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 (RSDr ) ≤ 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.

Preparation of Polyacrylonitrile/Ni-MOF electrospun nanofiber as an efficient fiber coating material for headspace solid-phase microextraction of diazinon and chlorpyrifos followed by CD-IMS analysis.

Herein, an electrospun polyacrylonitrile/nickel-based metal-organic framework nanocomposite (PAN/Ni-MOF) coating on a stainless steel wire was synthesized and employed as a novel nanosorbent for headspace solid-phase microextraction (HS-SPME) of organophosphorus pesticides (OPPs), diazinon (DIZ), and chlorpyrifos (CPS) from the diverse aqueous media followed by corona discharge ion mobility spectrometry (CD-IMS). Under the optimum experimental conditions, the calibration plots were linear in the range of 1.0-250.0 ng mL-1 for DIZ and 0.5-300.0 ng mL-1 for CPS with r2 > 0.999. The detection limits (S/N = 3) were 0.3 and 0.2 ng mL-1 for DIZ and CPS, respectively. The intra-day relative standard deviations (RSDs%) (n = 5) at the concentration levels of 20.0, 40.0, and 100.0 ng mL-1 were ≤ 5.2%. To investigate the extraction efficiency, PAN/Ni-MOF was employed to analyze various juice samples, including orange, apple, and grape juices, and in three water samples where it led to good recoveries ranged between 87% and 98%.

A highly sensitive biosensor with a single-copy evolved sensing cassette for chlorpyrifos pesticide detection.

A formylglycine-generating enzyme (FGE)-sulfatase-based whole-cell biosensor was genetically improved into a single-copy system by integrating the Sinorhizobium meliloti transcriptional activator ChpR and the chpA promoter-FGE-sulfatase fusion into the Escherichia coli chromosome. The sensitivity was further enhanced through a random mutagenesis of the chpR. The new integrated biosensor offered both a lower detection limit [5 nM chlorpyrifos (CPF)] and fluorescence background. The ready-to-use kit was developed using silica gel for on-field detection. The biosensor kit was stable for 20 days when stored at 4 °C. Moreover, a 1-(1-naphthylmethyl)-piperazine (NMP) efflux pump inhibitor can improve the sensitivity by 57 %.

Selective solid-phase extraction of organophosphorus pesticides and their oxon-derivatives from water samples using molecularly imprinted polymer followed by high-performance liquid chromatography with UV detection.

A molecularly imprinted polymer was synthesized and characterized to be used as solid-phase extraction sorbent for simultaneous chlorpyrifos and diazinon and their oxon derivatives. Several imprinted polymers were prepared and evaluated in a retention study of these analytes compared with a non-printed polymer. Several parameters affecting the extraction of imprinted polymer such as washing solvent, composition and volume of the eluting solvent and sample volume, were also investigated. Under the optimum conditions, the developed method provided satisfactory limits of detection ranging between 0.07 µg L-1 to 0.12 µg L-1 and the material showed an excellent reusability (> 50 reuses). The method was applied to the extraction and preconcentration of these analytes in water samples. The average recoveries ranged from 79 ± 6 to 104 ± 3 %.

Optimization of a Simplified and Effective Analytical Method of Pesticide Residues in Mealworms (Tenebrio molitor Larvae) Combined with GC-MS/MS and LC-MS/MS.

An effective analytical method was optimized for residues including chlorpyrifos-methyl, deltamethrin, fenoxanil, thiobencarb and fludioxonil in mealworms, the larval form of Tenebrio molitor. They are listed for pest control during wheat cultivation and can be found in wheat-bran feed for growing mealworms in South Korea. Analytes were extracted using acetonitrile and salt packet. Four clean-up methods ((1) MgSO4 + 25 mg PSA + 25 mg C18; (2) MgSO4 + 50 mg PSA + 50 mg C18; (3) EMR-lipidTM tube; and (4) 10 mL n-hexane) were investigated and the method (1) was selected due to its robustness. Low-temperature precipitation of fat and proteins improved the recoveries. Recoveries from the Method (1) were satisfying with 70-120% with <20% relative SD at a spiking level of 0.01 mg/kg. With the simultaneous sample preparation, fenoxanil, thiobencarb and fludioxonil were analyzed by liquid chromatography tandem mass spectrometry (LC-MS/MS) and chlorpyrifos-methyl and deltamethrin by gas chromatography tandem mass spectrometry (GC-MS/MS). Quantification limits for LC-MS/MS and GC-MS/MS were 0.5 and 2.5 µg/L, respectively. No pesticides of interest were detected in 30 real samples collected across the nation. However, the data can be provided for establishing maximum residue limits for the pesticides in mealworms in response to the positive list system.

