Magnetic Solid-Phase Extraction (MSPE) Using Magnetite-Based Core-Shell Nanoparticles with Silica Network (SiO2) Coupled with GC-MS/MS Analysis for Determination of Multiclass Pesticides in Water.

BACKGROUND: For the analysis of pesticide residues in water samples, various extraction techniques are available. However, liquid-liquid extraction (LLE) and solid-phase extraction (SPE) are most commonly used. LLE and SPE extraction techniques each have their own disadvantages. OBJECTIVE: The aim of the study was to develop an environment-friendly multi-residue method for determination of multiclass pesticides in environmental water samples (ground water, agricultural field/irrigation run-off water, etc.). METHODS: The magnetic solid-phase extraction (MSPE) technique using surface-fabricated magnetic nano-particles was used for extraction of water samples, followed by quantification by gas chromatography tandem mass spectrometry. The developed multi-residue method was validated in terms of linearity, LOD, LOQ, recovery, and repeatability. RESULTS: Recovery data were obtained at the spiking concentration level of 1, 5, and 10 µg/L, yielding recoveries in the range of 70-120%. Overall, non-polar pesticides from all the groups, i.e., synthetic pyrethroid, organophosphorus, organochlorine, herbicides, and fungicides, show acceptable recovery percentages. Good linearity (r2 value ≥ 0.99) was observed at the concentration range of 0.5-100 µg/L. RSD values were found ≤ 18.8. CONCLUSIONS: The study shows that the method is specific, rapid, and low cost, as well as having a good linearity and recovery; thus, this method is applied in routine purposes for the analysis of pesticide residue in real water samples. HIGHLIGHTS: Due to better adsorption ability, permeability, and magnetic separability, the functionalized nano-particles were found effective in the enrichment of 22 multiclass pesticides including organo-phosphorus, organo-chlorine, synthetic pyrethroid, herbicides, and fungicides.

Determination of Organophosphorous Pesticides in Environmental Water Samples Using Surface-Engineered C18 Functionalized Silica-Coated Core-Shell Magnetic Nanoparticles-Based Extraction Coupled with GC-MS/MS Analysis.

The present paper depicts a novel method based on magnetic SPE (MSPE) for the determination of organophosphorus pesticides (OPs) such as phorate, malathion, and chlorpyrifos in environmental water samples. In this study, C18 functionalized silica-coated core-shell iron oxide magnetic nanoparticles (MNPs) were used as a surface-engineered magnetic sorbent for the selective extraction of pesticides from aqueous samples, followed by GC-MS and GC-tandem MS analysis for confirmative determination of the analytes. Various important method parameters, including quantity of MNP adsorbent, volume of sample, effective time for extraction, nature of the desorbing solvent, and pH of the aqueous sample, were investigated and optimized to obtain maximum method performance. Under the optimized instrumental analysis conditions, good linearity (r2 value ≥0.994) was achieved at the concentration range of 0.5-500 µg/L. Recoveries were in the range of 79.2-96.3 and 80.4-97.5% in selective-ion monitoring and multiple reaction monitoring (MRM) modes, respectively, at the spiking concentrations of 1, 5, and 10 µg/L. MRM mode showed better sensitivity, selectivity, and low-level detection (0.5 µg/L) of analytes. The novel MSPE method is a simple, cheap, rapid, and eco-friendly method for the determination of OPs in environmental water samples.

Metabolism and dissipation kinetics of a novel protoporphyrinogen IX oxidase herbicide [oxadiargyl] in various buffered aqueous system under laboratory-simulated condition.

Present investigation was carried out using two commercial products Raft (oxadiargyl 6% EC) and Topstar (oxadiargyl 80% WP) of Oxadiargyl {5-tert-butyl-3[2,4-dichloro-5-(prop-2-ynyloxy)phenyl]-1,3,4-oxadiazol-2 (3H)-one} to investigate the persistence behavior and metabolism of the herbicide in various aqueous system under different pH condition. Half-life values revealed that alkaline hydrolysis played a dominant role in hydrolytic degradation of this compound. Q-ToF micromass study with the alkaline fractions of oxadiargyl indicated the formation of five metabolites, which was further characterized from their mass fragmentation data. The nature of metabolites formed indicated that heterocyclic oxadiazoline ring cleavage was found to be the main pathway of hydrolytic transformation of oxadiargyl.

