Fig. 7From: The use of infrared spectroscopy and chemometrics to investigate deterioration in vegetable tanned leather: potential applications in heritage sciencePlots of distance (Euclidean) between pH 3 and pH 5 trends—the greater the distance, the greater the change in FTIR peak depending on pH. The analysis of 800–1800 cm−1 is shown on the left, with the same important regions included when the full FTIR spectrum is analysed (right). Missing regions are where no change is observed in the FTIR region depending on pH i.e. these peaks are clustered together for both pH 3 and pH 5Back to article page