Pesticides In Aqueous Samples Research Articles

Nonporous Graphene‐Oxide Coated by Acrylonitrile Polystyrene as New Adsorbent in Dispersed Solid Phase Microextraction for Estimating Pesticides in Aqueous Samples

AbstractGraphene oxide (GO) – acrylonitrile polystyrene (APS) copolymer nanoparticles was synthesized and used for preconcentration and determination of triazole pesticides in an aqueous sample by dispersed solid phase microextraction (DSPME). Graphene oxide was produced using the Hummers method and then coated with acrylonitrile styrene polymer. The synthesized adsorbent was characterized by FT‐IR, XRD, and FE‐SEM analysis. The influence of the effective parameters on the DSPME process was investigated. The results showed that the highest extraction efficiency was obtained by methanol as a desorption solvent, in pH 6, with 20 mg of adsorbent at 20 minutes. At optimum conditions, penconazole, hexaconazole, diniconazole, triticonazole, difenoconazole, tebuconazole were determined by DSPME with GO‐ASP adsorbent in water sample. The linearity ranges were from 10 to 10000 ng ml−1 and the detection limits were varied from 0.31–0.34 ng ml−1. This method was used for estimating triazole pesticides in a river water sample.

Membrane-based inverted liquid–liquid extraction of organochlorine pesticides in aqueous samples: evaluation, merits, and demerits

Membrane-based inverted liquid–liquid extraction of organochlorine pesticides in aqueous samples: evaluation, merits, and demerits

Bursting bubble flow microextraction combined with gas chromatography for determination of organochlorine pesticides in aqueous samples

Bubble-bursting flow microextraction (BBFME) is a simple and powerful microextraction method that conforms to the principles of green analytical chemistry (GAC). This method, combined with GC, is used for extraction, pre-concentration, and determination of some organochlorine pesticides (OCPs) in aqueous samples. In this method, the target analytes are transferred to the surface of the sample solution by the flow of gas bubbles. After the bubbles burst, the analytes disperse into the upper space and are finally collected and extracted. One of the unique properties of gas bubbles is the creation of a two-phase liquid–gas system, whereby the extraction process occurs at the liquid–gas interface where analytes interact with gas molecules in the bubble. In this study, a new method based on the availability of gas bubbles was proposed and investigated. The conditions affecting BBFME performance, including extraction time, the effect of ionic strength, and sample pH were investigated. Under optimal conditions, the dynamic linear range was 0.74–100.0 μg L-1, and the limit of detection and limit of quantification were 0.24–0.33 and 0.74–0.98 μg L-1, respectively. The range of enrichment factor and recovery under optimal conditions was between 228 and 273 and between 82.1 % and 98.2 %, respectively. Finally, using the BBFME method, the toxins simazine, γ-BHC, alachlor, aldrin and dieldrin were successfully extracted from various aqueous samples with satisfactory relative recoveries ranging from 95.3 to 105.1 %.

Development of a solventless method for the pesticides analysis

This paper represents the results of a case study investigating the development of a novel, simple, cost-effective, solventless and sensitive chromatographic method for the determination of volatile pesticides in aqueous samples by an electrothermally prepared pencil graphite (PG). In this study, PG were conditioned by passing a suitable direct current to activate PG by Joule effect. Conditioned PG was used for the extraction of Chlorpyrifos (CP), which is used as case study. The method was also found successful in the determination of CP in real water samples, providing acceptable recovery values (82–111%).

Bursting-bubble flow microextraction combined with gas chromatography to analyze organophosphorus pesticides in aqueous samples.

Bubble-bursting flow microextraction combined with gas chromatography as a green and sustainable microextraction method is used to determine some organophosphorus pesticide residues in water samples. The extraction process occurs at the surface of liquid-gas contact, where the analytes interact with the gas molecules in the bubble. The analytes are transferred to the surface of the sample solution by moving the gas bubbles upwards. The bursting of gas bubbles causes the analytes to disperse in the headspace. Eventually, they are collected for injection into the chromatography system. A one-factor-at-one-time approach was applied to optimize the independent variables in the proposed method. Validation studies were performed according to reliable guidelines. Under optimal conditions, the method indicated a dynamic linear range from 1.0 to 100.0 μg/L. The limit of detection and quantification of the method was 0.29-0.38 and 1.21-1.70 μg/L, respectively. The proposed method was successfully utilized to determine malathion, diazinon, profenofos, and ethion as the target analytes in various water samples with satisfactory relative recoveries ranged from 90.1 to 102.2%.

