Efficient and selective extraction of azamethiphos and chlorpyrifos residues from mineral water and grape samples using magnetic mesoporous molecularly imprinted polymer.

A magnetic mesoporous molecularly imprinted polymers was synthesized on the surface of magnetic nanoparticles silanized with 3-(trimethoxysilyl) propyl methacrylate to introduce reactive methacrylate groups. Subsequently, methacrylic acid monomers were grafted onto the surface of this adsorbent functionalized via polymerization by precipitation. Magnetic mesoporous molecularly imprinted polymer was properly characterized by different techniques and applied as adsorbent in magnetic solid phase extraction for selective determination of two organophosphorus pesticides, azamethiphos and chlorpyrifos, in mineral water and grape samples. After sample preparation optimization, recoveries of 99.56% and 98.86% were obtained for azamethiphos and chlorpyrifos, respectively. The magnetic solid phase extraction coupled to HPLC-UV presented limit of quantification of 5 ng mL-1, linearity ranged of 5 to 1000 ng mL-1, in addition to adequate accuracy, precision and robustness. The pesticides showed stability in the matrix and were satisfactorily quantified in real mineral water and grape samples.

Experimental design of switchable solvent-based liquid phase microextraction for the accurate determination of etrimfos from water and food samples at trace levels by GC-MS.

Presented in this study is a simple but efficient switchable polarity solvent microextraction strategy for etrimfos preconcentration from water and food samples for quantification by gas chromatography mass spectrometry. Repeatability of the extraction process and instrumental measurements were enhanced by using deuterated bisphenol A as internal standard. Significant parameters of the extraction method were fitted into an experimental design model to study the effects of parameters on extraction output, as well as mutual effects of combined parameters. The design model was formed with 51 experimented data obtained from the combination of sodium hydroxide volume, switchable solvent volume, and vortex period at three levels. The method was validated by applying optimum conditions attained from the model predictor. The detection limit was found to be 1.3 ng/mL and it corresponded to an enhancement factor of about 54 folds when compared to direct GC-MS measurement. Etrimfos was not detected in the water and food samples tested but the results (92-107%) obtained from spiked recovery experiments established that etrimfos when present in the selected matrices can be accurately and precisely quantified.

Aberrations of the peripheral erythrocytes and its recovery patterns in a freshwater teleost, silver barb exposed to profenofos.

The present experiment was conducted to explicate the genotoxic effects of profenofos, an organophosphate insecticide, on the erythrocytes of silver barb (Barbonymus gonionotus). Silver barb were exposed to a solution of 10% and 50% of lethal concentrations (LC50) of profenofos as sub-lethal concentrations at different days (1, 7, 15, and 30 d), along with a control (0% profenofos). Subsequent recovery patterns were assessed allowing the fish exposed to profenofos free water for the same period that they were exposed to profenofos. Our results revealed that with the progression of time and concentration, fish exposed to profenofos showed significantly (p < .05) higher level of erythrocytic nuclear abnormalities (ENA) such as micronuclei, bi-nuclei, degenerated nuclei, notched nuclei, nuclear bridge and nuclear buds, as well as erythrocytic cellular abnormalities (ECA) such as echinocytic, elongated, fusion, spindle, tear-drop and twin shaped cells. After exposure, the silver barb recovered spontaneously, and the abnormal erythrocytic parameters were normalized with a concentration- and duration-dependent fashion. Therefore, these abnormalities and their recovery can be used to assess the toxic levels of pesticides on aquatic organisms. There is great potential to use this technique as in vivo to predict susceptibility of aquatic animals to environmental pollution.

Triazophos (TAP) removal in horizontal subsurface flow constructed wetlands (HSCWs) and its accumulation in plants and substrates.

