Technology Transition Workshop DART Mass Spectrometry of Writing Inks Roger Jones Midwest Forensics Resource Center and Ames Laboratory—USDOE, Iowa State University Midwest Forensics Resource Center Technology Transition Workshop 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 Technology Transition Workshop 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 Technology Transition Workshop Comparison to Conventional Methods • 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 Technology Transition Workshop Comparison to Conventional Methods • 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 Technology Transition Workshop MS of Extracts vs. DART MS in Situ DART MS of Ink on Paper 139 100 Bic Wide Body 183 50 351 269 0 100 100 0 100 Bic Velocity 50 0 100 Bic Round Stic 50 0 100 Bic Cristal Grip 50 0 100 Bic Wide Body 372 50 374 Relative Intensity (m/z 372 = 100) Relative Intensity (m/z 139 = 100) 367 ESI-MS of Extracts 5 Black Bic Ballpoints Bic Velocity 50 0 100 Bic Round Stic 50 0 100 Bic Cristal Grip 50 0 100 Bic Atlantis 358 Bic Atlantis 50 50 0 0 100 200 300 m/z 400 500 100 200 300 m/z 400 500 Technology Transition Workshop Presentation of Sample Modified Wikipedia image, with acknowledgement to JEOL USA, Inc., and author R. B. Cody Technology Transition Workshop Full Page in Open Sample Holder Technology Transition Workshop Full Page in Open Sample Holder Technology Transition Workshop Sample Held by Cover-Plate Hook 1/8-inch hole in cover plate gives access to sample. Technology Transition Workshop Page in Closed Sample Holder Technology Transition Workshop Sample in Position for Analysis Technology Transition Workshop Instrumental Conditions Mount wired to spectrometer inlet –3500 V +150 V 3.25 L/min He 255 °C +650 V +20 V, 80 °C Modified Wikipedia image, with acknowledgement to JEOL USA, Inc., and author R. B. Cody Technology Transition Workshop Raw Spectra from Chromatogram Zebra Rubber 80 Ballpoint on Hammermill Fore DP Paper Intensity (counts) 50000 40000 30000 20000 279 10000 0 269 40000 315 30000 279 20000 359 10000 0 100 200 300 400 500 600 100 200 300 m/z 3.0e+7 Total Ion Count Intensity (counts) 50000 400 500 m/z PEG 600 2.5e+7 30 second averages 2.0e+7 1.5e+7 Ink on Paper 1.0e+7 Blank Paper 5.0e+6 0.0 0 1 2 3 Time (min) 4 5 600 Technology Transition Workshop Final Spectrum from Raw Spectra Zebra Rubber 80 Ballpoint on Hammermill Fore DP Paper Intensity (counts) 50000 40000 30000 20000 279 10000 269 40000 315 30000 279 20000 359 10000 0 0 100 200 300 400 500 600 100 200 m/z 50000 Intensity (counts) Intensity (counts) 50000 300 m/z 269 40000 315 30000 359 20000 279 10000 0 100 200 300 m/z 400 500 600 400 500 600 Technology Transition Workshop DART MS of 3 Main Ink Types 100 75 50 Relative Intensity 25 269 Zebra Rubber 80 Ballpoint 255 315 359 403 100 139 0 100 150 Bic Cristal Gel Roller 75 50 25 106 168 239 0 100 239 75 50 121 195 Mont Blanc Le Grand Rollerball 283 25 403 0 100 200 300 m/z 400 Technology Transition Workshop 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 Technology Transition Workshop NIST Spectrum Search Results Distribution of matches Comparing unknown and highlighted match Unknown Spectrum of unknown List of matches Spectrum of highlighted match Technology Transition Workshop Calculating Match Quality 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: 1/ 2 M ( A A ) L U F1 1/ 2 MAL MAU Sums are over M; M = m/z AL = relative intensity of library peak AU = relative intensity of unknown peak From Stein, J. Am. Soc. Mass Spec., 1994, 5, 316. Technology Transition Workshop Calculating Match Quality F2 compares ratios of successive peaks: 1 F2 NU & L i 2 NU & L AL ,i A L ,i 1 n AU ,i A U ,i 1 n 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. 