Determination Of Organophosphorus Pesticides Research Articles

Homogeneous Liquid-Liquid Microextraction for Determination of Organophosphorus Pesticides in Environmental Water Samples Prior to Gas Chromatography-Flame Photometric Detection.

In this study, homogeneous liquid-liquid microextraction (HLLME) was developed for preconcentration and extraction of 15 organophosphorus pesticides (OPPs) from water samples coupling with gas chromatography followed by a flame photometric detector (HLLME-GC-FPD). In this method, OPPs were extracted by the homogeneous phase in a ternary solvent system (water/acetic acid/chloroform). The homogeneous solution was excluded by the addition of sodium hydroxide as a phase separator reagent and a cloudy solution was formed. After centrifugation (3 min at 5,000 rpm), the fine particles of extraction solvent (chloroform) were sedimented at the bottom of the conical test tube (10.0 ± 0.5 µL). Furthermore, 0.5 µL of the sedimented phase was injected into the GC for separation and determination of OPPs. Optimal results were obtained under the following conditions: volume of the extracting solvent (chloroform), 53 µL; volume of the consolute solvent (acetic acid), 0.76 mL and concentration of sodium hydroxide, 40% (w/v). Under the optimum conditions, the enrichment factors of (260-665), the extraction percent of 75.8-104%, the dynamic linear range of 0.03-300 µg L(-1) and the limits of detection of 0.004-0.03 µg L(-1) were obtained for the OPPs. This method was successfully applied for the extraction and determination of the OPPs in environmental water samples.

Development of a Biosensor Based on Phosphotriesterase and n‐Channel ISFET for Detection of Pesticides

AbstractA biosensor for the direct determination of organophosphorus pesticides (OPs) is described. It utilizes an ion‐selective field‐effect transistor and phosphotriesterase enzyme (PTE), which provides cleavage of OPs. The sensitivity of the biosensor was increased after PTE immobilization on the surface of the transistor. Packaging of the integrated circuit and creation of a microfluidic system for analyte delivery stabilized the signal. This system was able to detect 0.1 µM paraoxon and 0.5 µM parathion and methyl parathion and was stable for at least 1 month (PBS, 1°), and could thus provide the basis for a portable device for analyzing OPs in water.

Sensitive and selective fluorescent chemosensor for the detection of some organophosphorus pesticides using luminescent Eu(III) complex

Abstract A new luminescent europium- o -(4-methoxy benzoyl) benzoic acid [ o -(4-anisoyl)] complex in ethanol–water (5:5 v/v) solution was used for selective determination of organophosphorus pesticides. The interaction of new and selective luminescent europium complex with different pesticides was studied using electroanalytical methods and fluorescence technique. The results indicate that the pesticides azinphos ethyl, chlorfenvinphos, diazinon and isofenphos, exhibit quenching effect on the characteristics emission peak for Eu(III) at λ = 614 nm. The luminescence variations values using the probe Eu-( o -(4-anisoyl)) 2 fit Stern–Volmer equation, where the detection limits are 1.93, 2.82, 3.78 and 1.80 μmol L −1 for azinphos ethyl, chlorfenvinphos, diazinon and isofenphos, respectively. The binding constants at different temperatures were calculated. Also, it was found that the quenching mechanism is dynamic type for chlorfenvinphos, diazinon and isofenphos while static type for azinphos ethyl. Effect of some relevant interferents on the detection of pesticides has been investigated.

An effective surface design based on a conjugated polymer and silver nanowires for the detection of paraoxon in tap water and milk

In this study, a novel approach for the fabrication of a biosensor utilizing a conducting polymer and silver nanowires is reported. To obtain immobilization platform for butyrylcholinesterase (BChE), a graphite electrode was modified with the poly(5,6-bis(octyloxy)-4,7-di(thieno[3][3,2-b]thiophen-2-yl)benzo[c][1,2,5]oxoadiazole) (PTTBO) which has a hydrophobic alkyl chain as the pendant group providing hydrophobic nature to the matrix. Since biomolecules contain both hydrophobic and hydrophilic parts in their structure, alkyl chains interact with the proteins which provide an enhanced stability. Biosensor performance was improved through the deposition of silver nanowires on the polymer coated surfaces which enhances the charge transfer rate. This enabled the development of rapid, highly sensitive and stable amperometric sensors for the quantitative determination of organophosphorus pesticide; paraoxon. Fabricated biosensor showed two linear ranges between 0.5–8μM and 10–120μM with a low detection limit of 0.212μM when butyryl thiocholine iodide is used as the substrate. Surface modifications were monitored by scanning electron microscope (SEM) and cyclic voltammetry (CV) techniques. Under optimal operational parameters, fabricated sensors were tested for paraoxon detection in milk and tap water based on the inhibition of the enzyme molecules, where recovery tests proved the applicability of the designed system.

