Potentiality of Epoxy-Montmorillonite Composite for Stir-Bar Sorptive Extraction for Determination of Atrazine

Abstract A new low-cost material is presented for the first time, aiming to study the sorption process for the stir-bar sorptive extraction (SBSE) technique. The bars were made using a composition of a commercial epoxy resin and montmorillonite, under different compositions and a final ratio of 70% (epoxy) and 30% (montmorillonite) was employed, providing the best mechanical and chemical resistance. A PTFE support was developed to hold the bars permitting the magnetic stirring, without turbulent behavior even under long times of stirring at 1000 rpm. The bars were employed to study the sorption of the herbicide atrazine (ATZ), and the best extraction conditions were: sample volume 20.0 mL, pH 6.0, extraction time of 15 min, room temperature, stirring speed of 100 rpm, and 10.0% (w v-1) NaCl. This preliminary evaluation suggests that the modified bars could be employed for ATZ sorption, affording close to 71% of ATZ removal, and presented robust characteristics to be used at least 80 times.

Intoxicaciones por paraquat reportadas en el Centro Toxicológico de la Región Centro Occidental "Antonio M. Pineda de Venezuela: período 1997-2000 / Paraquat intoxications reported in the Toxicological Center Antonio M. Pineda: from Venezuela 1997-2000

En Venezuela, es frecuente la utilización de plaguicidas como el paraguat en la actividad agrícola, por ello las intoxicaciones y fallecimientos que se producen anualmente por su mal uso, y manejo es importante. Se analizaron retrospectivamente los casos de intoxicaciones por paraquat registrados en el Centro Toxicológico de la Región Centro Occidental de Venezuela, durante los años 1997-2000, para evaluar frecuencia, causas, vías de ingreso y evaluación de los pacientes intoxicados. La investigación fue descriptiva, de registros médicos. Se registraron 79 pacientes; 44 pacientes del género masculino y 29 del género femenino y 6 no identificados en los registros. El promedio de edad fue de 24,22 ± 12,47 años. La principal vía de ingreso del tóxico fue oral 83.5%, y las causas de intoxicación identificadas fueron: 75,9% ocupacional y 22,8% accidental. El 49,3% de los pacientes fue dado de alta., mientras que el 8,8% falleció

In Venezuela, it is frequent the use of pesticides such as paraquat in agriculture, so poisonings and deaths that occur annually for their improper use and handling its important. We retrospectively analyzed the cases of paraquat poisoning recorded in the Poison Center of the Midwestern Region of Venezuela during the years 1997-2000, to assess prevalence, causes, access routes and evolution of poisoned patients. The research was descriptive, of medical records. There were 79 patienrs, 44 males and 29 females and 6 are not identified in the records. The average age was 24.22 ± 12.47 years. The main route of the toxic was oral 83.5%, and the causes of poisoning identified were: occupational 75.9% and accidental 22.8%. The 49.3% of patients were discharged, while 8.8% died

Cellular Toxicity of Surfactants Used as Herbicide Additives

The cellular toxicities of surfactants, a solvent, and an antifreeze that are included in herbicide formulations were assessed by measuring their effects on membrane integrity, metabolic activity, mitochondrial activity, and total protein synthesis rate in a cell culture. Polyethylene glycol, propylene glycol, and monoethylene glycol exhibited no cellular toxicity even at a high concentration of 100 mM. Sodium lauryl ether sulfate and polyoxyethylene lauryl ether significantly damaged the membrane, disturbed cellular metabolic activity, and decreased mitochondrial activity and the protein synthesis rate; however, their toxicity was far below those of the severely toxic chemicals at comparable concentrations. The severely toxic category included polyoxypropylene glycol block copolymer, polyoxyethylene tallow amine, and polyoxyethylene lauryl amine ether. These surfactants were cytotoxic between 3.125 microM and 100 microM in a dose-dependent manner. However, the toxicity graph of concentration vs toxicity had a point of inflection at 25 microM. The slope of the toxicity graph was gentle when the concentration was below 25 microM and steep when the concentration was greater than 25 microM. In conclusion, our results suggest that the toxicity of surfactants be taken care of pertinent treatment of acute herbicide intoxication.