Triazophos (TAP) is a widely used phosphorus pesticide in China that possesses a potential risk for water pollution. We have studied the removal efficiency of TAP using pilot-scale horizontal subsurface flow constructed wetlands (HSCWs) as well as the contribution of plants, substrates and other pathways to its removal. For TAP concentrations of 0.12 ± 0.04 mg L-1, 0.79 ± 0.29 mg L-1 and 3.96 ± 1.17 mg L-1, the removal efficiencies were 94.2 ± 3.7%, 97.8 ± 2.9% and 84.0 ± 13.5%, respectively, at a hydraulic loading rate (HLR) of 100 mm d-1; at an HLR of 200 mm d-1, the removal efficiencies were 96.7 ± 1.3%, 96.2 ± 1.7% and 61.7 ± 11.1%, respectively. The isopleth maps of TAP along the direction of flow indicate that most of the TAP removal occurred in the front and middle regions, while the major removal region would move forward with increasing influent TAP. Plant and substrate accumulation accounted for 0.035 ± 0.034% and 4.33 ± 0.43% of the total removal, respectively, indicating that over 95% of the TAP removal was achieved through other mechanisms. Thus, these results suggest HSCWs can be an effective approach with which to treat TAP contaminated water. Furthermore, the longitudinal scale and hydraulic conditions, as well as the roles of plants, substrates and microbes and their interactions, should be further considered in the design and application of CWs for pesticide pollution control.

Fiber optic profenofos sensor based on surface plasmon resonance technique and molecular imprinting.

A successful approach for the fabrication and characterization of an optical fiber sensor for the detection of profenofos based on surface plasmon resonance (SPR) and molecular imprinting is introduced. Molecular imprinting technology is used for the creation of three dimensional binding sites having complementary shape and size of the specific template molecule over a polymer for the recognition of the same. Binding of template molecule with molecularly imprinted polymer (MIP) layer results in the change in the dielectric nature of the sensing surface (polymer) and is identified by SPR technique. Spectral interrogation method is used for the characterization of the sensing probe. The operating profenofos concentration range of the sensor is from 10(-4) to 10(-1)µg/L. A red shift of 18.7 nm in resonance wavelength is recorded for this profenofos concentration range. The maximum sensitivity of the sensor is 12.7 nm/log (µg/L) at 10(-4)µg/L profenofos concentration. Limit of detection (LOD) of the sensor is found to be 2.5×10(-6)µg/L. Selectivity measurements predict the probe highly selective for the profenofos molecule. Besides high sensitivity due to SPR technique and selectivity due to molecular imprinting, proposed sensor has numerous other advantages like immunity to electromagnetic interference, fast response, low cost and capability of online monitoring and remote sensing of analyte due to the fabrication of the probe on optical fiber.

Combined treatment technology based on synergism between hydrodynamic cavitation and advanced oxidation processes.

The present work highlights the novel approach of combination of hydrodynamic cavitation and advanced oxidation processes for wastewater treatment. The initial part of the work concentrates on the critical analysis of the literature related to the combined approaches based on hydrodynamic cavitation followed by a case study of triazophos degradation using different approaches. The analysis of different combinations based on hydrodynamic cavitation with the Fenton chemistry, advanced Fenton chemistry, ozonation, photocatalytic oxidation, and use of hydrogen peroxide has been highlighted with recommendations for important design parameters. Subsequently degradation of triazophos pesticide in aqueous solution (20 ppm solution of commercially available triazophos pesticide) has been investigated using hydrodynamic cavitation and ozonation operated individually and in combination for the first time. Effect of different operating parameters like inlet pressure (1-8 bar) and initial pH (2.5-8) have been investigated initially. The effect of addition of Fenton's reagent at different loadings on the extent of degradation has also been investigated. The combined method of hydrodynamic cavitation and ozone has been studied using two approaches of injecting ozone in the solution tank and at the orifice (at the flow rate of 0.576 g/h and 1.95 g/h). About 50% degradation of triazophos was achieved by hydrodynamic cavitation alone under optimized operating parameters. About 80% degradation of triazophos was achieved by combination of hydrodynamic cavitation and Fenton's reagent whereas complete degradation was achieved using combination of hydrodynamic cavitation and ozonation. TOC removal of 96% was also obtained for the combination of ozone and hydrodynamic cavitation making it the best treatment strategy for removal of triazophos.

