Fluorimetric determination of thiabendazole residues in mushrooms using sequential injection analysis

Thiabendazole is a benzimidazole fungicide of general use that is specifically used to control mushroom diseases, mainly cobweb diseases, which is caused by members of the genus Cladobotryum. Although this compound is legislated and its maximum residue limit established at 60 mg kg−1 by Codex Alimentarius, there is almost a complete absence of analytical methods available for its determination in mushrooms. Here, we propose an automated method, using Sequential Injection Analysis with fluorescence detection (λexc/λem = 305/345 nm) for the determination of thiabendazole in mushrooms. We have developed a flow-through optosensor using C18 silica gel as solid support placed in the flow-cell where the determination is performed. This method presents a detection limit of 0.5 mg kg−1, and recovery experiments have been carried out in different kinds of mushrooms at levels below the legislated maximum residue limit, demonstrating that the proposed analytical method fulfils the requirements for its applications in quality control of mushrooms.