Extraction Method for Determining Florpyrauxifen-benzyl Herbicide in Soil

Florpyrauxifen-benzyl is the new active ingredient authorized by Brazilian legislation, which acts as herbicide and may be used to control weeds in rice cultivation, but studies on toxicity to humans and the environment are still under review. Due to recent insertion in the world pesticide market, there are still few studies related to the extraction and detection methodologies of this compound. Therefore, this study aimed to optimize and validate solid-liquid extraction with low temperature purification (SLE-LTP) for determining florpyrauxifen-benzyl in soil using high-performance liquid chromatography coupled to a diode array detection (HPLC-DAD). The results showed that the best conditions were achieved using Poroshell column, a temperature of 30 °C, mobile phase composition of acetonitrile:water (85:15 v/v) acidified with formic acid 0.1% (v/v), a flow rate of 0.3 mL min-1, and 243 nm as the wavelength. The best extracting phase was acetonitrile acidified with formic acid 0.1% (v/v) which achieved a recovery rate ca. 100% and relative standard deviation (RSD) less than 3.9%. The methodology was precise, accurate, linear and selective, with a limit of quantification of 20 µg kg-1. The stability study of this compound in soil showed that approximately 17.5 days is the half-life of florpyrauxifen-benzyl in soil.

氯氟吡啶酯苄酯（Florpyrauxifen-benzyl）是巴西法规新近批准的农药活性成分，可作为除草剂用于稻田杂草防控，但关于其人体与环境毒性的相关研究仍处于审核阶段。鉴于其近年才进入全球农药市场，目前针对该化合物的提取与检测方法研究仍较为匮乏。为此，本研究旨在优化并验证低温净化固液萃取（solid-liquid extraction with low temperature purification, SLE-LTP）结合高效液相色谱-二极管阵列检测器（high-performance liquid chromatography coupled to diode array detection, HPLC-DAD）的分析方法，用于土壤中氯氟吡啶酯苄酯的定量检测。结果显示，最优分析条件如下：采用Poroshell色谱柱，柱温设置为30℃，流动相为含0.1%（v/v）甲酸酸化的乙腈-水溶液（体积比85:15），流速0.3 mL·min⁻¹，检测波长为243 nm。最优萃取溶剂为含0.1%（v/v）甲酸酸化的乙腈，该条件下加标回收率约为100%，相对标准偏差（relative standard deviation, RSD）小于3.9%。该方法精密度、准确度、线性度与选择性均符合要求，定量限为20 μg·kg⁻¹。土壤中该化合物的稳定性研究表明，氯氟吡啶酯苄酯在土壤中的半衰期约为17.5天。