Sensitive Photochemically Induced Fluorescence Sensor for the Determination of Nitenpyram and Pyraclostrobin in Grapes and Wines

The primary aim of this study is to report a new approach for pesticide determination, based on the use of automated luminescent sensors for the analysis of specific analytes. In this regard, we have selected two widely used pesticides—nitenpyram and pyraclostrobin—as target compounds. The proposed system makes use of multicommutated flow injection analysis by employing photochemically induced fluorescence as detection technique. Strong fluorescent photodegradation products were obtained on-line by UV-irradiation of the analytes. Then, the on-line separation and pre-concentration of the analytes were carried out on the surface of C18 silica gel beads placed inside the flow cell, where the analytical signal was recorded. The proposed analytical method presents a detection limit of 0.2 mg kg−1 for both analytes. After an appropriate sample treatment, the method complies with the current maximum residue limits in table grapes and wine grapes. We carried out recovery experiments in grapes and wines, obtaining recoveries between 96 and 107% in all cases. The simplicity, low-cost, and high sensitivity of the proposed method make it an attractive approach for the analysis of these two pesticides in food commodities.