Madhuban Gopal

Chromatographic techniques in the analysis of organochlorine pesticide residues.

The review briefly covers the chromatographic techniques used in the analysis of organochlorine pesticide residues. The organochlorines ranging from DDT, HCH, the cyclodiene group and the polychloroterpene group have been covered. It endeavours to examine the existing methodologies and techniques including residue extraction, clean-up, chromatographic procedures involved in clean-up and determination and quantification of organochlorine residues by gas liquid chromatography from different substrates like food commodities, crops, soil and water.

Environmental behaviour and translocation of imidacloprid in eggplant, cabbage and mustard

The recently registered insecticide, imidacloprid, was applied to three vegetable crops at 20 and 40 g AI ha−1. The persistence of the parent insecticide and its translocation, along with the quantification of the metabolites formed on these crops are presented. The parent insecticide dissipated with a half-life of 3–5 days and persisted longest on mustard leaves. The detectable limit of the HPLC method was 0.01 µg g−1. The metabolites 1-(6-chloropyridin-3-yl-methyl)imidazolidin-2-one and 6-chloronicotinic acid were found to be translocated by day 10 in eggplant, cabbage leaves and mustard leaves but not in cabbage curd. The MRL of imidacloprid is not documented by the FAO/WHO on these crops and comparison of the MPI with the TMRC, calculated on the residue data generated in this study, establishes the safety of the schedule. © 2000 Society of Chemical Industry

Biodegradation of beta-cyfluthrin by Pseudomonas stutzeri strain S1.

Abstractβ-Cyfluthrin [α-cyano-4-fluoro-3-phenoxybenzyl-3(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylate] pesticide has been in agricultural use in the recent years for controlling Lepidopteran pests affecting solanaceous crops. The extensive use of synthetic pyrethroids like β-cyfluthrin has resulted in wide spread environmental contamination. The purpose of this study was to isolate bacteria from soil and to determine their ability to degrade β-cyfluthrin and identify the intermediates in culture broth using spectroscopy. An aerobic bacterium capable of degrading β-cyfluthrin was isolated by enrichment culture. The 16S ribosomal DNA sequence of the isolate (strain S1) had 100% identity to the sequence from Pseudomonas stutzeri. Finally products formed during degradation of β-cyfluthrin have been identified as α-cyano-4-fluoro-3-phenoxybenzyl-3(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylate (M.W. 341); 4-fluoro-3-phenoxy-α-cyanobenzyl alcohol (M.W. 243) and 3(2,2-dichlorovinyl)-2,2-dimethyl cyclopropanecarboxylic acid (M.W. 208).

Organochlorine insecticide residues in drinking and ground water in and around Delhi.

A multiresidue method was developed for the estimation of 15organochlorine pesticides in water. 50 samples of drinking watersupplied by the Municipal Corporation to the residential areasof Delhi and 20 ground water samples from nearby villages usedfor irrigation were monitored for the presence of organochlorineinsecticides by the method developed. Although, organochlorinepesticides were detected in the ground water and irrigationwater samples, the levels of pesticides were below the MaximumContaminant Level as prescribed by WHO. No organochlorineinsecticides were detected in any of the drinking water samples.

Degradation of beta‐endosulfan by Aspergillus Niger

Abstract The organochlorine insecticide endosulfan is a mixture of two stereoisomers, alpha and beta. The degradation of the more persistent beta isomer was shown using the soil microorganism Aspergillus niger. The relatively rapid rate of degradation of beta‐endosulfan as compared to control, formation of endosulfan diol and absence of formation of the toxic metabolite endosulfan sulfate suggest the possibility of developing a non‐chemical method for degrading endosulfan.

Nanosulfur: A Potent Fungicide Against Food Pathogen, Aspergillus niger

Elemental sulfur (S0), man’s oldest eco‐friendly fungicide for curing fungal infections in plants and animals, is registered in India as a non‐systemic and contact fungicide. However due to its high volume requirement, Indian agrochemical industry and farmers could not effectively use this product till date. We hypothesize that intelligent nanoscience applications might increase the visibility of nanosulfur in Indian agriculture as a potent and eco‐safe fungicide. Sulfur nanoparticles (NPs) were synthesized bottom‐up via a liquid synthesis method with average particle size in the range of 50–80 nm and the shapes of the NPs were spherical. A comparative study of elemental and nano‐sulfur produced has been tested against facultative fungal food pathogen, Aspergillus niger. Results showed that nanosulfur is more efficacious than its elemental form.

Development and evaluation of alginate-chitosan nanocapsules for controlled release of acetamiprid.

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.

Development of pyridalyl nanocapsule suspension for efficient management of tomato fruit and shoot borer (Helicoverpa armigera)

The objective of this study was to evaluate in vitro the insecticidal activity of pyridalyl nanosuspension in comparison to technical material and commercial formulation against larvae of Helicoverpa armigera. Suspension of pyridalyl nanocapsules was prepared, for reducing its dose of application. Compatibility of pyridalyl with sodium alginate was ascertained and a formulation was obtained by optimizing various parameters. Average micelle size of different formulations was around 138 nm and size of pyridalyl was less than 100 nm. Spherical shape and nanosize of capsules was confirmed by Transmission electron microscopy. Zeta potential of optimized formulation was found to be about (−)20 ± 1 Mv indicating acceptable range for expressing physical stability of the nano-capsules. The pyridalyl nanosuspension insecticidal activity increased remarkably, with LC50 values of 40 μg mL−1 in comparison to LC50 values of technical material (90 μg mL−1) and commercial product (250 μg mL−1). Bioassay results by leaf dip method showed that nanoformulation is 2.26 and 6.25 times more effective against H. armigera as stomach poison than the technical product and commercial formulation respectively. By topical method, the LC50 values obtained were 80, 150, and 250 μg mL−1 for nanoformulation, technical material, and commercial formulation, respectively, proving our hypothesis. Pyridalyl nanocapsule suspension performed effectively than technical material and commercial product against tomato fruit and shoot borer (Helicoverpa armigera), showing that insecticide load to the environment can be reduced by using nanoformulations.

Evaluation of performance and community dynamics of microorganisms during treatment of distillery spent wash in a three stage bioreactor

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.

Dissipation of 14C carbaryl and quinalphos in soil under a groundnut crop (Arachis hypogaea L.) in semi-arid India

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.