Poly(ionic liquid) immobilized magnetic nanoparticles as new adsorbent for extraction and enrichment of organophosphorus pesticides from tea drinks.

New poly(ionic liquid) immobilized magnetic nanoparticles (PIL-MNPs) were synthesized via co-polymerization of 1-vinyl-3-hexylimidazolium-based ionic liquid and vinyl-modified magnetic particles and were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, and magnetic measurements. The PIL-MNPs were utilized as adsorbent phases in magnetic solid-phase extraction (MSPE). The extraction and enrichment efficiency were evaluated by using four organophosphorus pesticides (parathion, fenthion, phoxim and temephos) as test analytes. Various parameters, such as amount of adsorbent, adsorption time, desorption solvent and time, and ionic strength were investigated. The proposed method showed good linearity for the analytes in the concentration range of 1-200µgL(-1) with a correlation coefficient (R)>0.9963. Low limit of detection of 0.01µgL(-1) and high enrichment factors ranging from 84 to 161 were achieved. The proposed method has been successfully used to determine organophosphorus pesticides from three tea drink samples with satisfactory recovery of 81.4-112.6% and RSDs of 4.5-11.3%. The PIL-MNP adsorbent can be reused for 20 times without a noticeable decrease in extraction efficiency.

Development of a home-made extraction device for vortex-assisted surfactant-enhanced-emulsification liquid-liquid microextraction with lighter than water organic solvents.

We have developed a novel vortex-assisted surfactant-enhanced-emulsification liquid-liquid microextraction using the low density solvent for the determination of eight organophosphorus pesticides (OPPs) in water samples. The key point of this method is the application of a special home-made extraction device. The influence parameters relevant to this method were systemically investigated and the optimum conditions were as follow: 35µL of toluene was used as extraction solvent and 0.2mmol L-1 Triton X-100 was chosen as the surfactant to enhance the emulsification. Under the optimum experimental conditions, the limit of detections (LODs) of the method was ranged between 0.01 and 0.05µgL(-1) and the relative standard deviations (RSDs) were 2.9-8.1%. The calibration curve was linear in the range of 0.1-50.0µgL(-1), with the correlation coefficients (r) varying from 0.9949 to 0.9991. Finally, the developed method has been successfully applied to the determination of eight organophosphorus pesticides in river, reservoir and well water samples with recoveries between 82.1% and 98.7%.

Dispersive liquid-liquid microextraction of pesticides and metabolites from soils using 1,3-dipentylimidazolium hexafluorophosphate ionic liquid as an alternative extraction solvent.

In this work, the use of the ionic liquid (IL) 1,3-dipentylimidazolium hexafluorophosphate ([PPIm][PF6]) as an alternative extractant for IL dispersive liquid-liquid microextraction (IL-DLLME) of a group of pesticides and metabolites (2-aminobenzimidazole, carbendazim/benomyl, thiabendazole, fuberidazole, carbaryl, 1-naphthol, and triazophos) from soils is described. After performing an initial ultrasound-assisted extraction (USE), the IL-DLLME procedure was applied for the extraction of these organic analytes from soil extracts. Separation and quantification was achieved by high-performance liquid chromatography (HPLC) with fluorescence detection (FD). Calibration, precision, and accuracy of the described USE-IL-DLLME-HPLC-FD method using [PPIm][PF6] as an alternative extractant was evaluated with two soils of different physicochemical properties. Accuracy percentages were in the range 93-118% with RSD values below 20%. A comparison of the performance of [PPIm][PF6] versus that of the so-common 1-hexyl-3-methylimidazolium hexafluorophosphate ([HMIm][PF6]) was accomplished. Results indicate a comparable extraction efficiency with both ILs, being slightly higher with [HMIm][PF6] for the metabolite 2-aminobenzimidazole, and slightly higher with [PPIm][PF6] for triazophos. In all cases, LODs were in the low ng/g range (0.02-14.2 ng/g for [HMIm][PF6] and 0.02-60.5 ng/g for [PPIm][PF6]). As a result, the current work constitutes a starting point for the use of the IL [PPIm][PF6] for further analytical approaches.