Rapid Monitoring of Organochlorine Pesticide Residues in Various Fruit Juices and Water Samples Using Fabric Phase Sorptive Extraction and Gas Chromatography-Mass Spectrometry.

Fabric phase sorptive extraction, an innovative integration of solid phase extraction and solid phase microextraction principles, has been combined with gas chromatography-mass spectrometry for the rapid extraction and determination of nineteen organochlorine pesticides in various fruit juices and water samples. FPSE consolidates the advanced features of sol-gel derived extraction sorbents with the rich surface chemistry of cellulose fabric substrate, which could extract the target analytes directly from the complex sample matrices, substantially simplifying the sample preparation operation. Important FPSE parameters, including sorbent chemistry, extraction time, stirring speed, type and volume of back-extraction solvent, and back-extraction time have been optimized. Calibration curves were obtained in a concentration range of 0.1–500 ng/mL. Under optimum conditions, limits of detection were obtained in a range of 0.007–0.032 ng/mL with satisfactory precision (RSD < 6%). The relative recoveries obtained by spiking organochlorine pesticides in water and selected juice samples were in the range of 91.56–99.83%. The sorbent sol-gel poly(ethylene glycol)-poly(propylene glycol)-poly(ethylene glycol) was applied for the extraction and preconcentration of organochlorine pesticides in aqueous and fruit juice samples prior to analysis with gas chromatography-mass spectrometry. The results demonstrated that the present method is simple, rapid, and precise for the determination of organochlorine pesticides in aqueous samples.

Preparation of a novel stir bar coating based on montmorillonite doped polypyrrole/nylon-6 nanocomposite for sorptive extraction of organophosphorous pesticides in aqueous samples

ABSTRACTIn the present work, a novel nanocomposite (NC) was prepared by reinforcing montmorillonite (MMT) into polypyrrole-nylon-6 (PPy-N6) hybrid through in situ oxidative polymerisation of PPy in the MMT-N6 mixture. The prepared novel NC was deposited as a thin layer coating on the stir bar substrate by solvent exchange method. Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction and energy dispersive X-ray spectroscopy were applied to characterise the prepared NCs. The prepared stir bar based on MMT/PPy/N6 NC was applied for sorptive extraction of some organophosphorous pesticides (OPPs) in river water samples with detection by gas chromatography-mass spectrometry (GC-MS). The effect of MMT doping level in the NC and also the effect of PPy hybridation with N6 on the coating extraction capability were studied. Central composite design was used to optimise and study the effects of influencing factors on the stir bar sorptive extraction efficiency such as salt content, pH, extraction time, desorption time, desorption solvent and its volume. The method optimisation step was performed using gas chromatography-flame ionisation detector, while the method validation was conducted using GC-MS. Limits of detection of the developed method are in the range of 0.05–0.3 μg L−1 and the linear dynamic ranges are in the range of 0.3–1000 and 1–1000 μg L−1, respectively. The intra-day precision (RSD %) of developed method with four replicates varied between 5.4 and 8.2% for distilled water spiked at 100 μg L−1. The applicability of the developed method was examined by extraction and determination of OPP compounds in river water samples, indicating the relative recoveries in the range of 80.3–95.3%.

ZnO nanoparticles doped polyamide nanocomposite coated on cellulose paper as a novel sorbent for ultrasound-assisted thin film microextraction of organophosphorous pesticides in aqueous samples

A novel ultrasound assisted-thin film microextraction method based on the application of ZnO NPs/polyamide/cellulose paper was introduced for the determination of OPPs.

Determination of trace polychlorinated biphenyls and organochlorine pesticides in water samples through large‐volume stir bar sorptive extraction method with thermal desorption gas chromatography

A fast and sensitive analytical method based on stir bar sorptive extraction technology with gas chromatography and mass spectrometry was developed to simultaneously analyze 18 kinds of polychlorinated biphenyls and 20 kinds of organochlorine pesticides in aqueous samples. A long adsorption time and small sample volume, which are problems encountered in conventional methods of stir bar sorptive extraction, were effectively solved by simultaneously using multiple stir bars for enrichment with sequential cryofocusing and merged injection. Optimized results showed good linear coefficients in the range of 10-500ng/L and the method detection limits of 0.12-2.07ng/L for polychlorinated biphenyls and organochlorine pesticides. The recovery ratios of the spiked samples at different concentrations were between 64.7 and 111.0%, and their relative standard deviations ranged from 0.9 to 17.6%. Four types of the studied compounds were determined in Qiantang River water samples, and their contents were between 0.82 and 5.00ng/L.

