technology transition workshop dart mass spectrometry of writing inks roger jones midwest forensics...

Technology Transition Workshop

DART Mass Spectrometry of Writing Inks

Roger JonesMidwest Forensics Resource Center and

Ames Laboratory—USDOE,

Iowa State University

Midwest Forensics Resource Center


DART MS of Writing Inks• Comparison to Conventional Ink Analysis• Spectrum Acquisition

– Presentation of Sample

– Instrumental Conditions and Data Acquisition

– NIST Mass Spectral Search Program

• Interference from Paper• Effects of Writing Age

– Identification of Ink Components

• Ink Identification Using NIST Software


Comparison to Conventional Methods

• Optical Inspection– Side-by-side comparison under various

illuminations through various filters

– Strengths: Quick, cheap, non-destructive, often sufficient

– Weaknesses: Requires physical reference, provides minimal information, no library possible, cannot identify ink



• Thin Layer Chromatography– Side-by-side comparison, separates and

detects dyes and fluorescent components

– Strengths: Cheap, usually sufficient, more information than optical inspection, can build library, may identify ink

– Weaknesses: Slow, destructive, requires physical reference, sensitive to environment, less information than DART, requires physical sample library



• DART MS– Elemental formula determination of all volatile

and semi-volatile components

– Strengths: Quick, non-destructive, no physical reference, provides lots of information, database library, can identify ink, complementary to dye-sensitive methods

– Weaknesses: Expensive equipment, sensitive to vehicle, paper occasionally interferes


MS of Extracts vs. DART MS in Situ

0

50

100

0

50

100

Rel

ativ

e In

tens

ity (

m/z

372

= 1

00)

0

50

100

0

50

100

m/z

100 200 300 400 5000

50

100

Bic Wide Body

Bic Velocity

Bic Round Stic

Bic Cristal Grip

Bic Atlantis

372

358

m/z

100 200 300 400 5000

50

1000

50

100

Rel

ativ

e In

tens

ity (

m/z

139

= 1

00)

0

50

1000

50

1000

50

100 Bic Wide Body

Bic Velocity

Bic Round Stic

Bic Cristal Grip

Bic Atlantis

351

139

374

183

269

367

DART MS of Ink on Paper ESI-MS of Extracts5 Black Bic Ballpoints


Presentation of Sample

Modified Wikipedia image, with acknowledgement to JEOL USA, Inc., and author R. B. Cody


Full Page in Open Sample Holder


Sample Held by Cover-Plate Hook1/8-inch hole in cover plate gives access to sample.


Page in Closed Sample Holder


Sample in Position for Analysis


Modified Wikipedia image, with acknowledgement to JEOL USA, Inc., and author R. B. Cody

Instrumental Conditions

–3500 V +150 V

+650 V255 °C

3.25 L/min

He

Mount wired to spectrometer inlet

+20 V, 80 °C


Time (min)

0 1 2 3 4 5

Tot

al I

on C

ount

0.0

5.0e+6

1.0e+7

1.5e+7

2.0e+7

2.5e+7

3.0e+7

Blank Paper

Ink on Paper

PEG 600

Raw Spectra from Chromatogram

m/z

100 200 300 400 500 600

Inte

nsit

y (c

ount

s)

0

10000

20000

30000

40000

50000

279

269

315

359

m/z

100 200 300 400 500 600

Inte

nsit

y (c

ount

s)

0

10000

20000

30000

40000

50000

279

Zebra Rubber 80 Ballpoint on Hammermill Fore DP Paper

30 second averages


m/z

100 200 300 400 500 600

Inte

nsit

y (c

ount

s)

0

10000

20000

30000

40000

50000

279

269

315

359

Final Spectrum from Raw Spectra

m/z

100 200 300 400 500 600

Inte

nsit

y (c

ount

s)

0

10000

20000

30000

40000

50000

279

269

315

359

m/z

100 200 300 400 500 600

Inte

nsit

y (c

ount

s)

0

10000

20000

30000

40000

50000

279

Zebra Rubber 80 Ballpoint on Hammermill Fore DP Paper


DART MS of 3 Main Ink Types

m/z

100 200 300 4000

25

50

75

100

Rel

ativ

e In

tens

ity

0

25

50

75

100

0

25

50

75

100 Zebra Rubber 80Ballpoint

Bic Cristal Gel Roller

Mont BlancLe Grand Rollerball

359

150

139315

106 168 239

255

195

239

269

403100

121 283403


NIST Spectral Search Software• NIST Mass Spectral Search Program

– Demo Version 2.0d is a free download.

