Potential of ATR-FTIR Spectroscopy for the Classification of Natural Resins

This study reports evidence on the feasibility of a classification of natural resins by ATR-FTIR spectroscopy based on specific absorbance band positions. A set of twelve selected resins were used to assess band position variability and this vibrational data was put in relationship with the chemical composition of the resins. As a result, a classification of resins into the following four main families is proposed: 1) those correlated with communic acids (sandarac, black copal, pine pitch and amber); 2) those associated with abietic acid (rosin and mastic); 3) those with ketone groups (white copal, tragacanth and frankincense); and 4) those with ester groups (myrrh, shellac and propolis). This classification system may find application not only in facile quality control of natural products, but also for rapid characterization of cultural heritage materials.