Determination of Three Organochlorine Pesticides in Aqueous Samples by Solid-Phase Extraction Based on Natural Nano Diatomite in Packed Syringe Coupled to Gas Chromatography-Mass Spectrometry.

A rapid, simple, and sensitive technique is proposed based on a miniaturized solid-phase extraction method named mictroextraction in a packed syringe coupled with gas chromatography-mass spectrometry for the preconcentration and determination of three organochlorine pesticides. These include hexachlorobenzene, heptachlor and aldrine in aqueous samples. For the first time, the natural nano diatomite is used a sorbent. Based on this technique, 6.0 mg of the nano sorbent is inserted in a syringe between two polypropylene frits. The analytes would be adsorbed on the solid phase, and would subsequently be eluted using organic solvents. The influence of some important parameters, such as the solution pH, type and volume of the organic desorption solvent, and amount of sorbent on the extraction efficiency of the selected pesticides, is investigated. The proposed method shows good linearity in the range of 0.1 - 40.0 μg L-1, and at low limits of detection in the range of 0.02 - 0.13 μg L-1 using the selected ion-monitoring mode. The reproducibility of this method was found to be in the range of 3.5 - 11.1% for the understudied pesticides. In order to evaluate the matrix effect, the developed method is also applied to the preconcentration and determination of the selected pesticides in different water samples.

Development of Manual Shaking and Ultrasound-Assisted Surfactant-Enhanced Emulsification Microextraction for Analysis of Organophosphorus Pesticides in Aqueous Samples

A novel, rapid and efficient manual shaking and ultrasound-assisted surfactant-enhanced emulsification microextraction (M-UASEME) combined with gas chromatography-flame photometric detection (GC-FPD) was developed for the extraction and determination of eight organophosphorus pesticides (OPPs) in tap water and honey samples. The main parameters that affected the extraction efficiency were investigated and optimized. Under the optimum conditions, the relative standard deviation (RSD, n = 6) ranged from 2.4 to 9.3%. Limits of detection (LOD) were varied between 0.005 and 0.05 µg L-1. Good linearity was obtained in a range of 0.5-50.0 µg L-1 for all analytes with the correlation coefficients (r) > 0.9964. Finally, the developed method was successfully applied to determine the eight pesticide residues in real samples. The recoveries of the target analytes in samples were between 82.4 and 96.7%.

Determination of Organochlorine Pesticides in Aqueous Samples Using Dispersive Liquid-Liquid Microextraction

Background: Organochlorine pesticides (OCPs) have been used worldwide in agriculture because of their low prices and effectiveness against insects. However, their rates of chemical and biological degradation are slow. OCPs are still widely detected in the environment and in organisms. Therefore, it is necessary to develop sensitive and accurate methods to investigate the amounts of OCPs in environmental samples. Objective: We present herein two liquid phase microextraction methods, namely shaker-assisted (SADLLME) and surfactant-assisted dispersive liquidliquid microextraction (SDLLME), for the determination of organochlorine pestcides in water samples. Method: Gas chromatography coupled with an electron capture detector (GC-ECD) was employed. Various factors that affect extraction efficiency, such as the type and volume of the extraction solvent, salt addition, the type and volume of surfactant solution in SDLLME, and the effect of shaking time in SADLLME, have been evaluated. Results: Under the optimized conditions, the enrichment factors ranged from 948 to 2241 for SADLLME and from 695 to 1656 for SDLLME. The linear range was from 7 to 5000 ng L-1 and the limit of detection (LOD) ranged from 1.4 to 3.1 ng L-1 for SADLLME. The linear range was from 5 to 1000 ng L-1 and the limit of detection (LOD) ranged from 1.6 to 2.1 ng L-1 for SDLLME. The absolute recoveries and relative recoveries were 19.849.3% and 80.8110% for river water, 19.647.8% and 76.9116% for lake water, and 15.346.9% and 77.5102% for irrigating water, by SADLLME and SDLLME respectively. Conclusion: These methods, employing minimal amounts of extraction solvent and surfactant solution, could be used to accomplish efficient extraction in 3 min and achieved high enrichment factors. For the analysis of environmental samples, they were both successfully applied to the preconcentration of trace OCPs in water samples. Keywords: Gas chromatography-electron capture detector (GC-ECD), organochlorine pesticides, shaker-assisted dispersive liquidliquid microextraction (SADLLME), surfactant -assisted emulsion dispersive liquidliquid microextraction (SDLLME).

