Selective extraction of zearalenone from corn steep liquor for raw material of standard substance using polyamide membrane

Abstract

Zearalenone (ZEN) is one of the most prevalent mycotoxins in corn and its products, which can accumulate in corn steep liquor (CSL) with much higher concentration after deep processing. For ensuring the precision of ZEN analysis in food safety, ZEN standard substance is critical. However, the preparation of standard substance usually needs complex chemical synthesis steps and large amounts of organic solvents consumption. Herein, a facile approach to extract ZEN from CSL for raw material of standard substance using polyamide 66 (PA) membrane as an adsorbent was proposed. Considering the coexistence of aflatoxin B₁ (AFB₁) and ZEN in CSL, the influence of solvent polarity, membrane pore size, and pH on the selective adsorption of ZEN and AFB₁ have been investigated. Under the optimal conditions, the highest adsorption efficiencies of ZEN and AFB₁ were 96.5 % and 15.9 %, respectively. A good regeneration and reusability of ZEN from PA membrane could be realized by a desorption process using acetonitrile as eluent. Through various characterizations and density functional theory calculations, it can be concluded that the selective adsorption of ZEN on the PA membrane was dominated by special hydrogen bond and hydrophobic interaction, while the adsorption of AFB₁ on the PA membrane was only hydrophobic interaction. Furthermore, PA membrane was used in the extraction of ZEN from contaminated CSL, and the extract rate reached 95.6 %. The present work not only provided a reliable way to high-quality utilization of ZEN contaminated CSL, but also casted new insights into the adsorption mechanism of ZEN.