Dispersive solid phase extraction followed by low-toxicity vortex-assisted liquid–liquid microextraction for the determination of organophosphorus pesticides by high-performance liquid chromatography

A simple, rapid and environmentally friendly method for the determination of OPPs in soil and cucumber samples was developed by using DSPE-LT-VALLME and HPLC-UV.

Highly-sensitive organophosphorus pesticide biosensors based on CdTe quantum dots and bi-enzyme immobilized eggshell membranes.

An optical biosensing method using CdTe quantum dots (QDs) and bi-enzyme-immobilized eggshell membranes for the determination of organophosphorus pesticides (OPs) has been developed. Increasing amounts of OPs led to a decrease of the enzymatic activity and thus a decrease in the production of hydrogen peroxide (H2O2), which can quench the fluorescence of the CdTe QDs. Under the optimum conditions, there was a good linear relationship between the enzyme inhibition percentage and the logarithm of paraoxon or parathion concentration in the range of 1.0 × 10(-11)-1.0 × 10(-6) mol L(-1). The detection limit (S/N = 3) of the proposed biosensors were as low as 4.30 × 10(-12) mol L(-1) for paraoxon and 2.47 × 10(-12) mol L(-1) for parathion. The bi-enzyme-immobilized eggshell membrane demonstrated a long shelf-life of at least 2 months and the results showed good repeatability. The proposed method was successfully applied to the determination of the OPs in real fruit samples with satisfactory results.

Ultrapreconcentration and determination of organophosphorus pesticides in water by solid-phase extraction combined with dispersive liquid-liquid microextraction and high-performance liquid chromatography.

Solid-phase extraction coupled with dispersive liquid-liquid microextraction was developed as an ultra-preconcentration method for the determination of four organophosphorus pesticides (isocarbophos, parathion-methyl, triazophos and fenitrothion) in water samples. The analytes considered in this study were rapidly extracted and concentrated from large volumes of aqueous solutions (100 mL) by solid-phase extraction coupled with dispersive liquid-liquid microextraction and then analyzed using high performance liquid chromatography. Experimental variables including type and volume of elution solvent, volume and flow rate of sample solution, salt concentration, type and volume of extraction solvent and sample solution pH were investigated for the solid-phase extraction coupled with dispersive liquid-liquid microextraction with these analytes, and the best results were obtained using methanol as eluent and ethylene chloride as extraction solvent. Under the optimal conditions, an exhaustive extraction for four analytes (recoveries >86.9%) and high enrichment factors were attained. The limits of detection were between 0.021 and 0.15 μg/L. The relative standard deviations for 0.5 μg/L of the pesticides in water were in the range of 1.9-6.8% (n = 5). The proposed strategy offered the advantages of simple operation, high enrichment factor and sensitivity and was successfully applied to the determination of four organophosphorus pesticides in water samples.

Extraction of organophosphorus pesticides by carbon-coated Fe3 O4 nanoparticles through response surface experimental design.

In this paper, carbon-coated Fe3 O4 nanoparticles were successfully synthesized and used as a magnetic solid-phase extraction absorbent for the preconcentration and extraction of organophosphorus pesticides in environmental water samples. The carbon-coated Fe3 O4 nanoparticles were characterized by transmission electron microscopy, X-ray powder diffraction, Fourier transform infrared spectroscopy, and vibrating sample magnetometry. The determination of organophosphorus pesticides in water samples with carbon-coated Fe3 O4 nanoparticles was investigated by high-performance liquid chromatography with a diode array detector. Furthermore, the response surface model based on the central composite design was applied to quantitatively investigate the effect of some important variables influencing the extraction efficiency, such as pH, treatment time, amount of nanoparticle sorbents, and amount of salt and to find the optimized conditions providing the highest extraction efficiency. Under optimized conditions, the calibration curve was linear in the range of 0.5-15.0 ng/mL with a regression coefficient of 0.9948, 0.9958, and 0.9931 for fenitrothion, diazinon, and ethion, respectively. The obtained results showed that this analytical method would be useful for the analysis of fenitrothion, diazinon, and ethion in tap water with high precision and accuracy.