999 NU F1 NU & L F2 Q NU NU & L Q is 999 for a perfect match. Technology Transition Workshop 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. Technology Transition Workshop Papers Used in Test White 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 Technology Transition Workshop Ballpoint Spectrum Match Qualities Percent of Ballpoint Samples Distribution of Match Qualities of One Spectrum with 45 Spectra of the Same Ink on Different Paper: Black Zebra Rubber 80 Ballpoint Ink on Hammermill Fore Median Match Quality = 880 30% 20% 10% 0% 1000 Hammermill Color Laser Gloss 900 800 700 Match Quality Index 600 500 Technology Transition Workshop 100 Unknown Being Matched Hammermill Fore DP #1 80 Spectral Matching for a sample of Zebra Rubber 80 Black Ballpoint on Hammermill Fore DP Paper 40 20 0 100 Best Match on Different Paper Manila Envelope #1 Match Quality = 925 80 60 Relative Intensity Spectra Matching a Ballpoint Spectrum 60 40 20 0 100 Worst Match Other Than Hammermill Laser Gloss Post-It Note #2 Match Quality = 816 80 60 40 20 0 100 Worst Match Hammermill Laser Gloss #1 Match Quality = 548 80 60 40 20 0 100 200 300 m/z 400 500 600 Technology Transition Workshop Median Match Qualities for Ballpoint Percent of Ballpoint Samples Distribution of Median Match Qualities with 45 Spectra of the Same Ink on Different Paper: Black Zebra Rubber 80 Ballpoint Ink 30% 20% 10% 0% 1000 Hammermill Color Laser Gloss 900 800 700 Median Match Quality Index 600 500 Technology Transition Workshop Gel Ink Spectrum Match Qualities Percent of Gel-Ink Samples Distribution 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 Median Match Quality = 854 30% 20% 10% 0% 1000 900 800 700 Match Quality Index 600 500 Technology Transition Workshop Median Match Qualities for Gel Ink Percent of Gel-Ink Samples Distribution of Median Match Qualities with 45 Spectra of the Same Ink on Different Paper: Black Bic Cristal Gel Roller Ink 30% 20% 10% 0% 1000 900 800 700 Median Match Quality Index 600 500 Technology Transition Workshop Fluid Ink Spectrum Match Qualities Percent of Fluid-Ink Samples Distribution of Match Qualities of One Spectrum with 45 Spectra of the Same Ink on Different Paper: Blue Mont Blanc Le Grand Roller Ink on Hammermill Fore Median Match Quality = 777 30% 20% 10% 0% 1000 900 800 700 Match Quality Index 600 500 Technology Transition Workshop Median Match Qualities for Fluid Ink Percent of Fluid-Ink Samples Distribution of Median Match Qualities with 45 Spectra of the Same Ink on Different Paper: Blue Mont Blanc Le Grand Rollerball Ink 30% 20% H. Color Laser Gloss Crane's Resume 10% 0% 1000 900 800 700 Median Match Quality Index 600 500 Technology Transition Workshop 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. Technology Transition Workshop 200 332 Days Old Black Bic Round Stic Ballpoint at Two Ages Relative Intensity (m/z 367 = 100) 150 183 367 100 139 351 50 165 100 200 0 200 374 269 199 4 Days Old 139 100 150 367 183 100 351 269 50 374 165 0 100 200 300 m/z 400 Technology Transition Workshop Components of Bic Ballpoint Observed m/z 100.076 139.076 165.094 183.102 Chemical Formula Actual m/z Most Probable Identity 100.076 N-methyl-2-pyrrolidone 139.076 Phenoxyethanol 165.092 Various fragrant liquids [C5H9NO+H]+ [C8H10O2+H]+ [C10H12O2+H]+ [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 Technology Transition Workshop Crystal Violet Cationic Dye Technology Transition Workshop Relavtive Intensity (m/z 372 = 100) Crystal Violet DART Spectrum 120 [Crystal Violet] + 372.242 100 [Crystal Violet + 2H] + 374.259 80 60 [Methyl Violet] + 358.232 40 [Crystal Violet + H2O] + 390.260 [Crystal Violet + O2] + 404.237 345.205 20 0 300 320 340 360 380 m/z 400 420 440 Technology Transition Workshop 300 Aging of Black Bic Round Stic Ballpoint Relative Intensity (m/z 367 = 100) 250 m/z 100 m/z 139 m/z 199 200 150 100 50 0 m/z 165 m/z 183 m/z 269 m/z 351 150 100 50 0 0 100 200 Age (days) 300 Technology Transition Workshop 150 100 336 Days Old Black Bic Cristal Gel Roller Ink at Two Ages Relative Intensity (m/z 150 = 100) 80 60 40 151 148 20 168 106 0 100 195 239 150 9 Days Old 80 151 60 301 40 195 20 148 239 168 106 0 100 150 200 250 m/z 300 350 400 Technology Transition Workshop Components of Bic Gel Ink Observed m/z Chemical Formula 106.088 [C4H11NO2+H]+ 148.100 C7H16O3+ 150.114 [C6H15NO3+H]+ 151.102 [C6H14O4+H]+ Actual m/z Most Probable Identity 106.087 Diethanolamine 148.110 Dipropylene glycol