Purpose: The aim of this study is to provide data of the spectral characteristics in the THz region of zearalenone (ZEN), a potent oestrogenic mycotoxin, and its derivatives. The potential application of THz time-domain spectroscopy was further investigated by evaluating the detection feasibility.
Methods: The absorption spectra and refractive indices of ZEN and its five derivatives (zearalanone, alpha-zearalenol, alpha-zearalanol, beta-zearalenol and beta-zearalanol) were measured in the range from 0.1 to 2.5 THz using THz time-domain spectroscopy. Computational chemistry using the density functional method was used to study structure and internal rotations in ZEN.
Results: The spectrum of ZEN in the solid phase displayed several absorption peaks over frequency range from 0.1 to 2.5 THz, with significant peaks observed at 1.6, 2.2 and 2.8 THz. Among five derivatives, zearalanone and beta-zearalanol showed specific fingerprints in the frequency range between 0.1 and 2 THz. Theoretical simulation of ZEN shows that the distinct features of the spectrum originated from low-frequency vibrational modes caused by intra-molecular collective motion. The specific absorption peaks of ZEN, zearalanone and beta-zearalanol were still identifiable when mixed with wheat flour, and showed strong intensity in proportion to the concentration (0.1 ~ 10%).
Significance: These results provide the experimental proof-of-concept that THz time-domain spectroscopy could be suitable for screening applications of ZEN and its derivatives in food.