Determination of azoxystrobin residues in grapes, musts and wines with a multicommuted flow-through optosensor implemented with photochemically induced fluorescence

In this paper, the conversion of azoxystrobin in a strongly fluorescent degradation product by UV irradiation with quantitative purposes and its fluorimetric determination are reported for the first time. A multicommuted flow injection-solid phase spectroscopy (FI-SPS) system combined with photochemically-induced fluorescence (PIF) is developed for the determination of azoxystrobin in grapes, must and wine. Grape samples were homogenized and extracted with methanol and further cleaned-up by solid-phase extraction on C18 silica gel. Wine samples were solid-phase extracted on C18 sorbent using dichloromethane as eluent. Recoveries of azoxystrobin from spiked grapes (0.5–2.0 mg Kg−1), must (0.5–2.0 μg mL−1) and wine (0.5–2.0 μg mL−1) were 84.0–87.6%, 95.5–105.9% and 88.5–111.2%, respectively. The quantification limit for grapes was 0.021 mg Kg−1, being within European Union regulations, and 18 μg L−1 and 8 μg L−1 for must and wine, respectively.