The validation of an analytical method for sulfentrazone residue determination in soil using liquid chromatography and a comparison of chromatographic sensitivity to millet as a bioindicator species

Rhizosphere-associated microbiota of Canavalia ensiformis in sulfentrazone bioremediation

The objective of this study was to determine the efficiency of the microbial rhizosphere (Canavalia ensiformis) in the phytoremediation of sulfentrazone using quantification methods (CO2 evolution, microbial biomass carbon, and metabolic quotient) and identification of bacteria (PCR-DGGE technique). The experiment was conducted in a completely randomized design, in a 2x4 factorial scheme, with four replications. The treatments were composed of rhizospheric soil (cultivated with C. ensiformis) and non-rhizosphere soil (uncultivated soil); and four levels of contamination by sulfentrazone (0, 200, 400, and 800 g ha-1 a.i.). The microbiota associated with the rhizosphere of C. ensiformis efficiently reduced sulfentrazone residues in the soil, with better performance at the dose of 200 g ha-1 a.i. Using the PCR-DGGE technique allowed the distinction of two profiles of bacteria in the rhizospheric activity of C. ensiformis. The second bacterial profile formed was more efficient in decontaminating soil contaminated with sulfentrazone residue. The microbiota associated with the rhizosphere of C. ensiformis has an efficient profile in decontaminating soils with residues equivalent to 200 g ha-1 a.i. the herbicide sulfentrazone.

Canavalia ensiformis enhances the phytoremediation of remineralized and sulfentrazone-contaminated tropical soils

The objective of the study was to assess the phytoremediation potential in two remineralized soils contaminated with sulfentrazone. Two soil types were evaluated: Oxisol (clayey) and Inceptisol (sandy loam), in pots, with and without the incorporation of the rock powder, at rates of 0, 4, and 8 t ha-1. Following this, sulfentrazone was applied at rates of 200, 400, 600, and 800 g a. i. ha-1, in addition to the control treatment without herbicide application, followed by the sowing of Canavalia ensiformis (jack bean). Injury level (IL) was assessed at 42 days after emergence (DAE), and biometric evaluations of the phytoremediating species were conducted at 70 and 120 DAE in the Oxisol and Inceptisol, respectively, for the following variables: height (HT), diameter (DM), trifoliate leaf number (TN), leaf area (LA), above-ground dry biomass (DB), and root dry biomass (RDB). At the end of the phytoremediation experiment, the soils were analyzed using High-Performance Liquid Chromatography (HPLC) and with Sorghum bicolor (sorghum) as a bioindicator to verify the residue of sulfentrazone. IL and DB assessments of the bioindicator species were conducted at 21 DAE. In both soils, higher herbicide rates (600 and 800 g a. i. ha-1) resulted in greater IL and reduced HT, LA, DB, and RDB of the phytoremediating species. C. ensiformis reduced the sulfentrazone residues in the soils. Although it did not directly influence phytoremediation, the rock powder improved soil fertility. In conclusion, C. ensiformis has the potential for effective phytoremediation of soils contaminated with sulfentrazone, providing safety for cultivating sensitive crops and benefiting the environment.

Does Canavalia ensiformis inoculation with Bradyrhizobium sp. enhance phytoremediation of sulfentrazone-contaminated soil?

Symbiosis among herbicide-metabolising microorganisms and phytoremediation plants may be an efficient alternative to remediate sulfentrazone-contaminated soils. This work evaluated the bioremediation of sulfentrazone-contaminated soils by symbiosis between bacteria (Bradyrhizobium sp.) and jack bean (Canavalia ensiformis L.). The experiment was carried out in a greenhouse between March and May of 2018, in the Universidade Federal do Espírito Santo (UFES). Four doses of sulfentrazone (0, 400, 800, and 1200 g ha^-1 a. i.) were tested with and without inoculation with Bradyrhizobium sp. BR 2003 (SEMIA 6156) After 80 days of cultivation, plants were cut and soil was collected for determination of the herbicide residual levels and millet bioassay. The sulfentrazone concentration was significantly reduced by plant inoculation with Bradyrhizobium sp.: on average, concentrations were 18.97%, 23.82%, and 22.10% lower than in the absence of inoculation at doses of 400, 800, and 1200 g ha^-1, respectively. Symbiosis promoted a reduction of up to 65% in residual soil herbicides. Under the 1200 g ha^-1 dose, inoculation promoted greater plant height than in the uninoculated plant. Regardless of the dose of sulfentrazone, the dry root mass was higher in the inoculated plants. The microbiological indicators showed satisfactory results mainly for the dose of 400 g ha^-1. The results of this study highlight the potential of positive interactions between symbiotic microorganisms and leguminous species, aiming toward the phytoremediation of sulfentrazone herbicide.