Successive pH- and heat-induced homogenous liquid–liquid extraction

A simple and efficient analytical method known as pH- and heat-induced homogenous liquid-liquid extraction combined with high-performance liquid chromatography has been successfully developed for the extraction and determination of neonicotinoid pesticides in aqueous samples. In this method, a few mL of a water-miscible basic extraction solvent is mixed with a high volume of an aqueous phase containing the analytes and passed through a tube which a portion of the tube is filled with sodium carbonate as a separating agent. By passing the solution, salt is dissolved and the fine droplets of the extraction solvent are formed. The produced droplets go up through the remained solution and collect as a separated layer. In the following, the collected organic phase is removed and placed into a micro tube. Then it is heated in a water bath to form two phases. Several experimental parameters that influence extraction efficiency such as type and volume of extraction solvent, type of phase separation agent, temperature, and extraction time were investigated. Under the optimum conditions, the extraction recoveries and enrichment factors ranged between 51 and 81% and 680 and 1080, respectively. Calibration curves showed a high-level of linearity for all target analytes with coefficients of determination ranging between 0.997 and 0.999. The repeatability of the proposed method expressed as relative standard deviation varied between 3 and 5% (n=6, C=50μgL−1), and the detection limits were in the range of 0.52–1.0μgL−1. Finally, the performance of the method was evaluated by analyzing the selected pesticides in different fruit juice and vegetable samples.

3-D graphene-supported mesoporous SiO2 @Fe3 O4 composites for the analysis of pesticides in aqueous samples by magnetic solid-phase extraction with high-performance liquid chromatography.

Three-dimensional graphene-supported mesoporous silica@Fe3 O4 composites (mSiO2 @Fe3 O4 -G) were prepared by modifying mesoporous SiO2 -coated Fe3 O4 onto hydrophobic graphene nanosheets through a simple adsorption co-condensation method. The obtained composites possess unique properties of large surface area (332.9 m(2) /g), pore volume (0.68 cm(3) /g), highly open pore structure with uniform pore size (31.1 nm), as well as good magnetic separation properties. The adsorbent (mSiO2 @Fe3 O4 -G) was used for the magnetic solid-phase extraction of seven pesticides with benzene rings in different aqueous samples before high-performance liquid chromatography. The main parameters affecting the extraction such as adsorbent amount, volume of elution solvent, time of extraction and desorption, salt effect, oscillation rate were investigated. Under the optimal conditions, this method provided low limits of detection (S/N = 3, 0.525-3.30 μg/L) and good linearity (5.0-1000 μg/L, R(2) > 0.9954). Method validation proved the feasibility of the developed adsorbent, which has a high extraction efficiency and excellent enhancement performance for pesticides in this study. The proposed method was successfully applied to real aqueous samples, and satisfactory recoveries ranging from 77.5 to 113.6% with relative standard deviations within 9.7% were obtained.

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.

Sol-gel/nanoclay composite as a solid-phase microextraction fiber coating for the determination of organophosphorus pesticides in water samples.