Synthesis and surface engineering of magnetic nanoparticles for environmental cleanup and pesticide residue analysis: a review.

In recent years, water pollution and pesticide accumulation in the food chain have become a serious environmental and health hazard problem. Direct determination of these contaminants is a difficult task due to their low concentration level and the matrix interferences. Therefore, an efficient separation and preconcentration procedure is often required prior to the analysis. With the advancement in nanotechnology, various types of magnetic core-shell nanoparticles have successfully been synthesized and received considerable attention as sorbents for decontamination of diverse matrices. Magnetic core-shell nanoparticles with surface modifications have the advantages of large surface-area-to-volume ratio, high number of surface active sites, no secondary pollutant, and high magnetic properties. Due to their physicochemical properties, surface-modified magnetic core-shell nanoparticles exhibit high adsorption efficiency, high rate of removal of contaminants, and easy as well as rapid separation of adsorbent from solution via external magnetic field. Such facile separation is essential to improve the operation efficiency. In addition, reuse of nanoparticles would substantially reduce the treatment cost. In this review article, we have attempted to summarize recent studies that address the preconcentration methods of pesticide residue analysis and removal of toxic contaminants from aquatic systems using magnetic core-shell nanoparticles as adsorbents.

Dissipation kinetics of tetraconazole in three types of soil and water under laboratory condition.

Laboratory experiment was conducted to understand the persistence behavior of tetraconazole in three soils of West Bengal (alluvial, red lateritic, and coastal saline) and also in water maintained at three different pH (4.0, 7.0, and 9.2) conditions. Processed soil samples (100 g) were spiked at two treatment doses: 2.5 µg/g (T1) and 5.0 µg/g (T2). Double distilled buffered water (200 ml) was spiked at two treatment doses: 1.0 µg/ml (T1) and 2.00 µg/ml (T2). The tetraconazole dissipation followed first-order reaction kinetics and the residual half-life (T1/2) values in soil were found to be in the range of 66.9-77.2 days for T1 and 73.4-86.0 days for T2. The persistence increased in the order red lateritic > new alluvial > coastal saline. Interestingly, the red lateritic soil exhibited the lowest pH (5.56) and organic carbon (0.52%) content as compared to other two soils. However, the dissipation of tetraconazole in case of water was not pH dependant. The T1/2 values in water were in the range of 94 to 125 days. The study indicated the persistent nature of tetraconazole in soil and water.

Residual fate of the fungicide tetraconazole (4% EW) in mango.

A field trial was carried out to understand the persistence behaviour of tetraconazole in mango and also in the soil of mango orchard following five applications @ 50 g a.i./ha (T(1)) and 100 g a.i./ha (T(2)). The initial deposits were found to be 0.23 and 0.38 µg/g for T(1) and T(2) doses. The theoretical maximum residue contribution (TMRC) of tetraconazole in dietary exposure appeared to be toxicologically safe for consumption as compared with maximum permissible intake (MPI). The half-life values of tetraconazole in mango were in the range of 4-5 days. The harvest samples of mango and soil were free from tetraconazole residues.

Development, validation, and uncertainty measurement of multi-residue analysis of organochlorine and organophosphorus pesticides using pressurized liquid extraction and dispersive-SPE techniques.

Simple and efficient multi-residue analytical methods were developed and validated for the determination of 13 organochlorine and 17 organophosphorous pesticides from soil, spinach and eggplant. Techniques namely accelerated solvent extraction and dispersive SPE were used for sample preparations. The recovery studies were carried out by spiking the samples at three concentration levels (1 limit of quantification (LOQ), 5 LOQ, and 10 LOQ). The methods were subjected to a thorough validation procedure. The mean recovery for soil, spinach and eggplant were in the range of 70-120% with median CV (%) below 10%. The total uncertainty was evaluated taking four main independent sources viz., weighing, purity of the standard, GC calibration curve and repeatability under consideration. The expanded uncertainty was well below 10% for most of the pesticides and the rest fell in the range of 10-20%.

Impact assessment and decontamination of pesticides from meat under different culinary processes.

