Determination of the herbicide fluroxypyr in oil matrices

The purpose of this study was to develop a method for the determination of fluroxypyr (4-amino-3,5-dichloro-6-fluro2-pyridyloxyacetic acid) residue in palm oil namely crude palm oil (CPO) and crude palm kernel oil (CPKO). The method involves the extraction of the herbicide from the oil matrix followed by low temperature precipitation and finally quantification of the residues using the high performance liquid chromatography (HPLC). The extraction efficiency of the method was evaluated by conducting recovery studies. The recovery of fluroxypyr from the fortified CPO samples ranged from 78%–111% with the relative values for the coefficient of variation ranging from 1.4 to 8.6%. Furthermore, the recovery of fluroxypyr from the spiked CPKO samples ranged from 91–107% with the relative values for the coefficient of variation ranging from 0.6 to 4.5%. The minimum detection limit of fluroxypyr in CPO and CPKO was 0.05 μg/g. The method was used to determine fluroxypyr residues from the field-treated samples of CPO and CPKO. When fluroxypyr was used for weed control in oil palm plantations no residue was detected in CPO and CPKO irrespective of the sampling interval and the dosage applied at the recommended or double the manufacturer's recommended dosage.     

QuEChERS-based study on residue determination and dissipation of three herbicides in corn fields using HPLC-MS/MS

A rapid, simple, and selective analytical method was developed and validated for the simultaneous determination of florasulam, fluroxypyr, and fluroxypyr-meptyl in corn grain, plant, and soil using the QuEChERS (quick, easy, cheap, effective, rugged, and safe) procedure coupled with high-performance liquid chromatography-tandem mass spectrometry. The method gave mean recoveries in the range of 80%–108%, with limits of quantification ranging from 2 to 10 µg kg^?1. The half-lives of the three compounds were 1.3–1.3, 0.7–1.3, and 0.7–1.3 days in plants, and 1.1–2.1, 0.4–1.3, and 0.4–1.3 days in soil. The terminal residues in all the matrices were found to be less than the limits of quantification at the pre-harvest intervals of 53 and 78 days. These results not only gave insights about the analytes but also contributed to the safe use of the broad-spectrum herbicides and a reference for establishing the maximum residue limit of florasulam in corn in China.