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1.
Regul Toxicol Pharmacol ; 108: 104471, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31493441

RESUMO

Multi-locational supervised field trials were conducted in different agro-climatic regions in India to study dissipation of trifloxystrobin and tebuconazole in tomato after spraying a combination formulation (trifloxystrobin 25% + tebuconazole 50%, 75WG) at recommended doses: (i) single (trifloxystrobin 87.5 g a.i. ha-1 + tebuconazole 175 g a.i. ha-1) and (ii) double (trifloxystrobin 175 g a.i. ha-1 + tebuconazole 350 g a.i. ha-1). Fruit samples were extracted with ethyl acetate using a modified QuEChERS method. The residues (parent fungicides + metabolite) were analyzed and confirmed by GC-ECD and GC-MS, respectively. The half-life (t1/2) of trifloxystrobin and tebuconazole in tomato varied from 1.08 to 1.72 and 1.13 -to 1.64 days at single; and 1.27 to 2.13 and 1.24 to 1.96 days at double dose, respectively. Since maximum residue limit (MRL) at pre-harvest interval (PHI) of 5 days is impractical, as tomato is usually harvested and consumed almost everyday after the last spray, the risk assessment was performed at minimum PHI of 1 day. Accordingly, on the basis of supervised field trial data and using OECD MRL calculator, MRL of 0.5 and 1.5 mg kg-1 at single dose were proposed for trifloxystrobin and tebuconazole in/on tomato, respectively.


Assuntos
Acetatos/análise , Frutas/química , Fungicidas Industriais/análise , Iminas/análise , Resíduos de Praguicidas/análise , Solanum lycopersicum , Estrobilurinas/análise , Triazóis/análise , Adulto , Criança , Exposição Dietética , Cromatografia Gasosa-Espectrometria de Massas , Meia-Vida , Humanos , Nível de Efeito Adverso não Observado , Medição de Risco
2.
J Nanosci Nanotechnol ; 16(1): 643-7, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-27398501

RESUMO

Nanohexaconazole is a highly efficient fungicide against Rhizoctonia solani. Nanoparticles are alleged to adversely affect the non-target organisms. In order to evaluate such concern, the present study was carried out to investigate the effect of nanohexaconazole and its commercial formulation on sensitive nitrogen fixing blue green algae (BGA) and bacteria. Various activities of algae and bacteria namely growth, N-fixation, N-assimilation, Indole acetic acid (IAA) production and phosphate solubilization were differently affected in the presence of hexaconazole. Although, there was stimulatory to slightly inhibitory effect on the growth measurable parameters of the organisms studied at the recommended dose of nanohexaconazole, but its higher dose was inhibitory to all these microorganisms. On the other hand, the recommended as well as higher dose of commercial hexaconazole showed much severe inhibition of growth and metabolic activity of these organisms as compared to the nano preparation. The uses of nanohexazconazole instead of hexaconazole as a fungicide will not only help to control various fungal pathogens but also sustain the growth and activity of these beneficial microorganisms for sustaining soil fertility and productivity.


Assuntos
Antifúngicos/farmacologia , Cianobactérias/metabolismo , Ácidos Indolacéticos/metabolismo , Nanopartículas , Fixação de Nitrogênio/efeitos dos fármacos , Triazóis/farmacologia , Antifúngicos/química , Triazóis/química
3.
J Nanosci Nanotechnol ; 15(2): 1350-6, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26353654

RESUMO

The study was aimed to develop a nano form of an existing fungicide for improving plant protection and reducing crop losses caused by fungal pathogens. The protocol for the preparation and estimation of nanohexaconazole was developed. Technically pure hexaconazole was converted into its nanoform using polyethyleneglycol-400 (PEG) as the surface stabilizing agent. Nanohexaconazole was characterized using Scanning Electron Microscopy (SEM) and Dynamic Light Scattering (DLS) studies. The average particle size of nanohexaconazole was about 100 nm. An analytical method was also developed for quality control of the nanofungicide by GLC fitted with flame ionization detector. Its limit of detection was 2.5 ppm. Fungicidal potential of nanohexaconazole was better in comparison to that of conventional hexaconazole. Hydrolytic and thermal stability studies confirmed its stability at par with the conventional formulation of fungicide. Impact of nanohexaconazole on soil nitrifiers was tested in vitro and there were no significant adverse effect in their numbers observed as compared to conventional registered formulation, proving the safety of the nanofungicide.


