Data-Driven FTIR Spectroscopy for the Discrimination of Nectars

Nectar composition varies across plant species and environments, influencing pollinator interactions and honey quality. Reliable methods for nectar discrimination, however, remain limited. Here, we demonstrate the use of Fourier-transform infrared (FTIR) spectroscopy combined with chemometric analysis to differentiate nectar samples of <i>Echium vulgare</i> (<i>E. vulgare</i>) and <i>Hedera helix</i> (<i>H. helix</i>) collected in urban locations. Among eight tested preprocessing strategies, simple approaches such as Savitzky-Golay smoothing or even raw spectra provided the best clustering results. The most discriminative spectral regions were consistently the carbohydrate fingerprint (1200-950 cm^-1) and the C-H stretching zone (2935-2885 cm^-1). Mean spectra and PCA confirmed that variability between locations arises mainly from carbohydrate-associated bands, while solvent type, biological matrix, and environmental exposure also affect spectral fingerprints. These results highlight FTIR spectroscopy as a rapid, non-destructive, and robust method for nectar discrimination, with potential applications in food authentication, ecological research, and pollinator-plant studies.