Fluopyram is a fungicide which can also be used as a nematicide in agricultural areas. The Brazilian Ministry of Agriculture authorized the commercialization and use of this molecule in Brazilian agriculture in 2019, but studies involving the development of an extraction and quantification method of this compound in environmental matrices such as soil are still scarce. Therefore, the present study aimed to optimize and validate the miniaturized version of the solid-liquid extraction with low temperature purification (SLE-LTP) method for determining this compound in sandy, clayey and medium-textured soil samples. All analyzes in this study were performed by gas chromatography coupled to mass spectrometry (GC-MS). The results revealed that the analyte recovery percentages in the three soil types ranged from 86 to 114% with a relative standard deviation of less than 15%. In addition to employing smaller amounts of reagents and sample, the miniaturized SLE-LTP method was selective, precise, exact, and linear in the range from 3 to 210 μg kg-1, and reached a limit of quantification lower than 3.00 μg kg-1 for the three soil types. The extraction method was applied to 30 real samples collected in coffee growing regions, but no residue of this compound was detected in these samples.

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.

2,4-Dichlorophenoxyacetic acid (2,4-D) has been one of the main herbicides used to control weeds, however, due to its high use it can promote episodes of environmental contamination. Therefore, this study aimed to optimize and validate the liquid-liquid extraction with low-temperature partition (LLE-LTP) and the quick, easy, cheap, effective, rugged, and safe (QuEChERS) methods for determining 2,4-D in water samples by high performance liquid chromatography with diode array detector. The recovery percentages of the two methodologies were close to 100 ± 3%, and the limits of quantification were 2.0 and 3.1 µg L-1 for LLE-LTP and QuEChERS, respectively. The methodologies were selective and presented linearity from 2.0-26.0 and 3.1-40.6 µg L-1 for LLE-LTP and QuEChERS, respectively. The LLE-LTP was better than QuEChERS due to a smaller number of steps, lower reagent consumption, higher concentration factor and a lower limit of quantification. The real samples did not reveal any environmental contamination episodes by 2,4-D.

Polychlorinated dibenzo-p-dioxins and dibenzofurans are persistent organic pollutants which can mainly be found in the environment in water. These compounds are highly toxic and therefore developing new extraction methodologies that are simpler and cost less is highly desirable. This study aimed to optimize and validate the liquid-liquid extraction with low-temperature partition methodology of 2,3,7,8-tetrachlorodibenzo-p-dioxin and 2,3,7,8-tetrachlorodibenzofuran in water samples. The optimum extraction conditions were 8.0 mL of the acetonitrile and 4.0 mL of the water, homogenized in a vortex for 1 min and then maintained at -20 ºC for 1 h. The analytes recovery percentage was close to 100% and relative standard deviation was less than 7%. The methodology was precise, accurate, linear at 2.4-5.4 µg L-1, and selective, with a quantification limit of 2.4 µg L-1. The optimized methodology was applied in ten real samples and the results showed that these analytes were not detected.