Determination of organophosphorus and synthetic pyrethroid pesticide residues and their variability in large size fruit crops

BACKGROUND

Variability of pesticide residues in food item plays a key role for the evaluation of consumer food safety. However, variability factors (VFs) derived from the large size fruit crops are still scarce. Therefore, the present work was aimed to quantify pesticide residues and to estimate VFs in large size fruit crops of mango and guava.

RESULTS

A total of 140 mango and 130 guava samples from different marketplaces in Bangladesh were collected to estimate the variability of pesticide residues (acephate, diazinon, malathion, fenitrothion, chlorpyrifos, quinalphos, dimethoate and cypermethrin) by in-house validated methods based on modified QuEChERS extraction and gas chromatography coupled with electron capture detector (ECD) and flame thermionic detector (FTD). The method was validated at three fortification levels (0.01, 0.10 and 0.30 mg kg^-1 ) and satisfactory recoveries (80-111%) with relative standard deviation (RSD_r ) ≤ 13% were achieved. A wide variation of residues was found in the analyzed samples. In the case of mango, the ranges of residues were 0.011-0.314, 0.015-0.04, and 0.05-0.291 mg kg^-1 , respectively, for cypermethrin, chlorpyrifos, and dimethoate, while in the case of guava, the ranges were 0.04-0.113, and 0.03-0.290 mg kg^-1 , respectively, for cypermethrin and acephate. The average VF for mango was 4.06 and it was 5.70 for guava.

CONCLUSION

VFs originating from the marketed samples of mango and guava are reported in this study for the first time. The estimated VFs were higher than the default value of 3, therefore, the default VFs should be reconsidered when more data are obtained regarding large size crops. © 2021 Society of Chemical Industry.

Removal of chlorpyrifos in recirculating vertical flow constructed wetlands with five wetland plant species

The removal efficiency of the pesticide chlorpyrifos (50 and 500 μg L^-1) by five wetland plant species (Cyperus alternifolius, Canna indica, Iris pseudacorus, Juncus effusus and Typha orientalis) was studied in recirculating vertical flow constructed wetland systems (RVFCWs). Results reveal that for chlorpyrifos at different concentrations, good removal efficiencies (94-98%) were observed using the same plant systems, while no significant differences in removal efficiencies were seen between the different plant systems. In addition, the chlorpyrifos removal efficiency of the planted systems increased significantly compared with the unplanted controls. The chlorpyrifos removal efficiency for wetland systems over time fit to the first-order kinetic model, with the first-order kinetic constant (k) ranging from 0.045 to 0.065 h^-1. The half-life of chlorpyrifos in the systems ranged from 10.66-15.43 h. The shortest chlorpyrifos half-life was detected in the wetland system containing C. indica, followed by that with C. alternifolius and I. pseudacorus. The main pathways to remove chlorpyrifos in these wetland systems were sorption (accounting for 64.6-86.4% of the total removal efficiency) and biodegradation (8.1-33.7%). Plants can enhance chlorpyrifos removal through enhanced biodegradation in the system. Plants with high biomass and transpiration were able to accelerate the removal of chlorpyrifos and conventional pollutants. Hence, C. indica, C. alternifolius and I. pseudacorus could be used as optimal plants for pesticide removal in wetland systems.

Organophosphorus pesticide mixture removal from environmental matrices by a soil Streptomyces mixed culture

The current study aimed to evaluate the removal of a pesticide mixture composed of the insecticides chlorpyrifos (CP) and diazinon (DZ) from liquid medium, soil and a biobed biomixture by a Streptomyces mixed culture. Liquid medium contaminated with 100 mg L^-1 CP plus DZ was inoculated with the Streptomyces mixed culture. Results indicated that microorganisms increased their biomass and that the inoculum was viable. The inoculum was able to remove the pesticide mixture with a removal rate of 0.036 and 0.015 h^-1 and a half-life of 19 and 46 h^-1 for CP and DZ, respectively. The sterilized soil and biobed biomixture inoculated with the mixed culture showed that Streptomyces was able to colonize the substrates, exhibiting an increase in population determined by quantitative polymerase chain reaction (q-PCR), enzymatic activity dehydrogenase (DHA) and acid phosphatase (APP). In both the soil and biomixture, limited CP removal was observed (6-14%), while DZ exhibited a removal rate of 0.024 and 0.060 day^-1 and a half-life of 29 and 11 days, respectively. Removal of the organophosphorus pesticide (OP) mixture composed of CP and DZ from different environmental matrices by Streptomyces spp. is reported here for the first time. The decontamination strategy using a Streptomyces mixed culture could represent a promising alternative to eliminate CP and DZ residues from liquids as well as to eliminate DZ from soil and biobed biomixtures.