A total of 75 animals between 1.5 and 8 years old were randomly selected for the study. Of these, 57.8% were cross-bred animals and the rest were non-descript. Moreover, 61.8% of the animals under study were brought for slaughter from local sources and the rest from farm houses. Samples collected from five districts revealed contamination with traces of organochlorine pesticides (0.01-0.22 microg g(-1)) and organophosphorus pesticides (0.111-0.098 microg g(-1)). In general, all the raw meat samples possessed dichlorodiphenyltrichloroethane at the highest level. Contamination was highest in cow meat samples and lowest in chicken samples. No particular district-wise trend was obtained for the pesticides selected for analysis. Subsequent decontamination study revealed that cooking is the best option in reducing pesticide load in raw meat samples. Cooked chicken is the safest foodstuff for consumption.

Risk assessment and chemical decontamination of an oxime carbamate insecticide (methomyl) from eggplant, Solanum melongena L.

Methomyl, S-methyl (EZ)-N-(methylcarbamoyloxy)thioacetimidate, is a systemic insecticide chosen for the management of shoot and fruit borer, Leucinodes orbonalis G. Codex Alimentarious Commission has proposed a maximum residue limit (MRL) of 0.2 mg kg( - 1) of methomyl, and there is a need to validate this value on eggplant. First + first-order model can explain the nonlinear dissipation pattern of methomyl conveniently in comparison to first-order kinetics. The preharvest intervals (PHI) of 27.3 and 35.3 days as obtained from first + first-order model for single and double doses would bring down the methomyl residue below MRL in actual practice. The respective half-lives were 6.6 and 7.8 days. On the other hand, first-order model suggests methomyl dissipated with a half-life value around 5 days and proposed PHIs of 6.57 and 8.57 days for single and double doses, which was far from reality. Hence, five different decontamination agents were chosen for the decontamination of methomyl from eggplant. Safety factors such as theoretical maximum daily intake and maximum permissible intake were used to evaluate risk assessment to human health. A 3-day waiting period for the both doses, following conventional agricultural practice and processing factor could not ensure sufficient margin of safety. Subjecting the data to a processing factor of 60% could not bring the residues below the proposed MRL by Codex. Methomyl is not found appropriate and effective for application in eggplant. Either the proposed MRL needs to be revised or good agricultural practice involving methomyl for plant protection in eggplant cultivation is questioned.

Antiulcer activity of methanolic extract of Momordica charantia L. in rats.

AIM OF THE STUDY: Momordica charantia L. (Cucurbitaceae) commonly known as 'bitter gourd' is a multi purpose herb cultivated in different parts of the world for its edible fruits. The objective of the present study was to evaluate the effect of standardized methanolic extract of Momordica charantia L. fruits on gastric and duodenal ulcers. MATERIALS AND METHODS: The effect was evaluated in acetic acid induced chronic gastric ulcer, pylorus ligation induced gastric ulcer, ethanol induced gastric ulcer, stress induced gastric ulcer, indomethacin induced gastric ulcer and cysteamine induced duodenal ulcer model. The extract was administered orally at two different doses of 100 mg/kg and 500 mg/kg. RESULTS: The healing of acetic acid induced gastric ulcer was increased by both doses of the extract. In pylorus-ligated rats, the extract showed significant decrease in ulcer index, total acidity, free acidity and pepsin content and an increase in gastric mucosal content. The extract also reduced the ulcer index in stress induced, ethanol induced and indomethacin induced gastric ulcers and cysteamine induced duodenal ulcer. CONCLUSION: The methanolic extract of Momordica charantia L. fruit increases healing of gastric ulcer and also prevents development of gastric ulcers and duodenal ulcers in rats.

A multi-residue method for the analysis of organophosphorus residues in cooked and polished rice using accelerated solvent extraction and dispersive-solid phase extraction (D-SPE) technique and uncertainty measurement.