monomethyl ether 150.113 Triethanolamine 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 Technology Transition Workshop m/z 148 m/z 151 m/z 239 m/z 301 70 Aging of Black Bic Cristal Gel Roller Ink Relative Intensity (m/z 150 = 100) 60 50 40 30 20 10 30 0 m/z 106 m/z 168 m/z 195 20 10 0 0 100 200 Age (days) 300 Technology Transition Workshop 100 340 Days Old 239 Blue Mont Blanc Le Grand Rollerball Fluid Ink at Two Ages Relative Intensity (m/z 239 = 100) 80 60 40 195 121 283 256 20 403 300 299 212 151 0 100 327 239 4 Days Old 283 80 195 60 40 121 343 327 299 256 300 255 20 150 151 0 100 200 344 387 388 431 432 476 475 371 415 212 211 300 m/z 400 500 Technology Transition Workshop 100 340 Days Old 239 Blue Mont Blanc Le Grand Rollerball Fluid Ink at Two Ages Relative Intensity (m/z 239 = 100) 80 60 40 195 121 283 256 20 403 300 299 212 151 0 100 327 239 4 Days Old 283 80 195 60 40 121 343 327 299 256 300 255 20 150 151 0 100 200 344 387 388 431 432 476 475 371 415 212 211 300 m/z 400 500 Technology Transition Workshop Components of Mont Blanc Ink Observed m/z Chemical Formula 121.075 [C8H8O+H]+ 403.193 Not determined 151.101, 195.126, 239.152, 283.178, 327.207, 371.233, 415,254 Probable Identity Acetophenone Not in ink [HO(C2H4O)nH+H]+ Polyethylene glycols n = 3 to 9 211.132, 255.159, 299.185, [C8H10O(C2H4O)n+H] Polyethylene + n = 3 to 9 343.214, 387.243, 431.267, glycol ethyl phenyl 475.292 diethers 212.154, 256.179, 300.206, C16H20(C2H4O)n+ or Polyethylene 344.231, 388.257, 432.288, C7H12N2(C2H4O)m+ glycol derivatives 476.313 n = 0 to 6, m = 2 to 8 Technology Transition Workshop 100 m/z 121 m/z 255 m/z 256 m/z 283 m/z 299 Aging of Blue Mont Blanc Le Grand Rollerball Fluid Ink Relative Intensity (m/z 239 = 100) 80 60 40 20 0 m/z 195 m/z 300 m/z 327 m/z 343 m/z 344 m/z 403 80 60 40 20 0 0 100 200 Age (days) 300 Technology Transition Workshop 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. Technology Transition Workshop Ink Identification Test Results Ink Type Black Inks Blue Inks No. of Inks Correct No. of Inks Correct in Library Identifications in Library Identifications Ballpoint 48 99% 28 100% Fluid 26 81% 24 77% Gel 21 93% 19 97% All (black & blue) 166 92% -- -- Technology Transition Workshop 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 Technology Transition Workshop 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 • Blue Fluids – 11 errors 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 Technology Transition Workshop Correct Match 30% 20% Percentage of Matches Match Quality of Correct and Closest Incorrect Matches for Black Ballpoints 10% 0% Closest Incorrect Match 12% 9% 6% 3% 0% 1000 900 800 700 600 Forward-Matching Match Qualities 500 Technology Transition Workshop Correct Match 20% 15% Percentage of Matches Match Quality of Correct and Closest Incorrect Matches for Blue Ballpoints 10% 5% 0% 12% Closest Incorrect Match 9% 6% 3% 0% 1000 900 800 700 600 500 Forward-Matching Match Qualities under 400 400 Technology Transition Workshop 20% 15% Percentage of Matches Match Quality of Correct and Closest Incorrect Matches for Black Gel Inks Correct Match 10% Pentel Sunburst 5% 0% 12% Closest Incorrect Match 9% 6% 3% 0% 1000 800 600 400 Forward-Matching Match Qualities under 300 Technology Transition Workshop 30% 20% Percentage of Matches Match Quality of Correct and Closest Incorrect Matches for Black Fluid Inks Correct Match 10% 0% Closest Incorrect Match 12% 9% 6% 3% 0% 1000 900 800 700 600 500 Forward-Matching Match Qualities under 400 400 Technology Transition Workshop Match Qualities in Ink Identification Ink Type Correct Match Closest Incorrect Match Difference Between Correct & Incorrect Average Median Average Median Average Median Black Ballpoint Blue Ballpoint Black Fluid 882.3 888.5 749.7 750.0 138.4 119.0 878.0 884.0 626.0 620.5 252.0 249.0 773.2 792.5 647.7 695.0 125.5 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 Technology Transition Workshop Acknowledgements • National Institute of Justice – This project was supported by Award No. 2006-DNBX-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