Spectral harmonization of Raman data for reliable anti-counterfeiting analysis

Interoperability, understood as the ability of instruments to exchange, compare and integrate Raman spectra acquires from different instruments, is one of the major challenges across different laboratories, centers or industries. Among the various fields aiming for interoperability and harmonization between instruments, detecting counterfeiting in high-value documents is a key application. Therefore, the main objective of this work is to establish a feasible approach to harmonize different Raman systems to enable the comparison of Raman spectra within the context of counterfeit detection. The goal is to ensure that different Raman systems produce equivalent results, thereby fostering interoperability among Raman instruments. The proposed method has been validated using two excitation laser wavelengths (785 and 532 nm) and two different materials (potassium‑sodium niobate and polystyrene) applied to a particular case study. A chemometric study based on Principal Component Analysis (PCA) was also performed to study the reproducibility of the analysis. The main results demonstrate that it is possible to obtain comparable Raman spectra in terms of intensity for both organic and inorganic materials, as well as for the security markers as demonstrators proposed in this work. Furthermore, this work advances the traditional binary validation approach (pass/fail) in anti-counterfeiting applications, as this methodology facilitates the harmonized quantification of Raman intensity in relation to marker concentrations in security documents. This improvement enhances traceability and enabling advanced anti-counterfeiting strategies. This study opens a new path for improving the precision and reliability of Raman spectroscopy in fields such as document counterfeiting detection. • Raman interoperability was achieved between two different instruments. • Raman intensity was harmonized with a coincidence of >90 % across different materials. • The method is validated for 785 nm and 532 nm laser excitations. • Chemometrics confirm high reproducibility for high-value document analysis. • This study opens a new path for counterfeit detection using Raman spectroscopy.