Magnetic amino-functionalized hollow silica-titania microsphere as an efficient sorbent for extraction of pesticides in green and roasted coffee beans.

This study describes the synthesis and application of a magnetic amino-functionalized hollow silica-titania microsphere as a new sorbent for magnetic dispersive micro-solid phase extraction of selected pesticides in coffee bean samples. The sorbent was fully characterized by Fourier-transform infrared spectroscopy, field emission scanning electron microscopy, transition electron microscopy, energy-dispersive X-ray spectroscopy, and vibrating sample magnetometry techniques. Significant extraction parameters affecting the proposed method, such as extraction time, sorbent amount, sample solution pH, salt amount, and desorption conditions (desorption solvent and time) were investigated and optimized. All the figures of merits were validated in coffee bean samples under the matrix-matched calibration method. Linear dynamic ranges were 5-250 µg/kg with the determination coefficients (R2 ) > 0.9980. The limits of detection for the pesticides of chlorpyrifos, malathion, hexaconazole, and atrazine were 1.42, 1.43, 1.35, and 1.33 µg/kg, respectively. Finally, the method was successfully applied for the determination of the pesticides in green and roasted coffee bean samples, and the obtained recoveries were in the range of 74-113% for spiked samples. The prepared sorbent could be used for the magnetic dispersive micro-solid phase extraction of pesticides in the plant-derived food matrix.

Mesoporous structured molecularly imprinted polymer with restricted access function for highly selective extraction of chlorpyrifos from soil.

Mesoporous structured molecularly imprinted polymers combined with restricted access materials (RAM-M-MIPs) were synthesized in this work, then RAM-M-MIPs were used as adsorbents in matrix solid phase dispersion (MSPD) to extract chlorpyrifos residues from soil. The RAM-M-MIPs with mesoporous structure increased adsorptive capacity and accelerated adsorption rate. At the same time, the RAM-M-MIPs with restricted access function showed good exclusion effect toward humic acid in the soil. In addition, the characteristics of RAM-M-MIPs were measured and the optimal experimental conditions of MSPD were explored. In MSPD, the extraction and clean-up procedures can be finished simultaneously, which saved the extraction time. The analyte eluted from soil was determined by LC-MS/MS. The recoveries were in the range of 93.5-106.1% and the relative standard deviations were in the range of 2.8-5.7% at the spiked soil levels of 0.10-10.00 ng g-1, the detection limit was 0.015 ng g-1. Based on these analytical validation results, the developed method can be a useful method to determine chlorpyrifos in soil.

Electrospun terpolymeric nanofiber membrane for micro solid-phase extraction of diazinon and chlorpyrifos from aqueous samples.

The present study deals with the synthesis and electrospining of a new terpolymer nanofiber in order to determine the amount of diazinon and chlorpyrifos in water and fruit juice samples. The synthesized terpolymer and the prepared nanofiber were characterized using 1 H NMR spectroscopy, FTIR spectroscopy, scanning electron microscopy, and gel permeation chromatography. The performance of terpolymer nanofiber, prepared as a sorbent for micro solid phase extraction was investigated for the extraction of diazinon and chlorpyrifos from aquaeous media. Then, the target analytes were desorbed from the coating with an organic solvent and analyzed by gas chromatography with flame ionization detector. Extraction efficiencies were significant (>90%) under the optimum condition. The proposed method also demonstrated good linear dynamic ranges for diazinon and chlorpyrifos (3-250 and 5-200 µg/L), and low limit of detections (0.5 and 0.7 µg/L) respectively. Moreover, under optimum condition for extraction of diazinon and chlorpyrifos, square of correlation coefficients (R2 ) of 0.9978 and 0.9953 and relative standard deviations of 4.6 and 5.1% were achieved, respectively. The recoveries for diazinon and chlorpyrifos were in the range of 85-97%.