Polyol-enhanced dispersive liquid-liquid microextraction coupled with gas chromatography and nitrogen phosphorous detection for the determination of organophosphorus pesticides from aqueous samples, fruit juices, and vegetables.

Polyol-enhanced dispersive liquid-liquid microextraction has been proposed for the extraction and preconcentration of some organophosphorus pesticides from different samples. In the present study, a high volume of an aqueous phase containing a polyol (sorbitol) is prepared and then a disperser solvent along with an extraction solvent is rapidly injected into it. Sorbitol showed the best results and it was more effective on the extraction recoveries of the analytes than inorganic salts such as sodium chloride, potassium chloride, and sodium sulfate. Under the optimum extraction conditions, the method showed low limits of detection and quantification within the ranges of 12-56 and 44-162 pg/mL, respectively. Enrichment factors and extraction recoveries were in the ranges of 2799-3033 and 84-92%, respectively. The method precision was evaluated at a concentration of 10 ng/mL of each analyte, and relative standard deviations were found to be less than 5.9% for intraday (n = 6) and less than 7.8% for interday (n = 4). Finally, some aqueous samples were successfully analyzed using the proposed method and four analytes (diazinon, dimethoate, chlorpyrifos, and phosalone) were determined, some of them at ng/mL level.

Development of graphene-carbon nanotube-coated magnetic nanocomposite as an efficient sorbent for HPLC determination of organophosphorus pesticides in environmental water samples

ABSTRACTA magnetic solid-phase extraction (MSPE) method coupled to high performance liquid chromatography with UV (HPLC-UV) was proposed for the determination of organophosphorus pesticides (OPPs) at trace levels in environmental water samples. The ternary nanocomposite of graphene-carbon nanotube-Fe3O4 (G-CNT-Fe3O4) has been synthesised via a simple solvothermal process and the resultant material was characterised by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. Significant factors that affect the extraction efficiency, such as amount of magnetic nanocomposite, extraction time, ionic strength, solution pH and desorption conditions were carefully investigated. The results demonstrated that the proposed method had a wide dynamic linear range (0.005–200 ng mL−1), good linearity (R2 = 0.9955–0.9996) and low detection limits (1.4–11 pg mL−1). High enrichment factors were achieved ranging from 930 to 1510. The results show that the developed method is suitable for trace level monitoring of OPPs in environmental water samples.

Modified QuEChERS in combination with dispersive liquid-liquid microextraction based on solidification of the floating organic droplet method for the determination of organophosphorus pesticides in milk samples.

In this work, a rapid, environment friendly and sensitive method was established for the extraction and analysis of five organophosphorus pesticides (OPPs) (chlorpyrifos, chlorpyrifos-methyl, isocarbophos, malathion and phorate) in milk samples by means of gas chromatography-flame photometric detection. The pesticides were first extracted with acetonitrile from milk samples by using the modified "quick, easy, cheap, effective, rugged, and safe" (QuEChERS) method. No other clean-up was required after extraction. Then the above-mentioned acetonitrile extract was concentrated by using the dispersive liquid-liquid microextraction combined with solidification of floating organic droplets technique. Several factors that could influence the extraction efficiency, such as type of extraction solvent, disperser solvent, volume of extraction and disperser solvent, salt effect, sample pH, and extraction time, were investigated and optimized. As a result, 15 µL of 1-dodecanol were used as the extractant because of its lower toxicity, 300 µL methanol was chosen as dispersant and the extraction time was set to 1 min. Under the optimized conditions, good linearity was exhibited from 0.01 to 1.0 mg/L with the correlation coefficients higher than 0.9968. The limits of detection of the five OPPs were ranged in 0.1-0.3 μg/L, and the limits of quantification were at the range of 0.3-1.0 μg/L. Moreover, the recoveries of the target analytes from milk samples at spiking levels of 0.01, 0.05 and 0.1 mg/L were between 80.5 and 106.5% with the relative standard deviations varied from 3.6 to 6.3%. This method has been successfully applied to detect OPPs in real milk samples.

