Optimization and validation of LLE-LTP to determine florpyrauxifen-benzyl herbicide in water samples by HPLC-DAD

Florpyrauxifen-benzyl is a systemic herbicide which acts on weeds of common occurrence in rice cultivation areas using flooded or rainfed systems. The Brazilian Health Regulatory Agency (ANVISA) authorized the commercialization of this pesticide, but did not establish guidelines with an extraction and quantification method of residues of this compound as a form of environmental monitoring. Therefore, the present study aimed to optimize and validate the liquid-liquid extraction with low temperature purification (LLE-LTP) to determine florpyrauxifen-benzyl content in water samples by high performance liquid chromatography with diode array detection (HPLC-DAD). The recovery ranged from 95.84 to 105.4% with a relative standard deviation less than 1.5. LLE-LTP was selective, precise, accurate, linear in the range from 4.00 to 150 µg L^-1, and the limit of quantification was 4.00 µg L^-1. The stability study of the compound in water revealed its degradation in 25 days and DT₅₀ in approximately 5 days. LLE-LTP coupled to HPLC-DAD presented itself as a simple, easy and efficient method of extracting and analyzing it in water samples.