Distributions of imidacloprid, imidacloprid‐olefin and imidacloprid‐urea in green plant tissues and roots of rapeseed ( Brassica napus ) from artificially contaminated potting soil

BACKGROUND Imidacloprid‐urea is the primary imidacloprid soil metabolite, whereas imidacloprid‐olefin is the main plant‐relevant metabolite and is more toxic to insects than imidacloprid. We artificially contaminated potting soil and used quantitative UHPLC‐QqQ‐MS / MS to determine the imidacloprid, imidacloprid‐olefin and imidacloprid‐urea distributions in rapeseed green plant tissues and roots after 4 weeks of exposure. RESULTS In soil, the imidacloprid/imidacloprid‐urea molar ratios decreased similarly after the 250 and 2500 µg kg −1 imidacloprid treatments. The imidacloprid/imidacloprid‐urea molar ratios in the root and soil were similar, whereas in the green plant tissue, imidacloprid‐urea increased more than twofold compared with the root. Although imidacloprid‐olefin was prevalent in the green plant tissues, with imidacloprid/imidacloprid‐olefin molar ratios of 2.24 and 1.47 for the 250 and 2500 µg kg −1 treatments respectively, it was not detected in the root. However, imidacloprid‐olefin was detected in the soil after the 2500 µg kg −1 imidacloprid treatment. CONCLUSION Significant proportions of imidacloprid‐olefin and imidacloprid‐urea in green plant tissues were demonstrated. The greater imidacloprid supply increased the imidacloprid‐olefin/imidacloprid molar ratio in the green plant tissues. The absence of imidacloprid‐olefin in the root excluded its retransport from leaves. The similar imidacloprid/imidacloprid‐urea ratios in the soil and root indicated that the root serves primarily for transporting these substances. © 2016 Society of Chemical Industry