Molecularly imprinted calixarene fiber for solid-phase microextraction of four organophosphorous pesticides in fruits

Calixarene was used as a functional monomer to fabricate a molecularly imprinted polymer (MIP) by sol–gel technique for solid-phase microextraction (SPME) of parathion-methyl and its structural analogs. The MIP-coated fiber possessed excellent thermal and chemical stability as well as high extraction capacity. Its selectivity and possible recognition mechanism were investigated. The similarities in molecular shape and functional group play a key role in the selective recognition of the imprinted material. Any changes to the structure of the template would decrease the imprinting factor. A comparison of MIP-SPME was made with liquid–liquid extraction coupled with gas chromatography for the determination of organophosphorus pesticides (OPPs) in fruits. Much lower limits of detection and better recoveries were achieved by SPME in spiked apple and pineapple samples. The experiment demonstrates that the proposed method using the calixarene MIP fiber was more suitable for selective determination of trace OPPs in those fruit samples.

Dynamic microwave-assisted extraction online coupled with single drop microextraction of organophosphorus pesticides in tea samples

A new method for the determination of seven organophosphorus pesticides was developed using dynamic microwave-assisted extraction online coupled with single drop microextraction prior to gas chromatographic mass spectrometry (GC–MS). The method combines the advantages of dynamic microwave-assisted extraction and single-drop microextraction, which could greatly simplify the operation and reduce the whole pretreatment time. In the developed method, tea samples were extracted with 25% ethanol aqueous solution and purified with acidic alumina at the same time, and then the analytes were concentrated into microextraction solvent. When the extraction was completed, the solvent microdrop containing the enriched analytes was retracted into the microsyringe and directly analyzed by GC–MS without any filtration or cleanup step. The method makes extraction, cleanup, separation, and enrichment to be carried out in one step. Several experimental parameters, including type of extraction solvent, type and amount of dispersant, type and volume of microextraction solvent, microwave power, extraction time, and flow rate of extraction solvent were investigated and optimized. Under optimal experimental conditions, good linearity was observed in the range of 2.00–500.00μgkg−1. The limits of detection and quantification were in the range of 0.4–1.7μgkg−1 and 1.1–5.6μgkg−1, respectively. The present method was applied to the analysis of tea samples, and the recoveries of analytes were in the range of 84.9–106.4% with the relative standard deviations ranging from 1.0 to 6.1%. The results showed that the present method was a rapid and feasible method for the determination of organophosphorus pesticides in tea samples.

Chemometric assisted ultrasound leaching-solid phase extraction followed by dispersive-solidification liquid–liquid microextraction for determination of organophosphorus pesticides in soil samples

Ultrasound leaching-solid phase extraction (USL-SPE) followed by dispersive-solidification liquid–liquid microextraction (DSLLME) was developed for preconcentration and determination of organophosphorus pesticides (OPPs) in soil samples prior gas chromatography–mass spectrometry analysis. At first, OPPs were ultrasonically leached from soil samples by using methanol. After centrifugation, the separated methanol was diluted to 50mL with double-distillated water and passed through the C18 SPE cartridge. OPPs were eluted with 1mL acetonitrile. Thus, 1mL acetonitrile extract (disperser solvent) and 10µL 1-undecanol (extraction solvent) were added to 5mL double-distilled water and a DSLLME technique was applied. The variables of interest in the USL-SPE-DSLLME method were optimized with the aid of chemometric approaches. First, in screening experiments, fractional factorial design (FFD) was used for selecting the variables which significantly affected the extraction procedure. Afterwards, the significant variables were optimized using response surface methodology (RSM) based on central composite design (CCD). Under the optimum conditions, the enrichment factors were 6890–8830. The linear range was 0.025–625ngg−1 and limits of detection (LODs) were between 0.012 and 0.2ngg−1. The relative standard deviations (RSDs) were in the range of 4.06–8.9% (n=6). The relative recoveries of OPPs from different soil samples were 85–98%.

