Counterfeit one hundred Malaysian ringgit banknotes discrimination using chemical imaging inspection and pattern recognition

Counterfeit currency can have detrimental effects on the economy of a country. The effects include inflation, as well as black marketing and misfortunes to commerce and administrations. This study analyzed the genuine and confiscated counterfeit Malaysian RM100 banknotes using Video Spectral Comparator (VSC), chemical profiling using Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) and pattern recognition techniques of Principal Component Analysis (PCA) and Partial Linear Square-Discriminant Analysis (PLS-DA). VSC analysis revealed substantial morphological variations in the confiscated counterfeit samples than that of the genuine banknotes, as well as the standards prescribed by the Bank Negara Malaysia. ATR-FTIR analysis further revealed marked differences in the spectra between the counterfeit and the genuine banknotes, particularly in the fingerprint region of 1800–650 cm−1. While the PCA and PLS-DA successfully discriminated the genuine and counterfeit banknotes, further analysis on the counterfeit samples alone failed to categorically discriminate them into separate groups. Therefore, the fact that the counterfeit banknotes may originate from the same common source cannot be overruled, consistent with the relatively small circulation of the Malaysian currency. The procedure of using the non-destructive ATR-FTIR in combination with chemometrics techniques utilized here may prove useful for unveiling the current trends, as well as developing prediction ability to investigate future encounters of counterfeited Malaysian banknotes