Assuntos
Composição de Medicamentos/normas , Nanopartículas/administração & dosagem , Nitrobacter/efeitos dos fármacos , Nitrosomonas/efeitos dos fármacos , Triazóis/administração & dosagem , Triazóis/síntese química , Sobrevivência Celular/efeitos dos fármacos , Fungicidas Industriais/administração & dosagem , Fungicidas Industriais/síntese química , Fungicidas Industriais/toxicidade , Índia , Teste de Materiais , Nanopartículas/química , Nanopartículas/toxicidade , Nitrificação/fisiologia , Nitrobacter/fisiologia , Nitrosomonas/fisiologia , Tamanho da Partícula , Controle de Qualidade , Microbiologia do Solo , Triazóis/toxicidade
4.
Environ Monit Assess ; 187(8): 541, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-26223218

RESUMO

A study was undertaken to evaluate the decline of the residues of pyridalyl in tomatoes grown in two different cultivation systems: open field (conventional cultivation) and net house (pot experiment). Field experiment was conducted with commercial (10 EC) and nanoformulation of pyridalyl on tomato crop. Tomato plants were subjected to pesticide spray, when fruits were close to ripeness. Fruit samples were taken periodically and cleaned up using QuEChERS methodology, and the residue of pyridalyl was analyzed by ultrahigh-performance liquid chromatography (UHPLC). It dissipated in tomato fruit following the first-order kinetics. In field, average initial deposit of pyridalyl in tomato was observed to be 0.222 and 0.371 µg g(-1) at recommended and double the recommended application rate, respectively, using nanoformulation while it was 0.223 and 0.393 µg g(-1) on using commercial formulation, respectively. The half-life (t1/2) value of nanopyridalyl in tomato fruit was 2.8 and 3.2 days while for commercial formulation, it was 2.5 and 2.6 days for recommended and double the recommended dose, respectively. In India, maximum residue limit (MRL) on tomato has not been fixed for pyridalyl but its residues were always below European MRLs (5 µg g(-1)) on tomato at both application rates. The results of terminal residue showed that pyridalyl residues were below the available MRL. Low residues in tomatoes suggested that this pesticide is safe to use under the recommended dosage. No statistical differences were observed between the cultivation systems in relation to the residue levels of pyridalyl.


Assuntos
Monitoramento Ambiental/métodos , Resíduos de Praguicidas/análise , Éteres Fenílicos/análise , Solanum lycopersicum/química , Cromatografia Líquida de Alta Pressão , Monitoramento Ambiental/estatística & dados numéricos , Frutas/química , Meia-Vida , Índia , Cinética
5.
Environ Monit Assess ; 187(3): 123, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25694033

RESUMO

A comparative study on residues and rate of dissipation of a new nanoformulation of pyridalyl and commercial pyridalyl was carried out on okra under net house and field conditions. Okra crop was sprayed with commercial and nanoformulation of pyridalyl at recommended (75 g a. i./ha) and double the recommended dose (150 g a. i./ha) at the time of fruiting. Quantitation of residues of pyridalyl in okra was done by ultra high performance liquid chromatography over a period of 15 days, and recovery of the method ranged from 79 to 87 %. The half life calculated from the dissipation pattern of pyridalyl on okra for commercial and developed nanoformulation proved that residues of nanopyridalyl did not persist much longer than that of conventional formulation in net house as well as in field trials. The risk quotient value of pyridalyl in okra was significantly lower than 1, implying its negligible risk to the humans.