N-Octylated Magnetic Nanoparticle-Based Microextraction for the Determination of Organophosphorus Pesticides in Water

A sensitive and simple procedure based on the dispersive solid phase extraction with hydrophobic n-octyl-modified magnetic iron oxide nanoparticles as the sorbent was developed for the determination of ethoprophos, fenchlorphos, parathion methyl, chlorpyrifos, prothiofos, and azinphos methyl in environmental water samples. Dispersive liquid–liquid microextraction was coupled with dispersive solid-phase microextraction to enhance the dispersibility of the selected sorbent and extraction efficiency. The organophosphorus pesticides were detected using gas chromatography with a flame photometric detector. Under optimized conditions, this method achieved low method detection limit (0.02–0.10 microgram per liter), wide linearity (0.5–800 microgram per liter), high enrichment factors (122–143), good correlation coefficients (r = 0.9975–0.9997), and good repeatability (0.2–7.1 percent). This method was also successfully applied to analyze drinking water and surface water with good extraction efficiency (≥82 percent) and high degree of precision (≤5 percent). The results also indicated that the dispersibility of hydrophobic magnetic nanoparticles was enhanced with liquid–liquid microextraction without chemical modification of the magnetic iron oxide nanoparticles.

Surfactant-less water emulsion based dispersive liquid–liquid microextraction for determination of organophosphorus pesticides in aqueous samples

A sample preparation method, surfactant-less water emulsion based dispersive liquid–liquid microextraction coupled with gas chromatography-flame ionization detection, has been developed for the extraction, preconcentration and determination of some organophosphorus pesticides.

Feasibility investigation of hydrogen instead of helium as carrier gas in the determination of five organophosphorus pesticides by gas chromatography-mass spectrometry

Helium is almost the only choosable carrier gas used in gas chromatography-mass spectrometry (GC-MS). A mixed standard solution of five organophosphorus pesticides was analyzed by using GC-MS, and hydrogen or helium as carrier gas, so as to study the feasibility of hydrogen instead of helium as carrier gas for the determination of organophosphorus pesticides. Combining a mass spectrum database built by ourselves, the results were deconvolved and identified by Automated Mass Spectral Deconvolution & Identification System (AMDIS32), a software belonging to the workstation of the instrument. Then, the statistical software, IBM SPSS Statistics 19.0 was used for the clustering analysis of the data. The results indicated that when hydrogen was used as carrier gas, the peaks of the pesticides detected were slightly earlier than those when helium used as carrier gas, but the resolutions of the chromatographic peaks were lower, and the fraction good indices (Frac. Good) were lower, too. When hydrogen was used as carrier gas, the signals of the pesticides were unstable, the measuring accuracies of the pesticides were reduced too, and even more, some compounds were undetectable. Therefore, considering the measuring accuracy, the signal stability, and the safety, etc., hydrogen should be cautiously used as carrier gas in the determination of organophosphorus pesticides by GC-MS.

Ultra-preconcentration and determination of organophosphorus pesticides in soil samples by a combination of ultrasound assisted leaching-solid phase extraction and low-density solvent based dispersive liquid–liquid microextraction

USAL-SPE-LDS-DLLME has been applied for the determination of OPPs in soil samples.

A highly sensitive electrochemical OP biosensor based on electrodeposition of Au–Pd bimetallic nanoparticles onto a functionalized graphene modified glassy carbon electrode

An Au–Pd bimetallic nanoparticle and ionic liquid functionalized graphene–chitosan nanocomposite (Au–Pd/IL-GR–CHI) modified glassy carbon electrode has been developed for the highly sensitive determination of organophosphorus pesticides.

A simple one-step extraction method for the determination of organophosphorus pesticides in shuanghuanglian and antivirus oral liquids by gas chromatography-tandem mass spectrometry

Comparison of oral liquid samples and the extracts: (a) shuanghuanglian oral liquid sample and (b) extracts of shuanghuanglian oral liquid. The GC-MS/MS chromatogram of a blank shuanghuanglian oral liquid sample matrix (c) and a matrix-matched standard mixture of 11 pesticides (d).