In Vitro Cytotoxic Effect of Glyphosate Mixture Containing Surfactants

We investigated whether glyphosate influences the cellular toxicity of the surfactants TN-20 and LN-10 on the mouse fibroblast-like cells, alveolar epithelial cells, and a heart cell line. The cytotoxicity of TN-20 and LN-10 (0.4-100 microM), in the presence or absence of glyphosate was determined by assessing membrane integrity. TN-20 toxicity was significantly lower in the presence of 50 microM glyphosate for the fibroblast-like cell (6.25 microM; 3.9% +/- 3.4% vs -4.8% +/- 0.7%), for the alveolar cells (0.78 microM; 5.7% +/- 0.9% vs 0.1% +/- 0.6%), and for the heart cell line (25.0 microM; 7.9% +/- 3.0% vs 19.4% +/- 0.7%) compared to that of TN-20 alone. The cellular toxicity of LN-10 towards the fibroblast-like cells was found to be increased in the presence of 50 microM glyphosate when LN-10 concentrations of 50 microM (31.3% +/- 3.9% vs 19.2% +/- 0.9%) and 100 microM (62.1% +/- 3.4% vs 39.0% +/- 0.7%) were compared to that of LN-10 alone. These results suggest that the mixture toxicity may be a factor in glyphosate-surfactant toxicity in patients with acute glyphosate herbicide intoxication.

Quantitative structure-activity relationship of some pesticides.

Herbicides (benzodiazepinediones), insecticides (dioxatricyclododecenes) and larvicides (N-oxalyl derivatives of tebufenozide) have been quantitatively investigated to explore the relationship between the molecular structure and their biological activity using molecular operating environment (MOE) software. The study provides good predictive models, cross-validated by leave-out-one method (Loo). The positive contribution of the descriptor n-O (count of oxygen atom) suggests the additional oxygen atom substitution at R1 position, in addition to benzodiazepine moiety is favorable for herbicidal activity, whereas the negative contribution of y component of dipole moment (Dip(y)) indicates that electronic interactions are also crucial for the activity. The negative correlation of V(SA)2 and globularity (Glo) descriptors clearly indicates that the volume, shape, and rigidity of tebufenozide derivatives determine their larvicidal activity. The biparametric model for insecticides shows that the indicator variable l(CH-CH3) and R(PC) (negative partial charge) are detrimental for its activity. Most of the active compounds in the series have shown less value for these descriptors. The derived QSAR models also provide valuable insights to optimize their toxicity, which remains a major concern for environment safety.

Potential application of urea-derived herbicides as cytokinins in plant tissue culture.

Various urea-derived herbicides and different cytokinin analogues were used to determine their effects on callusing response and shoot regenerating capacity of alfalfa (Medicago sativa L.) and Coleus (Coleus forskohlii Briq.). The herbicides monuron and diuron evoked profuse callusing response from Coleus leaf segments and alfalfa petiole explants on Murashige and Skoog medium. Shoot regeneration by monuron (2.0 mg/l) showed a maximum of 3 multiple shoots both in alfalfa and Coleus with a frequency of 92% and 75%, respectively. Whereas diuron (0.5 mg/l) showed a high frequency of shoot regeneration (89%)with a mean number of 5 shoots in alfalfa, in C.forskohlii, the frequency of regeneration was 90%with a mean number of 6 shoots. Diuron with two chloride groups in the phenyl ring showed significantly higher cytokinin-like activity than single chloride substitution monuron. This study demonstrates the potential use of monuron and diuron as cytokinins in plant tissue culture.

Ion-pair solid-phase extraction (SPE) and HPLC analysis of paraquat in biological sample / 法医学杂志

OBJECTIVE@#To establish an HPLC method for the determination of Paraquat in biological samples.@*METHODS@#Paraquat in biological samples was extracted by C18 columns which were pre-treated with cetyl-trimethyl ammonium bromide (CTAB) and soudium dodecyl sulphate (SDS), and analysed by HPLC/DAD.@*RESULTS@#The detection limit of the method was 1 ng x mL(-1), and the average recoveries were 81%-94%.@*CONCLUSION@#The method can be used to analysis of paraquat in biological samples.