Assuntos
Abelmoschus/química , Nanoestruturas/análise , Resíduos de Praguicidas/análise , Éteres Fenílicos/análise , Monitoramento Ambiental , Frutas/química , Meia-Vida , Inseticidas/análise
6.
J Sep Sci ; 37(9-10): 1126-33, 2014 May.
Artigo em Inglês | MEDLINE | ID: mdl-24677737

RESUMO

In order to identify the most suitable method for the estimation of nanosulfur for studying its residue dynamics, the present work was taken up. HPLC and GC methods were explored for its analysis. A comparative study of the existing analytical methods for the quality control of nanosulfur was undertaken. UV spectrophotometry and HPLC methods were superior with lower LOD when compared to GC-MS, which was not satisfactory due to breakage of catenated S20 into S6 and S8 . The method has been validated by analyzing various nanosulfur formulations of known concentrations. The recovery of the UV and HPLC methods ranged from 80.71 to 109.51% and 82.31 to 109.84%, respectively. The LOD of UV, GC-MS, and HPLC is 4, 20, and 1 ppm, respectively. The retention time of sulfur was 13.77 (HPLC), 2.89 (ultra high performance liquid chromatography), and 12.715 + 21.524 min (GC-MS). The method was successfully utilized for estimating sulfur in natural samples such as water from a sulfur hot spring and wastewater. The method has been validated by following the method recommended by the American Society for Testing and Materials. The HPLC method emerged as the best analytical method for the estimation of elemental sulfur.


Assuntos
Nanoestruturas/análise , Nascentes Naturais/química , Enxofre/análise , Cromatografia Gasosa , Cromatografia Líquida de Alta Pressão , Espectrofotometria Ultravioleta
7.
Curr Microbiol ; 69(2): 183-91, 2014 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-24682261

RESUMO

Bacteria capable of degrading the sulfonated azo dye Red HE7B were isolated from textile mill effluent contaminated soil. The most efficient isolate was identified as Bacillus sp. Azo1 and the isolate could successfully decolorize up to 89% of the dye. The decolorized cultural extract analyzed by HPLC confirmed degradation. Enzymatic analysis showed twofold and fourfold increase in the activity of azoreductase and laccase enzymes, respectively, indicating involvement of both reductive and oxidative enzymes in biodegradation of Red HE7B. Degraded products which were identified by GC/MS analysis included various metabolites like 8-nitroso 1-naphthol, 2-diazonium naphthalene. Mono azo dye intermediate was initially generated from the parent molecule. This mono azo dye was further degraded by the organism, into additional products, depending on the site of cleavage of R-N=N-R molecule. Based on the degradation products identified, three different pathways have been proposed. The mechanism of degradation in two of these pathways is different from that of the previously reported pathway for azo dye degradation. This is the first report of a microbial isolate following multiple pathways for azo dye degradation. Azo dye Red HE7B was observed to be phytotoxic, leading to decrease in root development, shoot length and seedling fresh weight. However, after biotreatment the resulting degradation products were non-phytotoxic.


Assuntos
Compostos Azo/metabolismo , Bacillus/metabolismo , Redes e Vias Metabólicas , Poluentes do Solo/metabolismo , Bacillus/isolamento & purificação , Biotransformação , Cromatografia Gasosa-Espectrometria de Massas , Dados de Sequência Molecular , Análise de Sequência de DNA
8.
J Environ Sci Health B ; 47(4): 326-35, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22428894

RESUMO

Crop losses due to bacterial pathogens are a major global concern. Most of the available pesticides for these pathogens suffer from various drawbacks such as complicated synthesis, high cost, high toxicity, pesticide resistance and environmental hazards. To overcome these drawbacks, the present study was undertaken to find a potent bactericide. Therefore, a series of compounds comprising bioactive furyl and oxazolone rings was synthesized under microwave irradiation and screened for in vitro antibacterial activity. The reactions were completed in fewer than 2 minutes with minimal use of solvents and resulted in high yields. These compounds were screened for antibacterial activity against plant pathogens, Xanthomonas oryzae, Ralstonia solanacearum and nitrifying bacteria, Nitrosomonas species under laboratory conditions. Five compounds were active as antibacterial agents against Xanthomonas oryzae and Ralstonia solanacearum. However, all compounds were effective against the Nitrosomonas species and the best one was 2-furyl-4-(3-methoxy-4-hydroxybenzylidene)-5(4H)-oxazolone. The study revealed the fast and environmentally friendly synthesis of bioactive title compounds, which also hold promise to be used as prototypes for the discovery of potent analogues.