– Fully functional software with a small library

• Search Types– Spectral match; reverse/forward, with m/z limits,

identity/similarity, match ring number

– Search formula, name, CAS number, NIST registry number, peaks

– Constraints; molecular weight, elemental abundance, peak presence


NIST Spectrum Search Results

Unknown

List of matches

Spectrum of unknown

Spectrum of highlighted match

Distribution of matches Comparing unknown and highlighted match


Calculating Match Quality

2/1

2/1

1

)(

UL

UL

MAMA

AAMF

Match Quality, Q, combines two factors, F1 and F2, that range from 0 to 1.F1 is a mass-weighted dot product of the two spectra:

Sums are over M; M = m/z AL = relative intensity of library peakAU = relative intensity of unknown peak

From Stein, J. Am. Soc. Mass Spec., 1994, 5, 316.


Calculating Match Quality

2&1&

999FNFN

NNQ LUU

LUU

n

iU

iU

nN

i iL

iL

LU A

A

A

A

NF

LU

1,

,

2 1,

,

&2

&1

F2 compares ratios of successive peaks:

NU&L = number of peaks common to both unknown and library spectra. Sum is over those peaks.n = 1 if AL ratio < AU ratio, n = -1 if AU ratio < AL ratio.

Q is 999 for a perfect match.


Test of Paper Effects• Lines written freehand on 16 different types of

paper with three pens—1 ballpoint, 1 gel, 1 fluid ink.

• Stored in closed file in drawer for 8–9 months.• Three spectra acquired for each ink on each

paper. Samples handled with gloves.• All spectra for one ink placed in a NIST library.• All spectra searched against the library and

match qualities determined for each spectrum. Reverse matching with no m/z limit.


Papers Used in TestWhite Office Paper Envelopes

Champion Benefit Writing Brown Manila

Crane’s Resume White Ames Lab Letterhead

Great White Multipurpose 20

Hammermill Color Copy Miscellaneous Types

Hammermill Color Laser Gloss Ampad Evidence (ruled legal pad)

Hammermill Fore DP Colored paper, goldenrod

Hammermill Great White Copy Post-It Note, yellow

HP Color Inkjet Whatman #1 filter paper

Staples Copy Notepaper with printing under writing


Match Quality Index

5006007008009001000

Perc

ent o

f B

allp

oint

Sam

ples

0%

10%

20%

30%

Ballpoint Spectrum Match Qualities

Median Match Quality = 880

Distribution of Match Qualities of One Spectrum with45 Spectra of the Same Ink on Different Paper:

Black Zebra Rubber 80 Ballpoint Ink on Hammermill Fore

Hammermill Color Laser Gloss


Spectra Matching a Ballpoint Spectrum

m/z

100 200 300 400 500 6000

20

40

60

80

100

R

elat

ive

Inte

nsit

y0

20

40

60

80

1000

20

40

60

80

1000

20

40

60

80

100Hammermill Fore DP #1Unknown Being Matched

Manila Envelope #1Match Quality = 925

Best Match on Different Paper

Post-It Note #2Match Quality = 816

Worst Match Other ThanHammermill Laser Gloss

Hammermill Laser Gloss #1Match Quality = 548

Worst Match

Spectral Matching for a sample of Zebra Rubber 80 Black Ballpoint on Hammermill Fore DP Paper


Median Match Qualities for BallpointDistribution of Median Match Qualities with 45 Spectra

of the Same Ink on Different Paper:Black Zebra Rubber 80 Ballpoint Ink

Median Match Quality Index

5006007008009001000

Per

cent

of

Bal

lpoi

nt S

ampl

es

0%

10%

20%

30%

Hammermill Color Laser Gloss


Match Quality Index

5006007008009001000

Per

cent

of

Gel

-Ink

Sam

ples

0%

10%

20%

30%

Gel Ink Spectrum Match QualitiesDistribution of Match Qualities of One Spectrum with

45 Spectra of the Same Ink on Different Paper:Black Bic Cristal Gel Roller Ink on Hammermill Fore DP




5006007008009001000

Per

cent

of

Gel

-Ink

Sam

ples

0%

10%

20%

30%

Median Match Qualities for Gel InkDistribution of Median Match Qualities with 45 Spectra

of the Same Ink on Different Paper:Black Bic Cristal Gel Roller Ink


Fluid Ink Spectrum Match Qualities

Match Quality Index

5006007008009001000

Perc

ent o

f Fl

uid-

Ink

Sam

ples

0%

10%

20%

30%

Distribution of Match Qualities of One Spectrum with45 Spectra of the Same Ink on Different Paper:

Blue Mont Blanc Le Grand Roller Ink on Hammermill Fore




5006007008009001000

Per

cent

of

Flu

id-I

nk S

ampl

es

0%

10%

20%

30%

H. Color Laser GlossCrane's Resume

Median Match Qualities for Fluid InkDistribution of Median Match Qualities with 45 Spectra

of the Same Ink on Different Paper:Blue Mont Blanc Le Grand Rollerball Ink


Effects of Writing Age• Lines written freehand periodically on white

copy paper (Hammermill Fore DP).• Stored in closed folder in desk drawer with

blank pages surrounding each written page.• Samples handled with gloves during analysis.• Three spectra at each age averaged for time

plots.