Enantiomeric separation and toxicity of an organophosporus insecticide, pyraclofos.

Despite the fact that the biological processes of chiral pesticides are enantioselective, knowledge of the toxicities of pyraclofos due to enantiospecificity is scarce. In this study, the optical isomers of pyraclofos were separated and their toxicities to butyrylcholinesterase (BChE) and Daphnia magna were assessed. Baseline resolution of the enantiomers was obtained on both Chiralcel OD and Chiralpak AD columns. The effect of the mobile phase composition and column temperature were then discussed. The resolved enantiomers were characterized by their optical rotation and circular dichroism signs. The anti-BChE tests demonstrated that (-)-pyraclofos was about 15 times more potent than its (+)-form. However, acute aquatic assays suggested that (+)-pyraclofos was about 6 times more toxic than its antipode. Moreover, the joint toxicity of pyraclofos enantiomers to D. magna was found to be an additive effect. These results demonstrated that the overall toxicity of pyraclofos should be assessed using the individual enantiomers.

[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.

[Analysis of demeton-S-methyl, oxydemeton-methyl and demeton-S-methylsulfone in agricultural products by LC-MS].

We studied the simultaneous determination of demeton-S-methyl, oxydemeton-methyl, and their oxide demeton-S-methylsulfone, in agricultural products by liquid chromatography coupled with mass spectrometry (LC-MS). The sample homogenized with antioxidants L-ascorbic acid and butylhydroxytoluene was extracted with acetone. An aliquot of the crude extract was reextracted with ethyl acetate by using an EXtrelut column. After hexane/acetonitrile partitioning lipid-rich samples such as cereals, the extract was cleaned up on a PSA column or tandem graphitized carbon/PSA column, and determined by ESI-SIM mode LC-MS. Average recoveries (n=5) of compounds from ten kinds of samples fortified at the analyte concentration of 0.05 microg/g were from 73.8% to 102.5%, and the relative standard deviations were

Separation and toxicity of salithion enantiomers.

Enantioseletive toxicities of chiral pesticides have become an environmental concern recently. In this study, we evaluated the enantiomeric separation of salithion on a suite of commercial chiral columns and assessed the toxicity of enantiomers toward butyrylcholinesterase and Daphnia magna. Satisfactory separations of salithion enantiomers could be achieved on all tested columns, that is, Chiralcel OD, Chiralcel OJ, and Chiralpak AD column. However, the Chiralpak AD column offered the best separation and was chosen to prepare micro-scale of pure salithion enantiomers for subsequent bioassays. The first and second enantiomers eluted on the Chiralpak AD column were further confirmed to be (-)-S-salithion and (+)-R-salithion, respectively. The half inhibition concentrations to butyrylcholinesterase of racemate, (+)-R-salithion, and (-)-S-salithion were 33.09, 2.92, and 15.60 mg/l, respectively, showing (+)-R-enantiomer being about 5.0 times more potent than its (-)-S-form. However, the median lethal concentrations (96 h) of racemate, (+)-R-salithion, and (-)-S-salithion toward D. magna were 3.54, 1.10, and 0.36 microg/l, respectively, suggesting that (-)-S-salithion was about 3.0 times more toxic than (+)-R-form. Racemic salithion was less toxic than either of the enantiomers in both bioassays, suggesting that antagonistic interactions might occur between the enantiomers during the toxication action. This work reveals that the toxicity of salithion toward butyrylcholinesterase and D. magna is enantioselective, and this factor should be taken into consideration in the environmental risk assessment of salithion.