Assuntos
Antibacterianos/síntese química , Antibacterianos/farmacologia , Bactérias/efeitos dos fármacos , Oxazolona/síntese química , Oxazolona/farmacologia , Doenças das Plantas/microbiologia , Antibacterianos/química , Bactérias/crescimento & desenvolvimento , Bactérias/metabolismo , Testes de Sensibilidade Microbiana , Nitrificação , Oxazolona/química
9.
Bull Environ Contam Toxicol ; 89(5): 1027-31, 2012 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-23052637

RESUMO

Thiacloprid is a systemic neonicotinoid. The study hypothesized that difference may be seen in the rate of dissipation of thiacloprid when applied on non-transgenic and transgenic cabbage. Thiacloprid was estimated by HPLC. Half life of thiacloprid in transgenic as well as in normal cabbage ranged between 12.3-13.1 days in two doses of application. Under field condition, after 15 days, 59.2% and 54.3% dissipation was recorded at lower and higher rates of application in transgenic cabbage, where as the insecticide dissipated 57.5% and 59.1% for single dose and double dose application, respectively in non-transgenic cabbage. The study establishes that there is no significant difference in dissipation of a systemic pesticide in transgenic versus non-transgenic cabbage. Decontamination of thiacloprid contaminated cabbage was carried out by different chemical treatments. The application of 0.5% NaHCO(3) (an edible alkali) may be recommended for decontamination. Thiacloprid residues in the day-3 field samples of cabbage could be reduced below Japanese MRL (1.0 mg kg(-1)) by treating with 0.5% NaHCO(3) solution for 1 h.


Assuntos
Brassica/química , Inseticidas/análise , Plantas Geneticamente Modificadas/química , Piridinas/análise , Tiazinas/análise , Toxinas de Bacillus thuringiensis , Proteínas de Bactérias/genética , Brassica/genética , Brassica/metabolismo , Endotoxinas/genética , Proteínas Hemolisinas/genética , Inseticidas/metabolismo , Cinética , Neonicotinoides , Plantas Geneticamente Modificadas/metabolismo , Piridinas/metabolismo , Tiazinas/metabolismo
10.
J Ind Microbiol Biotechnol ; 38(4): 503-11, 2011 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-20686914

RESUMO

An alkalotolerant Pseudomonas strain was enriched and isolated from effluent of the pulp and paper industry. This strain was able to degrade dibenzofuran and utilize it as a sole source of energy and carbon. The GC-MS based detection of various intermediary metabolites of biodegradation suggested the involvement of angular as well as lateral pathway of dibenzofuran biodegradation. The GC-MS based detection of various intermediary metabolites of biodegradation suggested the involvement of angular as well as lateral pathway of dibenzofuran biodegradation. This diverse dioxygenation property of the strain allowed it to utilize various recalcitrant chlorinated xenobiotics and PAHs compounds. This strain showed optimum utilization (~85%) of dibenzofuran (200 mg l⁻¹) within 36 h at pH 10 at 40 °C. The growth of the strain was supported by a wide range of environmental conditions such as temperature, pH, and concentration of dibenzofuran, suggesting that it can be used for in situ bioremediation of dioxin-like compound.


Assuntos
Benzofuranos/metabolismo , Pseudomonas/metabolismo , Biodegradação Ambiental , Dioxinas/metabolismo , Cromatografia Gasosa-Espectrometria de Massas , Concentração de Íons de Hidrogênio , Pseudomonas/crescimento & desenvolvimento , Pseudomonas/isolamento & purificação
11.
Pest Manag Sci ; 65(2): 210-5, 2009 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-19089852

