 390 400 410 420 430 440 450

%

0

100

%

0

100

%

0

100

%

0

100

%

0

100 369370

369

385370

369370

369368

386

385370

387 401

386369368383382 400387

401

M+.

M+.

[M-H2O+H]+

Thermochemical Data –Charge Exchange or Proton Transfer?

Compound MW (Da) IE (eV) PA (kJ/mol)Nitrogen 28 15.58 494Water 18 12.62 691Methanol 32 10.84 754Toluene 92 8.83 784Benzene 78 9.2 750Anthracene 178 7.44 877Pyrene 202 7.42 869Benzophenone 182 9.08 882Cholesterol 386

Summary- ASAP

Provides a useful tool for rapid and direct analysis for wide range of samples using API MS.

Opens up the analyses of compounds with solubility issues.

Avoids solvent to remove other complications such as unwanted side reactions, ion suppression.

Solvent-Free MALDI Sample Preparation

MALDI Sample Preparation - intimate contact between the analyte and the matrix

Solvent-Based MALDI Sample Preparation• Preparation of solutions of sample, matrix, and

cationization agent (if needed)• Mixing of the solutions • Loading of solution mixture to the MALDI target• Drying

Solvent-Free MALDI Sample Preparation• Mixing of sample and matrix (solids mixing)• Application of the solid mixture to the MALDI target

Comparison of SF- and SB-MALDI : Practical Considerations

S-F MALDI S-B MALDIChoice of

MatrixStructure of

analyteStructure of analyte

Choice of Salt (if needed)

Structure of analyte

Structure of analyte

Choice of the Solvent

NA Analyte, matrix, and salt (if needed)

Matrix-to-Analyte Ratio

10-100:1 100-1000:1

Salt-to-AnalyteRatio

1-10:1 1-10:1

Solvent-Free Sample Preparation-The Vortex Method

1. Add analyte and matrix, as well as cationization agent (if needed) to a small plastic, snap-lid vial.

2. Add two 1 mm S/S balls. 3. Vortex at high speed on a

standard lab vortex mixer for less than 1 minute.

4. Remove small amounts of material with a metal spatula.

5. Apply the solid mixture to the target to form a thin film.

3000 3500 4000 4500 5000 5500 6000 6500 m/z

PEG5K

S-B

S-F

MALDI Mass Spectra of Poly(ethylene glycol) using DHB as matrix.

Repeat: 44Da

8000 9000 10000 11000 12000 13000 m/z

PEG11K Repeat: 44Da

S-B

S-F

3000 3500 4000 4500 5000 5500 6000 6500 m/z 5000 6000 7000 8000 9000 m/z

PS5KPS8K

S-BS-B

S-FS-F

MALDI Mass Spectra of Polystyrene using Dithranol as matrix and AgTFA as cationization agent

Repeat: 104Da

995.3

1011.3

1157.4

1173.4

1319.5

1335.5

1000 1050 1100 1150 1200 1250 1300 1350m/z

-Cyclodextran (CD)C36H60O30Exact Mass: 972.3

-Cycledextran (CD)C42H70O35Exact Mass: 1134.4

-Cyclodextran (CD)C48H80O40Exact Mass: 1296.4

S-F MALDI with DHB as matrix

MALDI Mass Spectra of Cyclodextrans

[M+Na]+

[M+Na]+

[M+Na]+

Solid State Packing of Pt4 Macrocycle - different views

ON

O

N

Pt

O

NO

N

Pt

ON

O

N

Pt

O

NO

N

Pt

R'R'

R'R'

R

R

R

R

Molecular Structure of Pt4 Macrocycle

3945 (1)

7904 (2)

11859 (3)

15807 (4)19755 23702 27642 31592 35519 39462

5000 10000 15000 20000 25000 30000 35000 40000m/z

19755 (5)

23702 (6)

27642 (7)31592 (8) 35519 (9) 39462 (10)

20000 22500 25000 27500 30000 32500 35000 37500 40000 42500 m/z

C196H260N12O24Pt4

Average Mass: 3948

S-F MALDI with DCTB as matrix

MALDI Mass Spectra of Pt4 Complex

2768 (1)

5551 (2)

8330 (3)

11111 (4)

13898 (5)

16679 (6)19458 (7) 22232 25002 27783 30552 33329 36095

5000 10000 15000 20000 25000 30000 35000m/z

16679 (6)

19458 (7)

22232 (8)

25002 (9)27783 (10) 30552 (10) 33329 (11) 36095 (12)

17500 20000 22500 25000 27500 30000 32500 35000 37500 m/z

C112H92N12O24Pt4

Average Mass: 2770

S-F MALDI with DCTB as matrix

2444 (1)

4851 (2)

7257 (3)

9664 (3)12070 (4) 13219 14472

2000 4000 6000 8000 10000 12000 14000 m/z

9664 (4)

12070 (5)13219

14472 (6)

9000 10000 11000 12000 13000 14000 m/z

2332

29615923

3947 7898 118438883

2000 4000 6000 8000 10000 12000 14000 m/z

2050

2172 2332

2961

2595 3038 3158 3947

2000 2200 2400 2600 2800 3000 3200 3400 3600 3800 m/z

R=H, R’= -SO3K

C72H44N8O20S4K4Pt4

Average Mass: 2405

S-F MALDIDCTB matrix

S-B MALDIDCTB matrix

Loss of 2SO3K

Loss of 3SO3K S-F MALDI with DCTB as matrix

Replacement of 2K+ with H+ or Na+

1900 2000 2100 m/z

1900 2000 2100 m/z

2070 2090 2110 2130 2150 m/z

2125 2135 2145 21550

50

100

2132.3

2136.3 2138.3

2142.3Calc.

MALDI-mass spectra of heptanuclear Zn complex (R=C6H13) with DCTB matrix. Insert is the calculated isotope pattern of C90H114N6O25Zn7.

(M-OAc)+

M+.

Linear

Reflectron

MALDI-mass spectra of heptanuclear Zn complexes with DCTB matrix

(M-OAc)+

M+.

O

Zn

Zn

O O

O

ZnO

NZn

Zn

NOR

ORO

O

OOO

ZnN

O

O

NZn

NRO

ROO

O ZnN

O

OO O OORRO

Summary – SF-MALDI Opens up the analyses of compounds with

solubility issues.

Reduces the dependence on matrix solubility.

The vortex solvent-free sample preparation method works well, suggesting a good solid mixture being formed.

It produces same or higher quality mass spectral data.

Conclusions ASAP is a fast and easy method for direct

analysis for wide range of compounds using API (ESI or APCI) source on LCMS instruments.

SF-MALDI is a fast and easy sample preparation method that can produce the high quality MALDI mass spectra for wide variety of compounds.

Acknowledgements

Dr. Mark MacLachlanMarshall Lapawa Marco YeungDavid WongDerek Smith Work-Study Students

solvent-free sample preparation for api and maldi … wctow2013 ling.pdf · solvent-free sample...

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