Phytoremediation and natural attenuation of sulfentrazone: mineralogy influence of three highly weathered soils

This study evaluated remediation of the herbicide sulfentrazone in soils with three different mineralogies (kaolinite, hematite, and gibbsite) and three remediation sulfentrazone treatments (Canavalia ensiformis L., Crotalaria juncea L., and natural attenuation). This study was conducted in a factorial scheme, in triplicate with randomized block design. Sulfentrazone was applied at 0 and 400 g ha^-1. We analyzed sulfentrazone residue in the soils by high-performance liquid chromatography and confirmed the results with bioassays of Pennisetum glaucum. Herbicide movement was greater in the kaolinitic soil without plant species. The retention of herbicide in the kaolinitic soil occurred in larger quantities in the 0-12 cm layer, with higher levels found in the treatments with plants. In the hematitic soil with C. juncea, all applied herbicides were concentrated in the 0-12 cm layer. In the other hematitic soil treatments, sulfentrazone was not detected by chemical analysis at any soil depth, although in many treatments, it was detected in the bioassay. Phytoremediation was more efficient with C. ensiformis grown in gibbsitic soil, reducing the sulfentrazone load by approximately 27%. Natural attenuation was more efficient than phytoremediation in oxidic soils due to soil pH and texture soils favored microbial degradation of the compound. Highlights The influence of soil mineralogy of herbicide sulfentrazone retention was evaluated. Canavalia ensiformis and Crotalaria juncea were evaluated as phytoremediation plants. Kaolinite soils presented great movement of sulfentrazone in the soil. Natural attenuation is more efficient in oxide soils than phytoremediation.

Calculate of withdrawal times of clenbuterol in goats to obtain safe times of slaughter

Background and Aim:

Clenbuterol as a β₂-agonist drug was investigated according to the concentration of the drug available in the bodies of goats and according to the level of sensitivity of the instruments used for detection. The objective of the current study was to determine withdrawal times after giving a therapeutic dose that resulted in safe slaughters.

Materials and Methods:

Five healthy male goats with a mean body weight of 20.64 kg were treated with a single dose of 5.10⁻³ mg^/kg in the BW onto jugular vein. Whole blood samples of approximately 5 mL were taken in a time series at 5, 30, 60, 90, 150, 210, 270, 390, 510, 630, and 750 min. At 24 h posttreatment, all subjects were sacrificed, and 300 g samples of the liver were obtained. The plasma concentration and liver residue of the drug were observed by reverse-phase high-performance liquid chromatography.

Results:

The drug reached a maximum concentration of 19.233±0.331 µg/mL at 5 min, and the elimination half-life was at 173.25 min. The limit detection was obtained at 0.053 µg/mL. A one-way analysis of variance between all goats showed that elimination of the clenbuterol in their bodies was similar (p=1.00), with a withdrawal time of 1,479.326 min and no residues in the liver (p<0.05).

Conclusion:

Safe times for slaughter were determined to be at 2 days, 13 h, and 12 min as the 2^nd safety factor (SF) time and 3 days, 1 h, and 58 min as the 3^rd SF time with the liver organ free from residue.

elimination half-life, new method for calculating withdrawal time, prescriptions for obtained β₂-agonist, residues in liver.

Near-near-infrared thermal lens spectroscopy to assess overtones and combination bands of sulfentrazone pesticide

Thermal lens spectroscopy (TLS) in the near-near-infrared region was used to explore the absorptions of overtones and combination bands of sulfentrazone (SFZ) herbicide diluted in methanol. This spectroscopic region was chosen in order to guarantee that only thermal lens effect is noted during the experimental procedure. The results showed that it was possible to detect very low concentrations (~2ng/μL) of SFZ in methanol by determining its thermal diffusivity or the absorption coefficient due to the 3ν(NH)+1δ(CH) combination band. This minimum SFZ concentration is the limit observed by chromatography method. The findings demonstrated that the TLS can be used for precise and accurate assessment of pesticides in ecosystems. Besides, the 3ν(NH)+1δ(CH) combination band at 960nm can be used as a marker for SFZ in methanol.