RESUMO

BACKGROUND: Thiacloprid [(Z)-3-(6-chloro-3-pyridylmethyl)-1,3-thiazolidin-2-ylidenecyanamide; Calypso] is a systemic insecticide having persistence in the plant system. It was chosen for the management of the eggplant shoot and fruit borer, Leucinodes orbonalis Guen. Management of this insect pest is difficult because it harbours inside the shoot and fruit portions of eggplant. The persistence of thiacloprid on eggplant has not been studied in India. The Food and Agriculture Organisation (FAO) has proposed its maximum residue limit (MRL) on eggplant as 0.7 mg kg(-1), and there is a need to validate this value. Since residues were found to be above this level, five different decontamination agents were tested for the decontamination of thiacloprid from eggplant. RESULTS: The half-life of thiacloprid was 11.1 and 11.6 days from trials in 2 years. Safety factors such as theoretical maximum daily intake (TMDI) and maximum permissible intake (MPI) were used to arrive at a risk assessment to human health from the analytical data obtained from the field trials. Thiacloprid at the doses tested (30 and 60 g AI ha(-1)) was not effective in managing eggplant fruit borer. A waiting period of 3 days before harvest of the fruits after insecticide application and a processing factor (PF) could not ensure a sufficient margin of safety (MOS). Subjecting the data to a processing factor of 60% could not bring the residues below the proposed MRL. CONCLUSION: Thiacloprid is not found to be an appropriate and effective agent for application to eggplant. Either the proposed MRL needs to be revised or good agricultural practice involving thiacloprid for plant protection in eggplant cultivation is required.


Assuntos
Descontaminação , Resíduos de Praguicidas/química , Piridinas/química , Solanum melongena/química , Tiazinas/química , Animais , Insetos/efeitos dos fármacos , Inseticidas/farmacologia , Cinética , Neonicotinoides , Piridinas/farmacologia , Tiazinas/farmacologia
12.
J Environ Sci Health B ; 44(3): 292-301, 2009 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-19280483

RESUMO

Indoxacarb was applied at 75 and 150 g a.i. ha(-1) for two years to an eggplant (Solanum melongena L.) crop grown in the field plots in order to evaluate its efficacy for management of the lepidopteron pest, shoot and fruit borer. The residues of the insecticide were quantified by high-pressure liquid chromatography (HPLC). The mean initial deposits of indoxacarb on eggplant fruits were found to be 2.60-2.634 mg kg(-1) and 3.64-3.68 mg kg(-1) from the two rates of applications, respectively. They declined with time and reached to non-detectable (< 0.02 mg kg(-1)) after 15-20 d. Residues dissipated with a half-life of 3.0-3.8 d from both first and second-year application. A 3 d waiting period for harvest of fruits after insecticide application and processing resulted in the residue levels that were below the Codex maximum residue limit (MRL) of 0.5 mg kg(-1) thereby achieving a maximum safety and minimum risk to consumers. The best combination of chemicals for decontamination of indoxacarb was found to be by washing with a mixture of alkali and potassium permanganate (KMnO(4)) thereby resulting in the removal of 67.5% and 59.2 % residues for 5 and 10 microg g(-1) spiking doses, respectively. Major products formed on reaction of indoxacarb with alkali were identified by electron spray ionization chromatography/mass spectrometry (ESI/MS). The per cent reduction on the weight and number basis of treated eggplant plots were compared to those observed in control plots to demonstrate the effectiveness of indoxacarb treatment on shoot and fruit borer population.


Assuntos
Mariposas/efeitos dos fármacos , Oxazinas/química , Oxazinas/farmacologia , Solanum melongena/parasitologia , Animais , Monitoramento Ambiental , Análise de Alimentos , Contaminação de Alimentos , Frutas/química , Inseticidas/química , Inseticidas/farmacologia , Larva/efeitos dos fármacos , Estrutura Molecular , Resíduos de Praguicidas/análise , Solanum melongena/metabolismo
13.
Artigo em Inglês | MEDLINE | ID: mdl-29279005

RESUMO

Multi-location supervised field trials were conducted in India at four locations of the All India Network Project (AINP) on Pesticide Residues to study the persistence, dissipation and risk assessment of flubendiamide and deltamethrin on cucumber (Cucumis sativus). Residues of flubendiamide and deltamethrin on cucumber resulting from three spray applications of a combination formulation (flubendiamide 90% + deltamethrin 60%, 150 SC) at recommended (22.5 + 15 g a.i./ha) and double the recommended (45 + 30 g a.i./ha) dose were analysed. On the basis of persistence and dissipation studies, the half- life (T1/2) of flubendiamide on cucumber varied from 1.40 to 2.98 (recommended dose) and 1.55 to 2.76 days (double the recommended dose), while that of deltamethrin ranged from 2.5 to 4.9 (recommended dose) and 2.7 to 3.9 days (double the recommended dose) at the four locations. On the basis of supervised field trial data and using OECD calculator, MRLs in the combination product of 3 mg kg-1 for flubendiamide and 1.5 mg kg-1 for deltamethrin has been proposed for consideration by the Food Safety and Standards Authority of India (FSSAI). Codex, EU and EPA have fixed MRL of 0.2 mg kg-1 for flubendiamide and deltamethrin.