[The influence of enzymatic removal of chlorpyrifos from feed grain-mixture on the biochemical parameters of rat blood]

Organophosphorus pesticides (OP) are used to protect crops from pests. Treatment of plants and animals with pesticides can be done during their growth or creation of conditions necessary for the long-shelf life of the agricultural products. Currently, there are many remedies for prevention and removal of intoxication consequences developed under the action of OP in living organisms. The development of biologics for the degradation of OP and biotechnologies for their application in agriculture is relevant. New biologics based on the stabilized forms of such enzyme as hexahistidine-tagged organophosphorus hydrolase (His6-OPH) in the form of nano-sized particles were tried for OP detoxification. These biologics (enzyme-polyelectrolyte complexes, EPC) were obtained in accordance to previously developed procedure by mixing solutions of His6-OPH and polyanion under certain conditions. The main purpose of this work was to evaluate the usage efficiency of EPC based on His6-OPH and polyglutamic acid for OP detoxification by analyzing biochemical blood parameters of rats consumed the grain-mixture containing chlorpyrifos. The experiment was conducted using female Sprague Dawley albino rats. Treatment of feeding grain-mixture initially containing chlopyrifos (48 mg/kg of the mixture) with EPC based on His6-OPH (1000 U/kg of the mixture) for 24 h was the most effective. The results showed that rats from the group consuming food after enzymatic removal of chlorpyrifos, had comparable acetyl cholinesterase activity in blood of rats consuming pure food (without any OP intoxication).

Removal of pesticides and ecotoxicological changes during the simultaneous treatment of triazines and chlorpyrifos in biomixtures

Biopurification systems constitute a biological approach for the treatment of pesticide-containing wastewaters produced in agricultural activities, and contain an active core called biomixture. This work evaluated the performance of a biomixture to remove and detoxify a combination of three triazine herbicides (atrazine/terbuthylazine/terbutryn) and one insecticide (chlorpyrifos), and this efficiency was compared with dissipation in soil alone. The potential enhancement of the process was also assayed by bioaugmentation with the ligninolytic fungi Trametes versicolor. Globally, the non-bioaugmented biomixture exhibited faster pesticide removal than soil, but only in the first stages of the treatment. After 20 d, the largest pesticide removal was achieved in the biomixture, while significant removal was detected only for chlorpyrifos in soil. However, after 60 d the removal values in soil matched those achieved in the biomixture for all the pesticides. The bioaugmentation failed to enhance, and even significantly decreased the biomixture removal capacity. Final removal values were 82.8% (non-bioaugmented biomixture), 43.8% (fungal bioaugmented biomixture), and 84.7% (soil). The ecotoxicological analysis revealed rapid detoxification (from 100 to 170 TU to <1 TU in 20 d) towards Daphnia magna in the biomixture and soil, and slower in the bioaugmented biomixture, coinciding with pesticide removal. On the contrary, despite important herbicide elimination, no clear detoxification patterns were observed in the phytotoxicity towards Lactuca sativa. Findings suggest that the proposed biomixture is useful for fast removal of the target pesticides; even though soil also removes the agrochemicals, longer periods would be required. On the other hand, the use of fungal bioaugmentation is discouraged in this matrix.

Biotreatment of chlorpyrifos in a bench scale bioreactor using Psychrobacter alimentarius T14

