On the criteria for the discrimination of inkjet printer inks using micro‐Raman spectroscopy

Abstract

Inkjet printers are ubiquitous devices in our society. Therefore, it is not surprising that they are used to commit different types of illicit activities such as threats or extortions by means of anonymous letters, frauds in the context of disputed contracts, alterations to or counterfeit of ID documents, or counterfeit of currency banknotes. This latter application is of primary interest in this study, where a method to rapidly develop investigative leads is required. Inkjet printed documents produce microscopic colored dots that can be detected using a microscopical approach in conjunction with Raman spectroscopy. The overall goal of this project is to investigate if Raman data gathered from the three cyan, magenta, and yellow microscopic colored dots constitute, in conjunction, a chemical signature of sufficient discriminating quality to provide reliable investigative leads in a time‐effective and nondestructive manner. In the present phase of this study, the criteria necessary to achieve discriminations between inkjet printer inks from different manufacturers, the same manufacturers, and even the same models have been evaluated on a set of 11 samples. Although Raman spectroscopy is already a relatively well‐established method for the characterization of colorants (both dyes and pigments), this study demonstrates that the contribution of minor peaks within Raman spectra improves the discriminating capabilities of the technique. The joint consideration of the three colored components was also effective in differentiating inkjet printer ink samples, especially those from the same manufacturer and in some instances from the same model as well.

Recent advances in linear and nonlinear Raman spectroscopy. Part XIII

“…Buzzini and co‐workers discussed the criteria for the discrimination of inkjet printer inks using micro‐Raman spectroscopy. They concluded that although Raman spectroscopy is already a relatively well‐established method for the characterization of colourants (both dyes and pigments), this study demonstrates that the contribution of minor peaks within Raman spectra improves the discriminating capabilities of the technique . Jiao et al have provided solid confirmation for the origin of the low‐wave stray light in Raman spectra.…”

“…They concluded that although Raman spectroscopy is already a relatively well-established method for the characterization of colourants (both dyes and pigments), this study demonstrates that the contribution of minor peaks within Raman spectra improves the discriminating capabilities of the technique. [205] Jiao et al have provided solid confirmation for the origin of the lowwave stray light in Raman spectra. They confirmed that the stray light mentioned above originates from the grating secondary maxima of Rayleigh scattering experimentally and theoretically.…”

Interpol review of questioned documents 2016–2019

“…Buzzini P. and al [ 44 ]. discriminated coloured inkjet inks of different cartridge models using Raman spectroscopy.…”

Vibrational Spectroscopy and Chemometrics in Forensic Chemistry: Critical Review, Current Trends and Challenges

“…Buzzini et al 127 analyzed inkjet printed samples by Raman using two laser excitations, 532 and 785 nm, to reveal Raman signals which had been undetected by one of the lasers due to resonance effects. PCA was used for more objective discrimination of the inks involved, although the authors claimed that no improvements were achieved from a visual comparison of the spectra.…”