Assuntos
Benzamidas/análise , Cucumis sativus/química , Contaminação de Alimentos/análise , Nitrilas/análise , Resíduos de Praguicidas/análise , Piretrinas/análise , Sulfonas/análise , Agricultura , Cromatografia Líquida de Alta Pressão , Análise de Alimentos , Humanos , Índia , Espectrometria de Massas , Estrutura Molecular , Medição de Risco
14.
Int J Biol Macromol ; 97: 616-624, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-28034824

RESUMO

Accelerated use of pesticides in cutting edge agriculture prompted us to explore smart nanoformulations to subside the consumption of these perilous chemicals. Polymer nanocapsules carrying a fungicide, hexaconazole were developed through ionotropic gelation method utilizing chitosan and tripolyphosphate (TPP). The nanocapsules were characterized by photon correlation spectroscope (PCS), transmission electron microscope (TEM), and Fourier transform infra-red (FTIR) spectroscope. Nanocapsules were optimized for size and high encapsulation efficiency using central composite design (CCD) software. The encapsulation efficiency of nanocapsules for hexaconazole was 73% as assessed by gas chromatography (GC). Nanocapsules were analysed and compared with commercial formulation for controlled release in vitro at three different pH values. Release of hexaconazole from nanocapsules was fastest at pH 4 in comparison to pH 7 and pH 10. Release study in soil was also conducted and revealed a controlled pattern for nanoformulation. The fungicidal activity of the prepared nanoformulation was evaluated against R. solani and was compared with commercial formulation of hexaconazole. The cytotoxicity assay performed on vero cell lines by MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide) assay confirmed that nanoformulation is less toxic than commercial formulation of pesticide.


Assuntos
Quitosana/química , Portadores de Fármacos/química , Nanocápsulas/química , Triazóis/química , Animais , Chlorocebus aethiops , Preparações de Ação Retardada , Portadores de Fármacos/toxicidade , Nanocápsulas/toxicidade , Células Vero
15.
Int J Biol Macromol ; 81: 631-7, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26321424

RESUMO

Smart formulations based on nanomaterials have the capability to reduce the consumption of hazardous pesticides and their impact on human health and environment. Nanoformulations of agrochemicals have the potential to improve food productivity without compromising with the ecosystem. In the present work, controlled release nanocapsules containing acetamiprid were prepared by polyelectrolyte complexation of two natural macromolecules, i.e. alginate and chitosan. The size, morphology and chemical interaction studies of the prepared nanocapsules were investigated by Dynamic Light Scattering (DLS), Transmission Electron Microscopy (TEM), and Fourier Transform Infrared Spectroscopy (FTIR). The zetapotential studies revealed stability of the nanocapsules. TEM results show spherical morphology of the nanocapsules. The encapsulation efficiency was found to be 62% as quantified by Ultra High Pressure Liquid Chromatography (UHPLC). Nanocapsules were analysed for controlled release in vitro at three different pH. Maximum release was observed at pH 10 followed by pH 7 and 4, respectively. A non-Fickian release mechanism was found to be followed by the nanoformulation. A controlled release pattern was also found from nanoformulation as compared to commercial formulation in soil. Thus this formulation can reduce the frequency of application of pesticides by controlling the release and will subsequently reduce their side effects.