Comparative study on the biodegradation of chlorpyrifos-methyl by Bacillus megaterium CM-Z19 and Pseudomonas syringae CM-Z6.

The strains CM-Z19 and CM-Z6, which are capable of highly degrading chlorpyrifos-methyl, were isolated from soil. They were identified as Bacillus megaterium CM-Z19 and Pseudomonas syringae CM-Z6, respectively, based on the 16S rRNA and an analysis of their morphological, physiological and biochemical characteristics. The strain CM-Z19 showed 92.6% degradation of chlorpyrifos-methyl (100 mg/L) within 5 days of incubation, and the strain CM-Z6 was 99.1% under the same conditions. In addition, the degradation characteristics of the two strains were compared and studied, and the results showed that the strain CM-Z19 had higher phosphoesterase activity and ability to degrade the organophosphorus pesticide than did the strain CM-Z6. However, the strain CM-Z19 could not degrade its first hydrolysis metabolite 3,5,6-trichloro-2-pyridinol (TCP) and could not completely degrade chlorpyrifos-methyl. The strain CM-Z6 could effectively degrade TCP and could degrade chlorpyrifos-methyl more quickly than strain CM-Z19.

Removal of chlorpyrifos, an insecticide using metal free heterogeneous graphitic carbon nitride (g-C3N4) incorporated chitosan as catalyst: Photocatalytic and adsorption studies.

The present study investigates the photocatalytic degradation of an organic pesticide using a metal free heterogeneous graphitic carbon nitride (g-C3N4) incorporated into chitosan as catalyst. Chlorpyrifos (O, O-diethylO-3,5,6-trichloro-2-pyridyl phosphorothioate (CPFS)), an insecticide includes in a class of Organophosphate pesticides with a chemical formula (C9H11Cl3NO3PS). It is widely used in agricultural lands to control pests in cotton, fruit and vegetables. The acute toxicity of chlorpyrifos is still dangerous to all aquatic living organisms. The CS/g-C3N4 materials have been characterized using UV-vis spectrophotometer (UV-vis), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscope (SEM), Energy Dispersive X-ray Analysis (EDX), Thermal analysis (TGA-DSC), Chemical oxygen demand (COD), X-ray diffraction (XRD), Diffuse reflectance spectra (DRS) and Electron spin resonance (ESR). The degradation of pesticide using CS/g-C3N4 showed good efficiency of about 85%. The results suggest that CS/g-C3N4 composite is a good alternative for the treatment of chlorpyrifos in aqueous solution. We have proposed a novel photocatalyst by metal free heterogeneous graphitic carbon using melamine and its recombination effects were minimized by chitosan which act as an electron carrier. The enhanced photocatalytic performance could be attributed to an efficient separation of electron-hole pairs through a Z-scheme mechanism, in which chitosan acted as charge separation carriers.

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]. / Vliianie fermentativnoi obrabotki kormovoi zernosmesi ot khlorpirifosa na biokhimicheskie pokazateli krovi krys.

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.

Methodology for trace analysis of 17 pyrethroids and chlorpyrifos in foodstuff by gas chromatography-tandem mass spectrometry.

This study aimed to develop an efficient, sensitive, and reliable analytical method for trace analysis of 17 different pyrethroids and chlorpyrifos in the fatty content of animal products, including beef, chicken, eggs, fish, and milk. The method developed is based on an ultrasound extraction using lyophilized samples, a solid phase extraction cleanup with basic alumina and C18 cartridges in tandem, and analysis by gas chromatography coupled to tandem mass spectrometry in negative chemical ionization mode. Recovery values were in the range of 27-128 % with relative standard deviation always below 25 %, and chiral analysis of recovery data showed predominance of isomers of cis form over trans. Limits of detection (LODs) ranged from 0.002 to 6.43 ng g-1 lipid weight (lw), and limits of quantification (LOQs) ranged between 0.006 and 21.4 ng g-1 lw. The developed methodology was used for the analysis of 25 samples of fatty foods. All samples were positive for at least one of the pesticides, chlorpyrifos, bifenthrin, cyhalothrin, permethrin, cypermethrin, or deltamethrin, with mass fraction levels ranging from 0.03 to 270 ng g-1 lw. Graphical Abstract ᅟ.

