Marcia R. Assalin

Studies on degradation of glyphosate by several oxidative chemical processes: Ozonation, photolysis and heterogeneous photocatalysis

Several different Advanced Oxidation Processes (AOPs) including ozonation at pH 6.5 and 10, photolysis and heterogeneous photocatalysis using TiO2 as semiconductor and dissolved oxygen as electron acceptor were applied to study the degradation of glyphosate (N-phosphonomethyl glycine) in water. The degree of glyphosate degradation, the reactions kinetic and the formation of the major metabolite, aminomethyl phosphonic acid (AMPA), were evaluated. Ozonation at pH 10 resulted in the maximum mineralization of glyphosate. It was observed that under the experimental conditions used in this study the degradation of glyphosate followed the first-order kinetics. The half-life obtained for glyphosate degradation in the O3/pH 10 process was 1.8 minutes.

Toxicity Assay in Kraft E1 Effluent Treated by Ozone: Algae Growth Inhibition and Cytotoxicity in V79 Cells

The efficiency of an ozonation process in the degradation of the Kraft E1 effluent was evaluated. The investigation was focused on the reduction of chemical oxygen demand, total phenols, color and the absorbance at 254 nm. The chronic toxicity was evaluated by growth inhibition of algae Selenatrum capricornutum and cytotoxicity evaluation of effluents samples by determination of the nucleic acid content (NCA) endpoint. After 60 minutes of ozonation, COD and UV254 only reached 21% and 34% efficiency reduction. Total phenols and color were more rapidly removed (at 10 minutes of treatment). The results showed that the chronic toxicity (Selenastrum capricornutum algae) decreases for all effluent doses studied. The cytotoxicity assay indicated that toxic compounds were not generated by the ozonation process.

Determination of Moxidectin in Serum by Liquid Chromatography-Tandem Mass Spectrometry and Its Application in Pharmacokinetic Study in Lambs

The widespread use of moxidectin (MOX), a parasiticide used in the sheep breeding, has induced the parasite resistance in Brazilian farms. As a consequence, the farmers often increase the dose and frequency of drug utilization, and disregards safety of meat or milk. In order to establish adequate therapeutic treatment it is necessary to know the pharmacokinetics of the drug in the animals body. Thus, high performance liquid chromatography-electrospray ionization-tandem mass spectrometry (HPLC-ESI-MS/MS) method was developed for the determination of MOX in serum lamb. Serum samples were treated with acetonitrile to precipitate proteins. A clean up by dispersive extraction in solid phase (SPE-d), using primary/secondary amine (PSA) and C18 sorbents, followed by freezing was performed. Method validation presented precision (coefficient of variation) and accuracy (recovery%) between 1.7-6.7 and 80.0-107.3%, respectively. The limit of quantification (LOQ) of the method was 2.0 ng mL-1 and a linear response was obtained over a range of 2.0 to 100 ng mL-1. This method was successfully applied to the determination of MOX in serum from suffolk lamb to evaluate the pharmacokinetic profile.

Multiresidue Method for Quantification of Sulfonamides and Trimethoprim in Tilapia Fillet by Liquid Chromatography Coupled to Quadrupole Time-of-Flight Mass Spectrometry Using QuEChERS for Sample Preparation

A multiresidue method for detecting and quantifying sulfonamides (sulfapyridine, sulfamerazine, sulfathiazole, sulfamethazine, sulfadimethoxine, sulfamethoxazole, and sulfamethoxypyridazine) and trimethoprim in tilapia fillet (Oreochromis niloticus) using liquid chromatography coupled to mass spectrometry was developed and validated. The sample preparation was optimized using the QuEChERS approach. The chromatographic separation was performed using a C18 column and 0.1% formic acid in water and acetonitrile as the mobile phase in the isocratic elution mode. Method validation was performed based on the Commission Decision 2002/657/EC and Brazilian guideline. The validation parameters evaluated were linearity (r ≥ 0.99); limits of detection (LOD) and quantification (LOQ), 1 ng·g−1 and 5 ng·g−1, respectively; intraday and interdays precision (CV lower than 19.4%). The decision limit (CCα 102.6–120.0 ng·g−1 and 70 ng·g−1 for sulfonamides and trimethoprim, respectively) and detection capability (CCβ 111.7–140.1 ng·g−1 and 89.9 ng·g−1 for sulfonamides and trimethoprim, respectively) were determined. Analyses of tilapia fillet samples from fish exposed to sulfamethazine through feed (incurred samples) were conducted in order to evaluate the method. This new method was demonstrated to be fast, sensitive, and suitable for monitoring sulfonamides and trimethoprim in tilapia fillet in health surveillance programs, as well as to be used in pharmacokinetics and residue depletion studies.

Antifungal Activity of Pseudomonas frederiksbergensis CMAA 1323 Isolated from the Antarctic Hair Grass Deschampsia antarctica

Aims: Epiphytic bacteria, isolated from Deschampsia antarctica, were screened for their potential to inhibit the plant pathogen Botrytis cinerea, the causal agent of gray mold disease of strawberry pseudofruits. This phytopathogenic fungus is more active and the disease is more serious in temperate climate where the temperatures are lower. Methodology: The approach involved the isolation and characterization of bacteria from the phyllosphere of D. antarctica and the evaluation of their antifungal activity. Results: A total of 56 bacterial strains were isolated and only one of them, identified by the sequencing of 16S rDNA gene, as Pseudomonas frederiksbergensis CMAA 1323, inhibited the mycelial growth and the conidial germination of the fungus. Its ethyl acetate extract also inhibited Original Research Article Melo et al.; BMRJ, 14(3): 1-11, 2016; Article no.BMRJ.25314 2 the mycelial growth. Analysis of the bioactive fraction by using liquid chromatography coupled to a mass spectrometry (LC-MS) revealed the presence of cyclo(Pro-Val), a compound belonging to the class of diketopiperazines (DKPs). Conclusion: These findings support the potential use of the psychrophilic bacterium P. frederiksbergensis as promising antifungal agent, and highlight the need for more studies with this bacterium in the biological control of plant pathogenic fungi.

Depletion study, withdrawal period calculation and bioaccumulation of sulfamethazine in tilapia (Oreochromis niloticus) treated with medicated feed

The residue depletion of sulfamethazine (SMZ) was evaluated in tilapia (Oreochromis niloticus) after 11 days of administration of medicated feed containing SMZ, at the dose of 422 mg/kg body weight (bw). The determination of SMZ in feed and tilapia fillet was carried out using the QuEChERS approach for sample preparation, and high performance liquid chromatography with diode array detector (HPLC-DAD) and ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QToF-MS) for quantitation, respectively. Both methods were validated based on international and Brazilian guidelines and shown to be suitable for the intended purposes. The withdrawal period to reach the maximum residue level (MRL) of 100 μg/kg, according to the European Union (EU) legislative framework to all substances belonging to the sulfonamide (SA) group (EU, 2010), was 10 days (260 °C-day). After treatment, the maximum level of SMZ accumulation in the tilapia muscle was 1.6 mg/kg. SMZ was shown to be quickly excreted by tilapia. Thus, considering the acceptable daily intake of SMZ established by the Codex Commission (0-0.05 mg/kg bw), and a factor of 5 times the upper amount of fish consumption in Brazil (38 kg/year), this study showed that there is a low risk of adverse effects to consumers. This study offers subsidies not only for the establishment of public policies with regard to the use of veterinary drugs currently not allowed in a country by their legal legislative framework for fish farming, but also to fish producers for the proper handling to ensure safe fish fillets.