Rapid discrimination of china sponges by Tri-step infrared spectroscopy: A preliminary study

• Nine sponges from two classes and six orders were discriminated by Tri-step IR.
• Sponges of the same genus were definitely discriminated.
• 2DCOS-IR was applied to identify sponges with similar chemical profile distinctly.

Trip-step infrared spectroscopy, Fourier transform infrared spectroscopy combined with second derivative infrared spectroscopy (SD-IR) and two-dimensional correlation infrared spectroscopy (2DCOS-IR), was employed to characterize and discriminate nine China sponges. Sponges from different classes and different orders had respective unique IR macro-fingerprints. Their IR spectra suggested that the prime ingredient of calcareous sponges was calcium carbonate in calcite and/or aragonite forms, but that of demosponges was protein. Particularly, the sponges from the same genus which could not be identified by traditional spicule identification have been definitely discriminated. For sponges having highly similar chemical profile (IR spectral profile), SD-IR and 2DCOS-IR have been applied to enhance the spectral resolution to distinguish the sponges convincingly.