Quick, simple and efficient multi-residue analytical methods were developed and validated for the determination of organophosphorous insecticides from polished and cooked rice. Polished rice was extracted using a simple, automated technique namely accelerated solvent extraction (ASE) using dichloromethane as the extraction solvent. Cooked rice was extracted with acetone and cleaned up using dispersive-solid phase extraction (D-SPE) technique. The single step extraction method adopted for polished rice using accelerated solvent extractor provided satisfactory recovery for eight organophosphorus pesticides (OPPs) which ranged from 85.5-116.7%; 90.0-110.3% and 93.5-118.8% at 1, 5 and 10 limit of quantification (LOQ) levels, respectively. The recovery of cooked rice was in the range of 74-124%; from 75-100% and from 73-87% for 1, 5 and 10 level of fortification, respectively. The total uncertainty was evaluated, taking four main independent sources viz., weighing, purity of the standard, GC calibration curve and repeatability under consideration. The expanded uncertainty was found to be in the range of 5-20%.

Genetic variation of wild and hatchery populations of the catla Indian major carp (Catla catla Hamilton 1822: Cypriniformes, Cyprinidae) revealed by RAPD markers.

Genetic variation is a key component for improving a stock through selective breeding programs. Randomly amplified polymorphic DNA (RAPD) markers were used to assess genetic variation in three wild population of the catla carp (Catla catla Hamilton 1822) in the Halda, Jamuna and Padma rivers and one hatchery population in Bangladesh. Five decamer random primers were used to amplify RAPD markers from 30 fish from each population. Thirty of the 55 scorable bands were polymorphic, indicating some degree of genetic variation in all the populations. The proportion of polymorphic loci and gene diversity values reflected a relatively higher level of genetic variation in the Halda population. Sixteen of the 30 polymorphic loci showed a significant (p < 0.05, p < 0.01, p < 0.001) departure from homogeneity and the F(ST) values in the different populations indicated some degree of genetic differentiation in the population pairs. Estimated genetic distances between populations were directly correlated with geographical distances. The unweighted pair group method with averages (UPGMA) dendrogram showed two clusters, the Halda population forming one cluster and the other populations the second cluster. Genetic variation of C. catla is a useful trait for developing a good management strategy for maintaining genetic quality of the species.

Genetic variation of wild and hatchery populations of the catla Indian major carp (Catla catla Hamilton 1822: Cypriniformes, Cyprinidae) revealed by RAPD markers

Genetic variation is a key component for improving a stock through selective breeding programs. Randomly amplified polymorphic DNA (RAPD) markers were used to assess genetic variation in three wild population of the catla carp (Catla catla Hamilton 1822) in the Halda, Jamuna and Padma rivers and one hatchery population in Bangladesh. Five decamer random primers were used to amplify RAPD markers from 30 fish from each population. Thirty of the 55 scorable bands were polymorphic, indicating some degree of genetic variation in all the populations. The proportion of polymorphic loci and gene diversity values reflected a relatively higher level of genetic variation in the Halda population. Sixteen of the 30 polymorphic loci showed a significant (p < 0.05, p < 0.01, p < 0.001) departure from homogeneity and the F ST values in the different populations indicated some degree of genetic differentiation in the population pairs. Estimated genetic distances between populations were directly correlated with geographical distances. The unweighted pair group method with averages (UPGMA) dendrogram showed two clusters, the Halda population forming one cluster and the other populations the second cluster. Genetic variation of C. catla is a useful trait for developing a good management strategy for maintaining genetic quality of the species.

Characterization of different strains of common carp (Cyprinus carpio L) (Cyprinidae, Cypriniformes) in Bangladesh using microsatellite DNA markers

Characterization of different strains of common carp (Cyprinus carpio L.) using molecular markers is essential for the management of this fish in respect to the evaluation of the potential genetic effects induced by hatchery operations and the genetic improvement of carp varieties. Five microsatellite loci (MFW1, MFW2, MFW11, MFW15 and MFW20) were analyzed for the molecular characterization of four common carp strains, i.e. scaled carp, mirror carp, red carp and koi carp. We observed differences in heterozygosities and the average numbers of alleles but not in polymorphic loci (P95) among the strains. Koi carp displayed the highest level of variability in terms of heterozygosity. The Nm values and the F ST values indicated a low level of gene flow and high level of differentiation among the strains. The highest genetic distance was observed between the scaled carp and the koi carp whilst the lowest genetic distance was found between the red- and koi carp. The unweighted pair group method with averages (UPGMA) dendrogram resulted in two clusters, one containing only the scaled carp and the other the remaining three varieties. Microsatellite markers have been found to be effective tools for characterization of different strains of common carp.