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.

Efficient Surface Display of Diisopropylfluorophosphatase (DFPase) in E. coli for Biodegradation of Toxic Organophosphorus Compounds (DFP and Cp).

Compounds including organophosphorus pesticides (OPs) and chemical nerve agents are toxic compounds synthesized recently which disrupt the mechanisms of neural transmission. Therefore, a critical requirement is the development of a bio-refining technology to facilitate the biodegradation of organophosphorus pollutants. The diisopropylfluorophosphatase (DFPase, EC 3.1.8.2) from the ganglion and brain of Loligo vulgaris acts on P-F bonds present in some OPs. Intracellular production of OPs-degrading enzymes or the use of native bacteria and fungi leads to a low degradation rate of OPs due to a mass transfer issue which reduces the overall catalytic efficiency. To overcome this challenge, we expressed DFPase on the surface of E. coli for the first time by employing the N-terminal domain of the ice nucleation protein (InaV-N) as an anchoring motif. Tracking the recombinant protein confirmed that DFPase is successfully located on the outer membrane. Further studies on its activity to degrade diisopropylfluorophosphate (DFP) showed its significant ability for the biodegradation of diisopropylfluorophosphate (DFP) with a specific activity of 500 U/mg of wet cell weight. Recombinant cells could also degrade chlorpyrifos (Cp) with an activity equivalent to a maximum value of 381.44 U/ml with a specific activity of 476.75 U/mg of cell, analyzed using HPLC technique. The optimum activity of purified DFPase was found at 30 °C. A more increased activity was also obtained in the presence of glucose-mineral-salt (GMS) supplemented with tryptone and 100 mg/L Co(2+) ion. These results highlight the high potential of the InaV-N anchoring domain to produce an engineered bacterium that can be used in the bioremediation of pesticide-contaminated environments.

Development, validation and determination of multiclass pesticide residues in cocoa beans using gas chromatography and liquid chromatography tandem mass spectrometry.

An efficient and rapid method for the analysis of pesticide residues in cocoa beans using gas and liquid chromatography-tandem mass spectrometry was developed, validated and applied to imported and domestic cocoa beans samples collected over 2 years from smallholders and Malaysian ports. The method was based on solvent extraction method and covers 26 pesticides (insecticides, fungicides, and herbicides) of different chemical classes. The recoveries for all pesticides at 10 and 50 µg/kg were in the range of 70-120% with relative standard deviations of less than 20%. Good selectivity and sensitivity were obtained with method limit of quantification of 10 µg/kg. The expanded uncertainty measurements were in the range of 4-25%. Finally, the proposed method was successfully applied for the routine analysis of pesticide residues in cocoa beans via a monitoring study where 10% of them was found positive for chlorpyrifos, ametryn and metalaxyl.

Vortex-assisted low density solvent liquid-liquid microextraction and salt-induced demulsification coupled to high performance liquid chromatography for the determination of five organophosphorus pesticide residues in fruits.

A simple and rapid microextraction method, vortex-assisted low density solvent liquid-liquid microextraction and salt-induced demulsification (VLLME-SID) coupled to high performance liquid chromatography (HPLC) was developed for the determination of organophosphorus pesticide (OPP) residues in fruits. The studied OPPs were azinphos-methyl, parathion-methyl, fenitrothion, diazinon and chlorpyrifos. For VLLME-SID, a mixture of low density solvents (1-dodecanol and hexane) was used as the extraction solvent under vortex agitation for enhancing dispersion. After complete dispersion, the emulsion was formed and the OPPs were extracted into extraction solvent droplets. Then, the emulsion was quickly broken up into two clear phases after the addition of AlCl3 as a demulsifier. Centrifugation was not required in this procedure. Under the optimal conditions, high enrichment factors (180-282), low limit of detections (LODs) (0.05-1 ng mL(-1)) and good precision (RSD≤7% for retention time and peak area) were obtained. The proposed method was successfully applied to the analysis of OPP residues in fruit samples (watermelon, grape, and cantaloupe). The LODs for samples were in the range 0.0006-0.0015 mg kg(-1) which are below the established EU-MRLs (0.01-0.3 mg kg(-1)). Good recoveries were also obtained (80-104%).

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.