Estudo de toners pretos na prespectiva da ciencia forens

Assis, Ana

Barbosa, Fatima

Custodio, Ana

Nabais, Joao

Tropecelo, Pedro

English

Repositório Científico da Universidade de Évora

Oral communication:Diamond cell Fourier Transform Infrared Spectroscopy Transmittance Analysis of Black Toners on Questioned DocumentsA. C. Almeida Assis1, M. F. Barbosa1, A. F. Custódio2, P. Tropecelo2, J.M. Valente Nabais21 Laboratório de Polícia Científica - Polícia Judiciária, Área Físico-Documental, Especialidade Forense de Documentos, Rua Gomes Freire, 174, 1169-007 Lisboa, Portugal2 Universidade de Évora, Escola de Ciências e Tecnologia, Centro de Química de Évora, Rua Romão Ramalho, 59, 7000-671 Évora, Portugal	This presentation will describe the use of Diamond cell Fourier Transform Infrared (FTIR) Spectroscopy methodology for the analysis of black toners commercialised in Portugal. A total of one hundred and thirty-eight different samples from eighteen manufacturers were analyzed in transmittance mode through a diamond cell. This methodology was considered to be non-destructive as it preserves the questioned documents’ integrity in the forensic analysis. The questioned documents support (paper sheets) does not influenciate the final result. This technique shows high repeatability and intermediate precision. Spectra were organized in twenty distinct groups based on its main chemical characteristics and relative peak intensity. A black toner infrared spectral library was developed. Spectral matches between forty-five blind samples and databases resulted in a 100% positive identification on the correct group.Poster:FTIR black toners analysis: ATR vs Diamond cellA. C. Almeida Assis1, M. F. Barbosa1, A. F. Custódio2, P. Tropecelo2, J.M. Valente Nabais21 Laboratório de Polícia Científica - Polícia Judiciária, Área Físico-Documental, Especialidade Forense de Documentos, Rua Gomes Freire, 174, 1169-007 Lisboa, Portugal2 Universidade de Évora, Escola de Ciências e Tecnologia, Centro de Química de Évora, Rua Romão Ramalho, 59, 7000-671 Évora, PortugalBlack toners are used in printing devices to produce copies or printed images. The use of efficient analytical methods for toner differentiation became very important in the forensic analysis due to the increasing rate of crime related with copied documents such as counterfeiting, fraud, anonymous letters, etc.In the present work we report a comparative study of Fourier Transform Infrared (FTIR) Spectroscopy black toners between Attenuated Total Reflectance (ATR) and diamond cell analysis.The ATR-FTIR analysis was performed with three crystals: Germanium, Silicium and Diamond.  The transmittance analysis was performed with a diamond cell.A variety of factors were analysed such as sample preparation, spectra quality, range of IR transparency, noise and consistency.This study provides data that clearly indicates diamond cell as the best technique for black toner analysis.

Black Toners on Questioned Documents

http://dspace.uevora.pt/rdpc/bitstream/10174/3911/1/Abstracts-IAFS%20Madeira%202011.doc

Black Toners on Questioned Documents

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Repositório Científico da Universidade de Évora