Fast and unequivocal methods of questioned document analysis are essential in forensic science. Here, a desorption/ionization technique, EASI-MS, was assessed for its ability to investigate questioned driver’s licenses (DL). Two suspects DL, displaying the same personal data in the proper fields (name and ID numbers), but with different individual photos, showing similar impressions on microscopic analysis, and authentic standards documents specimens were used as test cases. Profiles from authentic DL surface were dominated by a set of few minor ions, mainly from the plasticizers bis(2-ethylhexyl)phthalate and dibutylphthalate. The seized suspect counterfeit DL on points from personal data and photo were, however, dominated by abundant diagnostic ions of m/z 463, 507, 551, 595, 639, 683, which confirmed counterfeiting. Surfynol® and Nonoxynol-9®, which are common constituents of inkjet printing, were detected in the counterfeiting areas by high-accuracy EASI(+)-FT-ICR MS. The EASI-MS technique is shown therefore to offer an attractive tool for forensic investigation of questioned documents.
The analysis of potentially forged printed documents, such as driver’s licenses, is an important area in forensic science [
In forensic investigations, the use of nondestructive methods of screening and the acquisition of molecular data is crucial to produce unequivocal evidence. To date, diverse analytic methodologies have been applied. For example, FTIR [
Recently, a new class of ionization techniques for ambient mass spectrometry [
In this study, we examined the ability of EASI-MS to identify a real and challenging case of document forgery. In this case, printed data were added to an original blank driver’s license, on which all of the security items were present, thus constituting illegal data insertion.
HPLC-grade methanol and formic acid were purchased from Burdick & Jackson (Muskegon, MI). Two suspect driver’s licenses were provided by Dr. Octávio Eduardo de Brito Alvarenga at the Criminalistic Institute, Technical-Scientific Police Superintendency from São Paulo State, Brazil. The two driver’s licenses displayed the same personal data in the proper fields (name and ID numbers) but had different individual photos and showed relatively similar impressions on microscopic analysis. The authentic license of the owner was provided by the police investigators, but the forged license was of high quality and could not be clearly identified using the existing standard methods. A set of three samples of authentic driver’s licenses were analyzed for comparison with the two seized samples.
Experiments were initially performed on a single quadrupole mass spectrometer (LCMS-2010EV; Shimadzu Corp., Kyoto, Japan) equipped with a home-made easy ambient sonic-spray ionization (EASI) source (
As
repeating units. The EASI(+)-MS chemical profile of the blank document in the seized driver’s license (
The forged samples were also analyzed by EASI(+)-FT-ICR MS, as shown in
The ions of m/z 284 [C19H42N]+, m/z 368 [C25H54N]+, m/z 494 [C34H72N]+, m/z 522 [C36H76N]+, and m/z 550 [C38H80N]+ were attributed to quaternary ammonium cations (
The EASI(+)-FT-ICR spectra of the forged document showed diverse and characteristic chemical profiles (
m/z | Relative abundance | Theoretical mass | Error (ppm) | Formula | Identification |
---|---|---|---|---|---|
550.62961 | 100 | 550.6285 | 1.97 | [C38H80N]+ | [QAC]+ |
413.26708 | 96.62 | 413.2662 | 2.06 | [C24H38O4Na]+ | [DEHP-Na]+ |
522.59825 | 83.29 | 522.5972 | 1.95 | [C36H76N]+ | [QAC]+ |
284.33167 | 62.15 | 284.3312 | 1.75 | [C19H42N]+ | [QAC]+ |
429.24109 | 53.88 | 429.2402 | 2.15 | [C24H38O4K]+ | [DEHP-K]+ |
803.54535 | 32.37 | 803.5432 | 2.62 | [C48H76O8Na]+ | [2DEHP-Na]+ |
494.56688 | 26.35 | 494.5659 | 1.92 | [C34H72N]+ | [QAC]+ |
368.42576 | 24.32 | 368.4251 | 1.84 | [C25H54N]+ | [QAC]+ |
301.14155 | 21.02 | 301.1410 | 1.71 | [C16H22O4Na]+ | [DBP-Na]+ |
391.28515 | 12.98 | 391.2843 | 2.22 | [C24H39O4]+ | [DEHP-H]+ |
819.51931 | 5.23 | 819.5172 | 2.6 | [C48H76O8K]+ | [2DEHP-K]+ |
QAC: quaternary ammonium cations; DBP: dibutyl phthalate; DEHP: bis(2-ethylhexyl)phthalate.