Sorption of organophosphorous pesticides onto chickpea husk from aqueous solutions.

The sorption efficiency of chickpea husk of black gram variety (BGH), for the removal of organophosphorous pesticides (OPPs), i.e. triazophos (TAP) and methyl parathion (MP) from aqueous media has been investigated. Optimization of operating sorption parameters, i.e. particle size, sorbent dose, agitation time, pH, initial concentration of sorbates, and temperature has been studied. The sorption data fitted well to Freundlich, Langmuir and Dubinin-Radushkevich (D-R) sorption isotherms. The maximum sorption capacities of BGH for TAP and MP were calculated to be 3.5+/-0.45 and 10.6+/-0.83 mmol g(-1) by Freundlich, 0.0077+/-0.021 and 0.025+/-0.0094 mmol g(-1) by Langmuir and 0.48+/-0.037 and 0.15+/-0.077 mmol g(-1) by D-R isotherms respectively, employing 0.2g of sorbent, at pH 6, 90 min agitation time and at 303 K. Application of first order Lagergren and Morris-Weber equations to the kinetic data yielded correlation coefficients, close to unity and showed partial intra-particle diffusion. The negative values of thermodynamic parameters, i.e. DeltaH (kJ mol(-1)), DeltaS (J mol(-1) K(-1)) and DeltaG (kJ mol(-1)) indicate the exothermic and spontaneous nature of the sorption process. The sorbed pesticides were recovered by sonication with methanol, making the regeneration and reutilization of the sorbents promising. The investigated sorbent exhibited potential applications in water decontamination, treatments of industrial and agricultural waste waters and thus productively demonstrated viable use of agricultural waste material.

Application of dispersive liquid-liquid microextraction for the analysis of triazophos and carbaryl pesticides in water and fruit juice samples.

In this work, a simple, rapid and sensitive sample pretreatment technique, dispersive liquid-liquid microextraction (DLLME) coupled with high performance liquid chromatography-fluorescence detection (HPLC-FLD), has been developed to determine carbamate (carbaryl) and organophosphorus (triazophos) pesticide residues in water and fruit juice samples. Parameters, affecting the DLLME performance such as the kind and volume of extraction and dispersive solvents, extraction time and salt concentration, were studied and optimized. Under the optimum extraction conditions (extraction solvent: tetrachloroethane, 15.0 microL; dispersive solvent: acetonitrile, 1.0 mL; no addition of salt and extraction time below 5s), the performance of the proposed method was evaluated. The enrichment factors for the carbaryl and triazophos were 87.3 and 275.6, respectively. The linearity was obtained in the concentration range of 0.1-1000 ng mL(-1) with correlation coefficients from 0.9991 to 0.9999. The limits of detection (LODs), based on signal-to-noise ratio (S/N) of 3, ranged from 12.3 to 16.0 pg mL(-1). The relative standard deviations (RSDs, for 10 ng mL(-1) of carbaryl and 20 ng mL(-1) of triazophos) varied from 1.38% to 2.74% (n=6). The environmental water (at the fortified level of 1.0 ng mL(-1)) and fruit juice samples (at the fortified level of 1.0 and 5.0 ng mL(-1)) were successfully analyzed by the proposed method, and the relative recoveries of them were in the range of 80.4-114.2%, 89.8-117.9% and 86.3-105.3%, respectively.

Biodegradation of coumaphos, chlorferon, and diethylthiophosphate using bacteria immobilized in Ca-alginate gel beads.