A novel solid-phase microextraction (SPME) fiber coated with a sol-gel/nanoclay composite was prepared by the sol-gel technique involving the hydrolysis reaction of alkoxysilanes and the subsequent condensation reaction with hydroxyl groups of the nanoclay on a stainless steel wire. A method based on direct immersion SPME and gas chromatography-corona discharge ion mobility spectrometry was developed for the determination of four organophosphorus pesticides in aqueous samples. The effect of different experimental parameters on the extraction efficiency of the method was investigated. The sol-gel/nanoclay fiber showed higher extraction performance for the organophosphorus pesticides compared with Ppy/nanoclay, sol-gel coating, and three commercial fibers (polydimethylsiloxane (PDMS), PDMS/divinylbenzene (DVB), and polyacrylate (PA)). Limits of detection (LOD) and quantitation (LOQ) of the method were in the range of 0.003-0.012 and 0.01-0.02μgL(-1), respectively. The calibration curves were linear in a concentration range from 0.01 to 2.0μgL(-1) (r (2) > 0.995). The relative standard deviations for intra- and inter-day precision were 3.3-5.6 and 6.4-8.4%, respectively. Fiber-to-fiber reproducibility for three prepared fibers was 7.4-10.2%. Finally, the method was successfully applied for the extraction of the studied compounds from water samples. The relative recovery obtained for the spiked real-water samples were 86-104%.

Development of a field sampling method based on magnetic nanoparticles for the enrichment of pesticides in aqueous samples.

A field sampling method based on magnetic core-shell silica nanoparticles was developed for field sampling and the enrichment of low concentrations of pesticides in aqueous samples. The magnetic nanoparticles could be easily extracted from water samples by a custom-made magnetic nanoparticle collector. The recovery of 15 mg of magnetic particles from a 500 mL water sample was 90.8%. Mixtures of seven pesticides spiked into pure water and pond water were used as marker samples to evaluate the field sampling method. The average recoveries at three levels of spiking were in the range 60.0-104.7% with relative standard deviations <7.1%. The proposed method has good linearity with a correlation coefficient >0.9990 in the concentration range 0.5-15 μg L(-1). The results of the analysis of a sample of poisoned pond water indicate that this method is fast, convenient and efficient for the field sampling and enrichment of pesticides in aqueous samples.

A novel dispersive micro-solid phase extraction method combined with gas chromatography for analysis of organochlorine pesticides in aqueous samples

1D-PANIs have good dispersibility and permeability. A plastic dropper acted as both the extraction and preconcentration device. The proposed method is simple, inexpensive and highly efficient.

Preconcentration of organochlorine pesticides in aqueous samples by dispersive liquid-liquid microextraction based on solidification of floating organic drop after SPE with multiwalled carbon nanotubes

SPE joined with dispersive liquid-liquid microextraction based on solidification of floating organic drop (DLLME-SFO) as a novel technique combined with GC with electron-capture detection has been developed as a preconcentration technique for the determination of organochlorine pesticides (OCPs) in water samples. Aqueous samples were loaded onto multiwalled carbon nanotubes as sorbent. After the elution of the desired compounds from the sorbent by using acetone, the DLLME-SFO technique was performed on the obtained solution. Variables affecting the performance of both steps such as sample solution flow rate, breakthrough volume, type and volume of the elution, type and volume of extraction solvent and salt addition were studied and optimized. The new method provided an ultra enrichment factor (8280-28221) for nine OCPs. The calibration curves were linear in the range of 0.5-1000 ng/L, and the LODs ranged from 0.1-0.39 ng/L. The RSD, for 0.01 μg/L of OCPs, was in the range of 1.39-13.50% (n = 7). The recoveries of method in water samples were 70-113%.

Homogeneous Liquid–Liquid Microextraction Via Flotation Assistance (HLLME-FA) Method for the Pretreatment of Organochlorine Pesticides in Aqueous Samples and Determination by GC–MS

This work proposes a new, rapid and simple homogeneous liquid–liquid microextraction via flotation assistance technique for the analysis of six organochlorine pesticides in water samples. A special extraction cell was used to facilitate collection of the low-density solvent extract. No centrifugation was required in this procedure. Determination was carried using gas chromatography–mass spectrometry. The water sample solution was then added into the extraction cell containing appropriate mixture of extract and homogeneous solvents. In the first step, a homogeneous solution and then with the continuation of water sample injection, a cloudy solution was formed. Using air flotation, the organic solution was collected at the conical part of the designed cell. The optimized levels of effective parameters were found based on response surface methodology approach. Applying the optimized conditions to the system understudy, the limits of detection of all target analytes were obtained in the range of 1.4–7 ng mL−1, while the precisions were found to be in the range of 11.08–14.87 (RSD, n = 3). The linearity of the method lay in the range of 10–150 ng mL−1 with the coefficients of correlation (r 2 ) ranging from 0.998 to 0.999.