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.

苄氟氯吡氧乙酸（Florpyrauxifen-benzyl）是巴西法规新近批准的活性成分，作为除草剂可用于水稻田杂草防控，但有关其人体与环境毒性的研究仍处于审核阶段。由于其近期才进入全球农药市场，针对该化合物的提取与检测方法研究仍较为有限。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（High-Performance Liquid Chromatography coupled to Diode Array Detection，HPLC-DAD）法，用于土壤中苄氟氯吡氧乙酸的定量分析。结果表明，最优实验条件为：采用Poroshell色谱柱，柱温30 ℃，流动相为含0.1%（v/v）甲酸酸化的乙腈-水（体积比85:15），流速0.3 mL·min⁻¹，检测波长243 nm。最优萃取相为含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%。该方法具备良好的精密度、准确度、线性度与选择性，定量限为20 μg·kg⁻¹。针对该化合物在土壤中的稳定性研究表明，苄氟氯吡氧乙酸在土壤中的半衰期约为17.5天。