Black Bic Round Stic Ballpoint at Two Ages

m/z

100 200 300 4000

50

100

150

200

Rel

ativ

e In

tens

ity

(m/z

367

= 1

00)

0

50

100

150

200

269100

351139

199

183

165200

139

351269

183

100

4 Days Old

332 Days Old

367

165

367

374

374


Components of Bic BallpointObserved

m/zChemical Formula

Actual m/z

Most Probable Identity

100.076 [C5H9NO+H]+ 100.076 N-methyl-2-pyrrolidone

139.076 [C8H10O2+H]+ 139.076 Phenoxyethanol

165.094 [C10H12O2+H]+ 165.092 Various fragrant liquids

183.102 [C10H14O3+H]+ 183.102 Diethylene glycol monophenyl ether

199.142 [C11H18O3+H]+ 199.133 Various fragrant liquids

269.166 [C17H20N2O+H]+ 269.166 Michler’s ketone

351.215 uncertain ---- ----

367.210 [C20H30O6+H]+ 367.212 Dibutylglycol phthalate

374.264 [C25H30N3+2H]+ 374.260 Crystal violet


Crystal Violet Cationic Dye


m/z

300 320 340 360 380 400 420 440

Rel

avti

ve I

nten

sity

(m

/z 3

72 =

100

)

0

20

40

60

80

100

120

372.242

374.259

358.232 390.260

404.237345.205

[Crystal Violet]+

[Crystal Violet + 2H]+

[Methyl Violet]+

[Crystal Violet + O ]2+

[Crystal Violet + H O] +2

Crystal Violet DART Spectrum


Aging of Black Bic Round Stic Ballpoint

Age (days)

0 100 200 3000

50

100

150m/z 165 m/z 183 m/z 269 m/z 351

Rel

ativ

e In

tens

ity

(m/z

367

= 1

00)

0

50

100

150

200

250

300

m/z 100 m/z 139 m/z 199


Black Bic Cristal Gel Roller Ink at Two Ages

m/z

100 150 200 250 300 350 4000

20

40

60

80

100

Rel

ativ

e In

tens

ity

(m/z

150

= 1

00)

0

20

40

60

80

100

239106

150

148

195

151

168195

150

301

239

151

106

9 Days Old

336 Days Old

148 168


Components of Bic Gel InkObserved

m/zChemical Formula

Actual m/z

Most Probable Identity

106.088 [C4H11NO2+H]+ 106.087 Diethanolamine

148.100 C7H16O3+ 148.110 Dipropylene glycol monomethyl ether

150.114 [C6H15NO3+H]+ 150.113 Triethanolamine

151.102 [C6H14O4+H]+ 151.097 Triethylene glycol

168.127 C10H16O2+ 168.115 Dipentene diepoxide

195.124 [C8H18O5+H]+ 195.123 Tetraethylene glycol

239.151 [C10H22O6+H]+ 239.149 Pentaethylene glycol

301.186 [C18H24N2O2+H]+

or [C19H24O3+H]+

301.192

301.180----


Aging of Black Bic Cristal Gel Roller Ink

Age (days)

0 100 200 3000

10

20

30m/z 106 m/z 168 m/z 195 R

elat

ive

Inte

nsit

y (m

/z 1

50 =

100

)

0

10

20

30

40

50

60

70 m/z 148 m/z 151 m/z 239 m/z 301


BlueMont Blanc Le Grand Rollerball Fluid Ink at Two Ages

m/z

100 200 300 400 5000

20

40

60

80

100

Rel

ativ

e In

tens

ity (

m/z

239

= 1

00)

0

20

40

60

80

100239

121 195

256

255256

283

300299

327

343

344

327299

300

283239

195

121387

4 Days Old

340 Days Old

371

151

151150

212

212211 388

432431

415

476475

403


BlueMont Blanc Le Grand Rollerball Fluid Ink at Two Ages

m/z

100 200 300 400 5000

20

40

60

80

100

Rel

ativ

e In

tens

ity

(m/z

239

= 1

00)

0

20

40

60

80

100239

121 195

256

255256

283

300299

327

343

344

327299

300

283239

195

121387

4 Days Old

340 Days Old

371

151

151150

212

212211 388

432431

415

476475

403


Components of Mont Blanc InkObserved m/z Chemical Formula Probable Identity

121.075 [C8H8O+H]+ Acetophenone

403.193 Not determined Not in ink

151.101, 195.126, 239.152, 283.178, 327.207, 371.233, 415,254

[HO(C2H4O)nH+H]+

n = 3 to 9

Polyethylene glycols

211.132, 255.159, 299.185, 343.214, 387.243, 431.267, 475.292

[C8H10O(C2H4O)n+H]+ n = 3 to 9

Polyethylene glycol ethyl phenyl diethers

212.154, 256.179, 300.206, 344.231, 388.257, 432.288, 476.313

C16H20(C2H4O)n+ or

C7H12N2(C2H4O)m+ n

= 0 to 6, m = 2 to 8

Polyethylene glycol derivatives


Aging of Blue Mont BlancLe Grand Rollerball Fluid Ink

Age (days)

