Extraction procedures for the study of phytotoxicity and degradation processes of selected triketones in a water ecosystem

Simple and effective extraction methods based on matrix solid-phase dispersion (MSPD), dispersive liquid-liquid microextraction (DLLME), and solid-phase extraction (SPE) coupled with high-performance liquid chromatography with diode array detector (HPLC-DAD) were developed to determine triketone herbicides-sulcotrione (SUL), mesotrione (MES), tembotrione (TEMB), and their degradation products-in plant tissues and water samples. The extraction procedures were employed to enable quantification of the accumulation of selected triketone herbicides and their degradation products in a model aquatic plant, Egeria densa. To obtain comprehensive information about the triketones' influence on an aquatic plant, changes in chlorophyll concentration in plants exposed to these triketones were monitored. The average recovery ranged from 58 to 115 % (coefficients of variation 7-12 %) for plant tissues and from 52 to 96 % (coefficients of variation 8-20 %) for water samples. The limit of detection (LOD) for the MSPD-HPLC-DAD procedure was in the range of 0.06-0.23 μg/g, whereas for DLLME-HPLC-DAD and SPE-HPLC-DAD, LOD was in the range of 0.06-0.26 μg/mL. Symptoms of the phytotoxicity of sulcotrione, mesotrione, tembotrione, and their degradation products (decrease of chlorophyll concentration in plant sprouts) were observed for E. densa cultivated in water with herbicide concentrations of 100 μg/L. Moreover, the tembotrione degradation product exhibited a high level of accumulation and low metabolism in plant tissues in comparison to the other triketones and their degradation products.