Bacteria tolerant to high pesticide concentration could be used for designing an efficient treatment technology. Bacterial strains T14 was isolated from pesticide-contaminated soil in mineral salt medium (MSM) and identified as Psychrobacter alimentarius T14 using 16S rRNA gene sequence analysis. Bench scale bioreactor was evaluated for biotreatment of high Chlorpyrifos (CP) concentration using P. alimentarius T14. Effect of various parameters on bioreactor performance was examined and optimum removal was observed at optical density (OD600 nm): 0.8; pH: 7.2; CP concentration: 300 mg L(-1) and hydraulic retention time: 48 h. At optimum conditions, 70.3/79% of CP/chemical oxygen demand (COD) removal was achieved in batch bioreactors. In addition, P. alimentarius T14 achieved 95/91, 62.3/75, 69.8/64% CP/COD removal efficiency with addition of CS (co-substrates), CS1 (yeast extract + synthetic wastewater), CS2 (glucose + synthetic wastewater) and CS3 (yeast extract), respectively. Addition of CS1 to bioreactor could accelerate CP removal rate up to many cycles with considerable efficiency. However, accumulation of 3, 5, 6-trichloro-2-pyridinol affects reactor performance in cyclic mode. First-order rate constant k1 0.062 h(-1) and t1/2 11.1 h demonstrates fast degradation. Change in concentration of total chlorine and nitrogen could be the result of complete mineralization. Photodegradation of CP in commercial product was more than its pure form. Commercial formulation accelerated photodegradation process; however no effect on biodegradation process was observed. After bio-photodegradation, negligible toxicity for seeds of Triticum aestivum was observed. Study suggests an efficient treatment of wastewater containing CP and its metabolites in batch bioreactors could be achieved using P. alimentarius.

Influence of the pesticides glyphosate, chlorpyrifos and atrazine on growth parameters of nonochratoxigenic Aspergillus section Nigri strains isolated from agricultural soils

This investigation was undertake to determine the effect of glyphosate, chlorpyrifos and atrazine on the lag phase and growth rate of nonochratoxigenic A. niger aggregate strains growing on soil extract medium at -0.70, -2.78 and -7.06 MPa. Under certain conditions, the glyphosate concentrations used significantly increased micelial growth as compared to control. An increase of about 30% was observed for strain AN 251 using 5 and 20 mg L(-1) of glyphosate at -2.78 MPa. The strains behaved differently in the presence of the insecticide chlorpyrifos. A significant decrease in growth rate, compared to control, was observed for all strains except AN 251 at -2.78 MPa with 5 mg L(-1). This strain showed a significant increase in growth rate. With regard to atrazine, significant differences were observed only under some conditions compared to control. An increase in growth rate was observed for strain AN 251 at -2.78 MPa with 5 and 10 mg L(-1) of atrazine. By comparison, a reduction of 25% in growth rate was observed at -7.06 MPa and higher atrazine concentrations. This study shows that glyphosate, chlorpyrifos and atrazine affect the growth parameters of nonochratoxigenic A. niger aggregate strains under in vitro conditions.

Immobilized graphene-based composite from asphalt: facile synthesis and application in water purification

An in situ strategy for the preparation of graphene immobilized on sand using asphalt, a cheap carbon precursor is presented. The as-synthesized material was characterized in detail using various spectroscopic and microscopic techniques. The presence of G and D bands at 1578 cm(-1) and 1345 cm(-1) in Raman spectroscopy and the 2D sheet-like structure with wrinkles in transmission electron microscopy confirmed the formation of graphenic materials. In view of the potential applicability of supported graphenic materials in environmental application, the as-synthesized material was tested for purifying water. Removal of a dye (rhodamine-6G) and a pesticide (chlorpyrifos), two of the important types of pollutants of concern in water, were investigated in this study. Adsorption studies were conducted in batch mode as a function of time, particle size, and adsorbent dose. The continuous mode experiments were conducted in multiple cycles and they confirmed that the material can be used for water purification applications. The adsorption efficacy of the present adsorbent system was compared to other reported similar adsorbent systems and the results illustrated that the present materials are superior. The adsorbents were analyzed for post treatment and their reusability was evaluated.

[Biodegradation mechanism of DDT and chlorpyrifos using molecular simulation]

In order to explore the microscopic degradation mechanism of organic pesticides degrading enzymes, we used molecular docking method to investigate the binding modes of DDT to laccase and chlorpyrifos to organophosphorus hydrolase, and obtained the corresponding complex structures. According to the principle of minimum scoring, the results showed that the MolDock scores were -103.134 and -111.626, re-rank scores were -72.858 and -80.261, respectively. And we used LPC/CSU server search the interactions between organic pesticides and their degrading enzymes. Our results showed that hydrophobic interaction was the strongest contacts in DDT-laccase complex, and both hydrogen bonds and hydrophobic interactions were the strongest contacts when chlorpyrifos-organophosphorus hydrolase complex. The amino acid residues Tyr224 in laccase and Arg254 in organophosphorus hydrolase were detected to play significant roles in catalytic processes.