0 100 200 3000

20

40

60

80m/z 195 m/z 300 m/z 327 m/z 343 m/z 344 m/z 403

Rel

ativ

e In

tens

ity (

m/z

239

= 1

00)

0

20

40

60

80

100m/z 121 m/z 255 m/z 256 m/z 283 m/z 299


Ink Identification• Library of 166 inks: 76 ballpoints, 50 fluid inks

and 40 gel inks.• Written 10 to 35 months before testing.• 2 spectra of each ink placed in NIST library for

the correct ink type. Handled with gloves.• Every spectrum tested as an unknown.

– Perfect match with self is ignored, so Hit #1 is next best match

• Ink correctly identified if Hit #1 is the other spectrum for the same ink.


Ink Identification Test Results

Ink

Type

Black Inks Blue Inks

No. of Inks in Library

Correct Identifications

No. of Inks in Library

Correct Identifications

Ballpoint 48 99% 28 100%

Fluid 26 81% 24 77%

Gel 21 93% 19 97%

All (black & blue)

166 92% -- --


Unknowns that Matched Incorrectly

• Black Ballpoints – 1 error– PaperMate Flexgrip Elite matched Papermate

Flexgrip Ultra

• Blue Ballpoints – 0 errors• Black Gels – 3 errors

– 2 Pentel Sunburst Gels matched a Parker Gel Refill and an Integra Roller Gel

– Zebra Jell 3 matched Parker Gel Refill

• Blue Gels – 1 error– Pentel Hybrid H2 matched Pentel Sunburst Gel


Unknowns that Matched Incorrectly

• Black Fluids – 10 errors

2 PaperMate Liquid Expresso Staedtler Silver Ball 404

Pilot Precise Rolling Ball Uni-ball Deluxe Roller

Sheaffer Slim Rollerball Refill Uni-ball Vision Roller

Staedtler Lumocolor 2 Waterman RollerBall Refill

Bic Z4 Parker Roller Ball Refill

2 Cross Porous Tip Refill 2 Sheaffer Slim Rollerball Refill

2 PaperMate Flair 2 Zebra Zeb-Roller 2000

PaperMate Liquid Expresso

• Blue Fluids – 11 errors


Forward-Matching Match Qualities

5006007008009001000

0%

3%

6%

9%

12%

Per

cent

age

of M

atch

es

0%

10%

20%

30% Correct Match

Closest Incorrect Match

Match Quality of Correct and Closest Incorrect Matches for Black Ballpoints



4005006007008009001000

0%

3%

6%

9%

12%

Per

cent

age

of M

atch

es

0%

5%

10%

15%

20%Correct Match


under400

Match Quality of Correct and Closest Incorrect Matches for Blue Ballpoints



4006008001000

0%

3%

6%

9%

12%

Per

cent

age

of M

atch

es

0%

5%

10%

15%

20% Correct Match


under300

Match Quality of Correct and Closest Incorrect Matches for Black Gel Inks

Pentel Sunburst



4005006007008009001000

0%

3%

6%

9%

12%

Per

cent

age

of M

atch

es

0%

10%

20%

30% Correct Match


under400

Match Quality of Correct and Closest Incorrect Matches for Black Fluid Inks


Match Qualities in Ink Identification

Ink TypeCorrect Match Closest Incorrect

MatchDifference Between Correct & Incorrect

Average Median Average Median Average Median

Black Ballpoint

882.3 888.5 749.7 750.0 138.4 119.0

Blue Ballpoint

878.0 884.0 626.0 620.5 252.0 249.0

Black Fluid

773.2 792.5 647.7 695.0 125.5 83.0

Blue Fluid 702.3 743.5 563.7 592.0 138.6 130.0

Black Gel 793.9 832.0 609.0 602.5 188.3 155.5

Blue Gel 752.2 719.0 590.3 560.5 152.7 125.0


Acknowledgements• National Institute of Justice

– This project was supported by Award No. 2006-DN-BX-K017 awarded by the National Institute of Justice, Office of Justice Programs, US Department of Justice. The opinions, findings, and conclusions or recommendations expressed in this exhibition are those of the author and do not necessarily reflect the views of the Department of Justice.

• John McClelland, principal investigator• Susan Lorge, worked out optimum conditions

and acquired library data

technology transition workshop dart mass spectrometry of writing inks roger jones midwest forensics...

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