Direct photolysis of fumonisin B1 in aqueous medium

Abstract

Fumonisins (FBs), secondary metabolites produced by fungi of the genus Fusarium [1], represent a major threat as potential organic pollutants. The FBs have been detected in different types of water [2], as well as produced them by fungi in untreated surface water [3]. Advanced Oxidation Processes (AOPs), have a high potential for water purification, including the removal of hazardous substances and pathogens from different types of water. AOPs are based on physicochemical processes that produce mainly hydroxyl radicals (OH), representing primary oxidants, which can lead to complete mineralization of pollutants. These processes can be initiated by UV or solar radiation. The photocatalytic degradation has become a powerful method for degradation and transformation of aflatoxin B1 [4], zearalenone [5], and deoxynivalenol [6] into harmless substances. In this paper, we have investigated optimization of high performance liquid chromatography with fluorescence detector method for monitoring the stability of fumonisins B1 (FB1), B2 (FB2), and B3 (FB3) solutions as well as the efficiency of FB1 degradation using direct photolysis under UV and solar radiation in ultrapure water. It was found that the sensitivity and separation of the FB1 peak from o-phthalialdehyde2-mercaptoethanol (used for derivatization) was optimally at isocratic elution using the MeOHNaH2PO4 mobile phase, at a ratio of 75 : 25 (v/v). When studying the efficiency of direct photolysis of 1.47 × 10–6 mol/dm3 solution of FB1 it was found that after 180 min of irradiation degradation efficiency was 88% using UV and 76% using solar radiation at pH 8.2. Also, the effect of pH in the range from 4.0 to 10.0 on the efficiency of direct photolysis of FB1 was examined.