Competitive immunochromatographic assay for the detection of the organophosphorus pesticide chlorpyrifos

An immunochromatographic assay (ICA) based on competitive antigen-coated format using colloidal gold as the label was developed for the detection of the organophosphorus insecticide chlorpyrifos. The ICA test strip consisted of a membrane with a detection zone, a sample pad and an absorbent pad. The membrane was separately coated with chlorpyrifos Hapten-OVA conjugate (test line) and anti-mouse IgG (control line). Based on the fact that the competition is between the migrating analyte in the sample and the analyte hapten immobilized on the test strip for the binding sites of the antibody-colloidal gold (Ab-CG) conjugate migrating on the test strip, this study suggests that the relative migration speed between the two migrating substances is a critically important factor for the sensitive detection by competitive ICA. This criterion was utilized for the confirmation of appropriateness of a nitrocellulose (NC) membrane for chlorpyrifos ICA. The detection limit of the ICA for chlorpyrifos standard and chlorpyrifos spiked into agricultural samples were 10 and 50 ng mL(-1), respectively. The assay time for the ICA test was less than 10 min, suitable for rapid on-site testing of chlorpyrifos.

[Thermodynamics adsorption and its influencing factors of chlorpyrifos and triazophos on the bentonite and humus]

The adsorption of chlorpyrifos and triazophos on bentonite and humus was investigated by using the equilibrium oscillometry. The adsorption capacity of chlorpyrifos and triazophos on humus was great higher than bentonite at the same concentration. Equilibrium data of Langmuir, Freundlich isotherms showed significant relationship to the adsorption of chlorpyrifos and triazophos on humus (chlorpyrifos: R2 0.996 4, 0.996 3; triazophos: R2 0.998 9, 0.992 4). Langmuir isotherm was the best for chlorpyrifos and triazophos on bentonite (chlorpyrifos: R2 = 0.995 7, triazophos: R2 = 0.998 9). The pH value, adsorption equilibrium time and temperature were the main factors affecting adsorption of chlorpyrifos and triazophos on bentonite and humus. The adsorption equilibrium time on mixed adsorbent was 12h for chlorpyrifos and 6h for triazophos respectively. The mass ratio of humus and bentonite was 12% and 14% respectively, the adsorption of chlorpyrifos and triazophos was the stronglest and tended to saturation. At different temperatures by calculating the thermodynamic parameters deltaG, deltaH and deltaS, confirmed that the adsorption reaction was a spontaneous exothermic process theoretically. The adsorption was the best when the pH value was 6.0 and the temperature was 15 degrees C.

Chlorpyrifos and atrazine removal from runoff by vegetated filter strips: experiments and predictive modeling

Runoff volume and flow concentration are hydrological factors that limit effectiveness of vegetated filter strips (VFS) in removing pesticides from surface runoff. Empirical equations that predict VFS pesticide effectiveness based solely on physical characteristics are insufficient on the event scale because they do not completely account for hydrological processes. This research investigated the effect of drainage area ratio (i.e., the ratio of field area to VFS area) and flow concentration (i.e., uniform versus concentrated flow) on pesticide removal efficiency of a VFS and used these data to provide further field verification of a recently proposed numerical/empirical modeling procedure for predicting removal efficiency under variable flow conditions. Runoff volumes were used to simulate drainage area ratios of 15:1 and 30:1. Flow concentration was investigated based on size of the VFS by applying artificial runoff to 10% of the plot width (i.e., concentrated flow) or the full plot width (i.e., uniform flow). Artificial runoff was metered into 4.6-m long VFS plots for 90 min after a simulated rainfall of 63 mm applied over 2 h. The artificial runoff contained sediment and was dosed with chlorpyrifos and atrazine. Pesticide removal efficiency of VFS for uniform flow conditions (59% infiltration; 88% sediment removal) was 85% for chlorpyrifos and 62% for atrazine. Flow concentration reduced removal efficiencies regardless of drainage area ratio (i.e., 16% infiltration, 31% sediment removal, 21% chlorpyrifos removal, and 12% atrazine removal). Without calibration, the predictive modeling based on the integrated VFSMOD and empirical hydrologic-based pesticide trapping efficiency equation predicted atrazine and chlorpyrifos removal efficiency under uniform and concentrated flow conditions. Consideration for hydrological processes, as opposed to statistical relationships based on buffer physical characteristics, is required to adequately predict VFS pesticide trapping efficiency.