Assuntos
Alginatos/química , Quitosana/química , Preparações de Ação Retardada , Nanocápsulas/química , Piridinas/administração & dosagem , Química Farmacêutica , Ácido Glucurônico/química , Ácidos Hexurônicos/química , Concentração de Íons de Hidrogênio , Nanocápsulas/ultraestrutura , Neonicotinoides , Tamanho da Partícula , Solo/química , Espectroscopia de Infravermelho com Transformada de Fourier
16.
J Agric Food Chem ; 52(5): 1220-3, 2004 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-14995124

RESUMO

Five fungal species, namely, Trichoderma viride strain 5-2, T. viride strain 2211, Aspergillus niger, A. terricola, and Phanerochaete chrysoporium were screened for degradation study of beta-cyfluthrin. Each fungal species was allowed to grow in Czapek dox medium containing beta-cyfluthrin (5 mg/mL) as the major carbon source of the medium. The highest degradation of beta-cyfluthrin was observed by T. viride 5-2 (T(1/2) = 7.07 days), followed by T.viride 2211 (T(1/2) = 10.66 days). The degradation of beta-cyfluthrin followed first-order kinetics with a fast degradation rate during first 7 days of growth of the fungi. In the case of T. viride strain 5-2, five degradation products were isolated after 20 days of growth of the fungi, out of which three products were identified as alpha-cyano-4-fluorobenzyl-3- (2,2-dichlorovinyl)-2,2-dimethyl cyclopropane carboxylate, alpha-cyano-4-fluoro-3-phenoxy benzyl alcohol, and 3(2,2-dichlorovinyl)-2,2-dimethyl cyclopropanoic acid.


Assuntos
Fungos/metabolismo , Inseticidas/metabolismo , Piretrinas/metabolismo , Aspergillus/metabolismo , Aspergillus niger/metabolismo , Biodegradação Ambiental , Nitrilas , Phanerochaete/metabolismo , Trichoderma/metabolismo
17.
J Agric Food Chem ; 52(24): 7370-6, 2004 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-15563221

RESUMO

Effects of seed treatments with chlorpyrifos [5 g of active ingredient (ai) kg(-1) of seed] and quinalphos (6.25 g of ai kg(-1) of seed) and standing crop treatments with chlorpyrifos (800 g of ai ha(-1)) and quinalphos (1000 g of ai ha(-1)) on arginine deamination and mineralizable nitrogen were monitored, in the sandy loam and loamy sand soils of two tropical semiarid fields, for three consecutive crop seasons. The arginine ammonification activity of rhizospheric microbes was inhibited after seed treatment with chlorpyrifos and quinalphos and their principal metabolites, 3,5,6-trichloro-2-pyridinol (TCP) and 3,5,6-trichloro-2-methoxypyridine (TMP) and 2-hydroxyquinoxaline and quinoxaline-2-thiol, respectively. Quinalphos produced transient inhibitions, whereas chlorpyrifos and its metabolites (TCP and TMP) exerted a greater inhibition in both loamy sand and sandy loam soils. Arginine ammonification by nonrhizospheric microbes was stimulated by standing crop treatments with both pesticides. In the loamy sand soil, the parent compounds stimulated rhizospheric N-mineralization, whereas the metabolites were inhibitory. However, nonrhizospheric N-mineralization was inhibited by both chlorpyrifos and quinalphos and stimulated by their metabolites. A higher magnitude of inhibition of arginine deamination in the loamy sand than in the sandy loam soil could be due to greater bioavailability of the pesticides in the former, resulting from lesser sorption of the pesticides due to alkalinity of the soil and its low content of clay and organic carbon. Although both pesticides affected mineralizable nitrogen, seed treatment with quinalphos and standing crop treatment with quinalphos and chlorpyrifos produced the most significant effects. The recommended doses of the pesticides not only efficiently controlled whitegrubs, which increased pod yields, but also left no residues in harvested kernels. They also caused no long-term inhibition of ammonification, which could have been of significant concern during the short crop period in semiarid areas where nitrogen determines plant productivity.