Calcium-alginate immobilized cell systems were developed for the detoxification and biodegradation of coumaphos, an organophosphate insecticide, and its hydrolysis products, chlorferon and diethlythiophosphate (DETP). Optimum bead loadings for bioreactor operation were found to be 200 g-beads/L for chlorferon degradation and 300 g-beads/L for DETP degradation. Using waste cattle dip (UCD) solution as substrate, the degradation rate for an immobilized consortium of chlorferon-degrading bacteria was five times greater than that for freely suspended cells, and hydrolysis of coumaphos by immobilized OPH(+)Escherichia coli was 2.5 times greater. The enhanced degradation of immobilized cells was due primarily to protection of the cells from inhibitory substances present in the UCD solution. In addition, physiological changes of the cells caused by Ca-alginate immobilization may have contributed to increased reaction rates. Degradation rates for repeated operations increased for successive batches indicating that cells became better adapted to the reaction conditions over time.

Utilization of organic by-products for the removal of organophosphorous pesticide from aqueous media.

Sorption potential of rice (Oryza sativa) bran and rice husk for the removal of triazophos (TAP), an organophosphate pesticide, has been studied. The specific surface area were found to be 19+/-0.7 m(2)g(-1) and 11+/-0.8m(2)g(-1) for rice bran and rice husk, respectively. Rice bran exhibited higher removal efficiency (98+/-1.3%) than rice husk (94+/-1.2%) by employing triazophos solution concentration of 3 x 10(-5) M onto 0.2 g of each sorbent for 120 min agitation time at pH 6 and 303 K. The concentration range (3.2-32) x 10(-5) M was screened and sorption capacities of rice bran and rice husk for triazophos were computed by different sorption isotherms. The energy of sorption for rice bran and rice husk was assessed as 14+/-0.1 and 11+/-0.2 kJ mol(-1) and kinetics of the sorption is estimated to be 0.016+/-0.002 and 0.013+/-0.002 min(-1), respectively. Intraparticle diffusion rate was computed to be 4+/-0.8 and 4+/-0.9 nmol g(-1)min(-1/2). Thermodynamic constants DeltaH, DeltaS and DeltaG at varying temperatures (283-323 K) were also calculated.

Nonaqueous and aqueous-organic media for the enantiomeric separations of neutral organophosphorus pesticides by CE.

The enantiomeric separation of some poorly water-soluble organophosphorus pesticides (OPs) has been investigated using nonaqueous solvent and aqueous-organic solvent systems. In this work, sodium cholate (SC) either with SDS or gamma-CD was used to achieve enantiomeric separations of four neutral and poorly water-soluble OPs, i.e., profenofos, prothiofos, sulprofos, and pyraclofos. Electrophoretic medium consisted of a mixture of methanol (MeOH) with ACN (4:1 v/v) or a mixture of MeOH with H(2)O and ACN (5:4:1 v/v/v). On one hand, NACE was applied for enantiomeric separation of pyraclofos using a large amount of chiral and achiral surfactants (SC and SDS). On the other hand, H(2)O was added to act as a solvent additive to increase the solubility of gamma-CD in the organic solvents such as MeOH and ACN, in which the solubility of gamma-CD was very low. The presence of H(2)O was found to be particularly useful for the enantiomeric separation of profenofos, prothiofos, and sulprofos. In this way, the range of application of the neutral CDs in CE has been extended. In addition, SC was used as the only electrolyte. The proposed method has been applied for the analysis of soil samples.

Single-based resolution for oligodeoxynucleotides and their phosphorothioate modifications by replaceable capillary gel electrophoresis.

A replaceable capillary gel electrophoretic (replaceable CGE) method was developed for the separation of two sets of model compounds of single-stranded oligodeoxynucleotide mixtures (18-20 mers), phosphodiester oligodeoxynucleotides (PO-ODNs) and their phosphorothioate modifications (PS-ODNs), with equal sequences differing in a single base. Polyethylene glycol (PEG) 35000 was chosen as the sieving matrix. It was confirmed that PEG polymer solution less influenced resolutions of the PS-ODNs compared with those of the PO-ODNs, while acetonitrile used as an additive in the system improved the separation significantly. It was also noticed that the effect of temperature on separation was much larger than that of denaturant urea.