Spectral and chemical characterization of amber from Xixia, Henan Province, China via FTIR, three-dimensional fluorescence spectra and Py (HMDS)-GC-MS

Abstract

Xixia amber from Henan Province in China has undergone a thorough examination utilizing microscopic observation, infrared spectroscopy, and three-dimensional (3D) fluorescence spectroscopy. This systematic analysis has revealed that there are primarily two varieties of Xixia amber: a light-colored type and a dark-colored type. These can be differentiated based on their coloration, infrared spectra, and distinctive fluorescence attributes. Notably, the infrared spectral profile of Xixia amber features a prominent peak at 1023 cm−1, accompanied by less pronounced peaks at 1088 and 974 cm−1. These spectral characteristics set it apart from amber originating from the Baltic regions, Myanmar, and Fushun. Further distinction is achieved through 3D fluorescence spectra, where Xixia amber exhibits similarities to Burmese and Fushun ambers. Chemical classification via pyrolysis gas chromatography-mass spectrometry (Py-GC-MS) identifies Xixia amber as belonging to Class Ib, characterized by its ordered structure and the absence of succinic acid. This comprehensive study delineates the coloration, infrared spectral properties, photoluminescent behavior, and chemical compositions of Xixia amber, clearly differentiating it from ambers sourced from other geographical locations.