Experimental m/z | Relative abundance | Theoretical m/z | Error (ppm) | Predict formula | Identification |
---|---|---|---|---|---|
485.34812 | 7.64 | 485.3473 | 1.72 | C27H49O7 | Protonated Nonoxynol-9 |
529.37442 | 13.11 | 529.3735 | 1.75 | C29H53O8 | |
573.40066 | 14.43 | 573.3997 | 1.66 | C31H57O9 | |
617.42702 | 11.16 | 617.4259 | 1.78 | C33H61O10 | |
661.45323 | 7.76 | 661.4521 | 1.65 | C35H65O11 | |
590.42732 | 42.87 | 590.4263 | 1.80 | C31H56O9NH4 | Ammoniated Nonoxynol-9 |
634.45358 | 61.58 | 634.4525 | 1.74 | C33H60O10NH4 | |
678.47984 | 72.80 | 678.4787 | 1.69 | C35H64O11NH4 | |
722.50616 | 65.57 | 722.5049 | 1.74 | C37H68O12NH4 | |
766.53242 | 51.56 | 766.5311 | 1.70 | C39H72O13NH4 | |
551.35638 | 80.65 | 551.3554 | 1.71 | C29H52O8Na | Sodiated Nonoxynol-9 |
595.38266 | 89.27 | 595.3817 | 1.69 | C31H56O9Na | |
639.40897 | 100.00 | 639.4079 | 1.72 | C33H60O10Na | |
683.43529 | 91.98 | 683.4341 | 1.76 | C35H64O11Na | |
727.46161 | 70.39 | 727.4603 | 1.80 | C37H68O12Na | |
567.33034 | 46.55 | 567.3294 | 1.69 | C29H52O8K | Potassiated Nonoxynol-9 |
611.35661 | 83.73 | 611.3556 | 1.66 | C31H56O9K | |
655.38292 | 98.95 | 655.3818 | 1.71 | C33H60O10K | |
699.4092 | 90.39 | 699.4080 | 1.68 | C35H64O11K | |
743.43561 | 74.41 | 743.4342 | 1.85 | C37H68O12K | |
513.34053 | 12.04 | 513.3398 | 1.44 | C26H50O8Na | Sodiated Surfynol |
557.36693 | 19.00 | 557.3660 | 1.66 | C28H54O9Na | |
601.39329 | 22.22 | 601.3922 | 1.79 | C30 H58O10Na | |
645.41951 | 23.04 | 645.4184 | 1.66 | C32H62O11Na | |
689.44577 | 16.55 | 689.4447 | 1.63 | C34H66O12Na |
of ions separated by 44 m/z units (
In this case study of counterfeit driver’s licenses, EASI(+)-MS provided a direct, rapid, robust, non-destructive and reliable molecular fingerprinting method to screen for authenticity of printed documents. The illegally inserted personal data and photo could be easily distinguished from the original printed areas, which matched those of authentic driver’s licenses. The counterfeiting process was also inferred from the characterization of typical constituents of the ink used. In this case, the data suggested the use of an inkjet printer. The simple design of an EASI source uses readily available laboratory parts and, therefore, can be easily implemented on most mass spectrometers using API sources. This rapid and inexpensive implementation in forensic laboratories equipped with such instruments makes routine analysis of questionable printed documents possible.
We thank CAPES―Coordenação de Aperfeiçoamento de Pessoal de Nível Superior―for financial support (pro- cess No. 23038.006844/2014-46) and also the National Institute of Metrology, Quality and Technology, INMETRO, Brazilian Federal Police, PF, and Technical-Scientific Police Superintendence, Criminalistic Institute from São Paulo, IC-SPTC-SP, for provide samples and assistance.
Deleon Nascimento Correa,Eduardo Morgado Schmidt,Marcos Fernando Franco,Jorge Jardim Zacca,Werickson Fortunato de Carvalho Rocha,Antony de Paula Barbosa,Rodrigo Borges,Wanderley de Souza,Marcos Nogueira Eberlin, (2016) Analyzing Brazilian Driver’s License Authenticity by Easy Ambient Sonic-Spray Ionization Mass Spectrometry. American Journal of Analytical Chemistry,07,342-350. doi: 10.4236/ajac.2016.74032