Assuntos
Arginina/metabolismo , Clorpirifos/farmacologia , Inseticidas/farmacologia , Nitrogênio/metabolismo , Compostos Organotiofosforados/farmacologia , Solo/análise , Compostos de Amônio Quaternário/metabolismo , Rizoma/microbiologia , Microbiologia do Solo
18.
Chemosphere ; 53(8): 1023-31, 2003 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-14505725

RESUMO

The dissipation of 14C carbaryl in undisturbed soil cores, and of quinalphos (25EC and 20AF) after seed and soil treatments, was investigated under field use conditions, in a semi-arid groundnut field. Residues were analyzed by TLC and HPLC and additionally by LSC for 14C carbaryl. The harvested seed kernels were also tested for the presence of insecticide residues. The movement of carbaryl was limited to 15 cm depth in the loamy sand of Jaipur and was detected till 120 days (DT50 of 14.93 days) after application. Bound residues and 1-naphthol had a DT50 of 11.45 and 13.68 days, respectively. Irrespective of the three types of soil samples investigated, the principal metabolite formed on seed and soil treatments with quinalphos, was 2-hydroxyquinoxaline. With seed treatment, a thiol metabolite of quinalphos was also detected. Higher yields of groundnut were realized with quinalphos treatments in comparison to those from control. Post-harvest, no pesticide residues were found in seeds.


Assuntos
Arachis/fisiologia , Radioisótopos de Carbono/química , Compostos Organotiofosforados/química , Solo/análise , Cromatografia Líquida de Alta Pressão , Índia , Quinoxalinas/química , Contagem de Cintilação , Sementes/química
19.
Bioresour Technol ; 101(12): 4296-305, 2010 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-20156685

RESUMO

The ability of Emericella nidulans var. lata, Neurospora intermedia and Bacillus sp. to treat distillery spent wash in a three stage bioreactor was investigated. Process parameters were optimized in shake flask cultures with the individual strains before treatment of the effluent in a 15-l bioreactor. Treatment was first carried out by the fungi followed by bacteria. The treated effluent showed significant reduction in color (82%) and COD (93%) after 30 h. Metabolites formed after degradation of complex polymers in distillery effluent were assayed by gas chromatography-mass spectroscopy and included furan, simple acid types and organic compounds. Denaturing gradient gel electrophoresis of 16S rDNA and 18S rDNA sequences amplified from DNA isolated from the reactor communities indicated the presence of other organisms besides those introduced initially. The microbial communities were able to carry out bioremediation of distillery effluent and produce discharge that conforms to safety standards.


Assuntos
Bactérias/metabolismo , Reatores Biológicos/microbiologia , Destilação , Fungos/metabolismo , Eliminação de Resíduos Líquidos/métodos , Purificação da Água/métodos , Bactérias/efeitos dos fármacos , Biodegradação Ambiental/efeitos dos fármacos , Carbono/farmacologia , Cor , Eletroforese em Gel de Ágar , Fungos/efeitos dos fármacos , Cromatografia Gasosa-Espectrometria de Massas , Nitrogênio/farmacologia , Oxigênio/isolamento & purificação
20.
Pest Manag Sci ; 65(7): 817-22, 2009 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-19367562

RESUMO

BACKGROUND: An efficient delivery system for seed-protectant chemicals is needed in light of several disadvantages of conventional seed treatment methods. This study evaluates the efficacy of film-coat application in maintaining the persistence and potency of imidacloprid on Lycopersicon esculentum (L.) Mill. seeds after simultaneous storage under ambient and regulated environment in paper and aluminium packages. RESULTS: High-performance liquid chromatography (HPLC) revealed 0.135 mg kg(-1) of herbage material to be the threshold value beyond which absolute control was obtained, and with film coating the latter was achieved even with half-dosage seed treatment, irrespective of the storage condition. The technique provided early protection to the crop and also nullified the deleterious effects of ambient storage on the persistence and potency of the pesticide. CONCLUSION: Film coating enabled superior pesticide dosage as well as higher biological efficacy to be achieved. Hence, in addition to being an ecofriendly alternative, the technique would be a more economically viable option for storage of treated seeds.


Assuntos
Manipulação de Alimentos , Imidazóis/análise , Inseticidas/análise , Nitrocompostos/análise , Solanum lycopersicum/química , Animais , Estabilidade de Medicamentos , Hemípteros/efeitos dos fármacos , Imidazóis/farmacologia , Inseticidas/farmacologia , Neonicotinoides , Nitrocompostos/farmacologia , Sementes/química
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