Extraction of chlorpyrifos and malathion from water by metal nanoparticles

The nanoparticles of gold and silver in solution state and supported over activated alumina are effective systems for the quantitative removal of chlorpyrifos and malathion, two common pesticides found in surface waters of developing nations, from water. In the solution phase, these pesticides adsorb onto the nanoparticles' surfaces and upon interaction for a long time, the nanoparticles with adsorbed pesticides precipitate. In contrast, complete removal of these pesticides occurs when contaminated water is passed over nanoparticles supported on alumina. A prototype of an on-line filter was made using a column of activated alumina powder loaded with silver nanoparticles and the device was used for pesticide removal for extended periods. We believe that the method has great technological potential in drinking water purification, especially using silver nanoparticles.

Solving liquid chromatography mass spectrometry coelution problems in the analysis of environmental samples by multivariate curve resolution

Multivariate curve resolution-alternating least squares (MCR-ALS) is shown to be a powerful tool to resolve coelution problems in liquid chromatograpy-mass spectrometry (LC-MS) in scan mode. This investigation was performed using two types of LC columns, one traditional LC column of 25 cm length with a slow gradient and a shorter LC column of 7.5 cm with a rapid gradient which allowed much faster analysis and save of reagents and solvents. Mixtures of multiple biocide compounds were simultaneously analyzed in standard mixtures and in environmental samples (sediment and wastewater samples) with little sample pretreatment. Using the more traditional LC 25 cm column, all biocide compounds were properly resolved by MCR-ALS and quantitatively analyzed with estimated errors always below 20%. When fast chromatography (LC column of 7.5 cm) was used, MCR-ALS resolution of the more strongly coeluted compounds was also achieved but limitations were found in their simultaneous quantitative determination, specially for environmental samples.

Dissipation of chlorpyrifos on pakchoi inside and outside greenhouse

The dissipation of chlorpyrifos on pakchoi inside and outside greenhouse was studied. The decline curve of chlorpyrifos on pakchoi could be described as first-order kinetic. The experimental data showed that both the hermetic environment of greenhouse and season affected dissipation rates of chlorpyrifos on pakchoi. Chlorpyrifos declined faster outside greenhouse than inside greenhouse. Chlorpyrifos residues at pre-harvest time were below the maximum residue limits (MRLs) fixed in China, whereas the values inside greenhouse were higher than those outside greenhouse by almost 50%. The recommended pre-harvest time established under conditions of open field might not always fit to greenhouse production.

Supercritical fluid extraction of chlorpyrifos and 3,5,6-trichloro-2-pyridinol from garden compost

A method was developed for the simultaneous supercritical carbon dioxide extraction of chlorpyrifos and its primary degradate, 3,5,6-trichloro-2-pyridinol (TCP), from garden compost. In situ derivatization with N,O-bis(trimethylsilyl)trifluoracetamide was necessary for extraction of TCP. Recoveries for TCP and chlorpyrifos were quantitative for spiked compost samples. Sodium chloride was used as the packing material in extractions with in situ derivatization. Optimum results were obtained for air-dried samples containing 4-7% moisture. No sample cleanup was required prior to analysis by GC-flame ionization detection. The effects of compost moisture content and ageing were investigated for chlorpyrifos recovery. No significantly negative effect on recovery for up to 20% (w/w) moisture for chlorpyrifos was observed. Effects of ageing showed a decrease in extraction efficiency over time with 52% recovery after 10 days.

Column extraction of chlorpyrifos from contaminated fish

A method for measuring chlorpyrifos in fish, which combines extraction, filtration, and cleanup in one step, is described. Minced fish samples were mixed with potassium dihydrogen phosphate and disodium hydrogen phosphate, ground with anhydrous sodium sulfate, and eluted from a prepacked chromatographic column containing silica gel. The endogenous coextractives were retained by the column while chlorpyrifos was quantitatively eluted with 40 mL of 5% ether in hexane. Recoveries averaged 86.8% for unexposed fish fortified with 2-12 ppm of chlorpyrifos. The method was applied to the analysis of fish from a lagoon contaminated with chlorpyrifos by a spray treatment of a wooden bridge for termites.