In vivo tracing of triazole pesticides in Chinese cabbage via a novel solid-phase microextraction fiber

In this study, a nitrogen-rich triazine-based porous polymer (NTP) was prepared by the Schiff base mechanism. The NTP contains a high nitrogen content (35.47%) with a larger BET surface area and an adsorption average pore diameter of 860 m(2) g(-1) and 3.92 nm, respectively. In addition, secondary amines (-C-NH-) and triazine nitrogen (-C=N-) in NTP provide a large number of nitrogen active sites, which facilitate the adsorption of triazole pesticides. The synthesized NTP was then used as the solid phase microextraction (SPME) extraction phase material to fabricate the NTP-SPME fiber, which had significantly higher performance in extracting tri-azole fungicides compared to the commercial fibers (p < 0.05). Subsequently, the bioaccumulation and elimination of three triazole fungicides (myclobutanil, propiconazole, and difenoconazole) in living vegetables were tracked by in vivo SPME sampling and quantified using a gas chromatography quadrupole time-of-flight mass spectrometry. The results showed that the concentrations of myclobutanil, propiconazole and difenoconazole were highest on the first day and showed a trend of first decreasing then equilibrium during bioaccumulation and gradually decreasing during elimination. The highest concentrations of myclobutanil, propiconazole, and difenoconazole in cabbage stems were 997.57 +/- 51.42, 841.20 +/- 21.42, and 56.82 +/- 1.30 ng/g, respectively. In addition, concentrations of difenoconazole were much lower than those of other pesticides throughout the experimental period, which may be related to the difficulty of uptake by cabbage roots due to its strong hydrophobicity and low solubility. This study highlights the application of NTP-SPME for tracking triazole fungicides in living Chinese cabbage plants, which provides valuable information to rationale use of triazole fungicides and their ecological risk assessment.