Portable XRF and principal component analysis for bill characterization in forensic science

• The paper is about a direct method for bills discrimination by EDXRF and principal component analysis.
• The bills are analyzed directly, without sample preparation and non destructively.
• The results demonstrates that the methodology is feasible and could be applied in forensic science for identification of origin and false banknotes.
• The novelty is that portable EDXRF is very fast and efficient for bills characterization.

Several modern techniques have been applied to prevent counterfeiting of money bills. The objective of this study was to demonstrate the potential of Portable X-ray Fluorescence (PXRF) technique and the multivariate analysis method of Principal Component Analysis (PCA) for classification of bills in order to use it in forensic science. Bills of Dollar, Euro and Real (Brazilian currency) were measured directly at different colored regions, without any previous preparation. Spectra interpretation allowed the identification of Ca, Ti, Fe, Cu, Sr, Y, Zr and Pb. PCA analysis separated the bills in three groups and subgroups among Brazilian currency. In conclusion, the samples were classified according to its origin identifying the elements responsible for differentiation and basic pigment composition. PXRF allied to multivariate discriminate methods is a promising technique for rapid and no destructive identification of false bills in forensic science.