Determination Of Organochlorine Pesticides Research Articles

Water with low concentration of surfactant in dispersed solvent-assisted emulsion dispersive liquid–liquid microextraction for the determination of organochlorine pesticides in aqueous samples

A novel sample preparation method, “water with low concentration of surfactant in dispersed solvent-assisted emulsion dispersive liquid–liquid microextraction (WLSEME)”, coupled with gas chromatography using an electron capture detector (GC-ECD) was developed for the analysis of the organochlorine pesticides (OCPs), heptachlor, α-endosulfan, 4,4-DDE, 2,4-DDD and endrin, in aqueous samples. A microsyringe is used to withdrew and discharge 10–12μL of the extraction solvent and 60–120μL of water as the dispersed solvent (containing 1mgL−1, Tween 80) 4 times within 10s to form a cloudy emulsified solution in the syringe. This is then injected into an 8mL aqueous sample spiked with all above OCPs. Dodecyl acetate and 2-dodecanol were both selected as extraction solvents to optimize their conditions separately. The total extraction time was about 0.5min. Under optimum conditions, using dodecyl acetate (12μL) as extraction solvent, the linear range of the method was 10–1000ngL−1 for all OCPs, and the the limits of detection (LODs) ranged from 1 to 5ngL−1. The absolute recoveries and relative recoveries were from 20.8 to 43.5% and 83.2 to 109.8% for lake water, and 19.9–49.2% and 85.4–115.9% for seawater respectively. In the second method, 2-dodecanol as extraction solvent, the linear range was from 5 to 5000ngL−1 for the target compounds, and the LODs were between 0.5 and 2ngL−1. The absolute recoveries and relative recoveries ranged from 25.7 to 42.2% and 96.3–111.2% for sea water, and 22.4–41.9% and 90.7–107.9% for stream water. This could solve several problems, which commonly occur in ultrasound-assisted emulsification micro-extraction (USAEME), dispersive liquid–liquid micro-extraction (DLLME) and other assisted emulsification methods. These problems include analyte degradation, increased solubility of the extraction solvent and analyte, and high toxicity and large volume of the organic solvent used.

Analytical Method for Determination of Organochlorine Pesticides in Tea Brews using Single-Drop Microextraction with GC-ECD

The single drop microextraction method was developed for the determination of ten organochlorine pesticides in tea brews using gas chromatograph-electron capture detector. The optimized parameters for effective extraction required a 2 μL drop of n-hexane at the tip of a microsyringe immersed in 5 mL of a diluted tea brew sample for 25 min and stirred at 600 rpm. The limit of detection in the range of 0.01 to 0.025 μg/L, with relative standard deviation of repeatability and reproducibility, was in the range of 1–10 and 8–24%. The relationship of the measured signal was a linear function (>0.9863) of concentration and the recovery method ranged from 92–116%. The single drop microextraction method showed the advantage of being easy to operate, low consumption of organic solvent, and high extraction efficiency.

Solvent demulsification-dispersive liquid-liquid microextraction based on solidification of floating organic drop coupled with gas chromatography-mass spectrometry for simultaneous determination of organochlorine pesticides in aqueous samples

A novel method for simultaneous determination of eight organochlorine pesticides in solidification of floating organic drop coupled with gas chromatography-mass spectrometry (GC-MS) was established. A mixture of extractant (n-hexadecane) and dispersive agent (acetone) at the ratio of 1/5 (v/v) was injected into aqueous sample to form an emulsion and an extraction process was accomplished. The demulsifier (750 microL acetone) was then injected to break up the emulsion. The two phases were separated quickly without centrifugation. After being solidified in an ice-bath, the upper layer (n-hexadecane) was transferred into an Eppendorf tube and analyzed by GC-MS after melted at room temperature. Factors affecting extraction efficiency such as the type and volume of extractant, dispersive agent and demulsifier, also ionic strength and pH value of extraction system were studied. Under the optimized conditions, the working curve of the proposed method provided a good linearity in the range of 0.025-2.00 microg/L (r = 0.999 5-0.999 9). The detection limits of the organochlorine pesticides calculated by Hubaux-Vos method were 0.012-0.024 microg/L and the relative standard deviations (RSDs) ranged from 3.15% to 4.53%. The enrichment factors (EF) were 96-101. When the method was applied to the determination of farmland water, the average spiked recoveries were 96.77%-102.93% with the relative standard deviations of 2.68%-4.86%. The proposed method is sensitive and fast. It also has the advantage of little organic solvent consumption so that it is friendly to environment and suitable for batch analysis of organochlorine pesticides in aqueous samples. Meanwhile, it provides technical and methodological support for achieving the automation of sample pretreatment.

Analytical Methodology for the Determination of Organochlorine Pesticides in Vegetation

Analytical Methodology for the Determination of Organochlorine Pesticides in Vegetation

Content Evaluation on Organochlorine Pesticides in Local Vegetables

According to Codex Alimentarius, pesticides are considered as chemicals that prevent, suppress, destroy and repel some pests during manufacture, storage, transport or processing of food, feed and agricultural goods. These chemicals can also be used as plant growth regulator, as defoliant, agent inhibition. The purpose of this study was to evaluate the content of organochlorine pesticides in home-grown vegetables products. The objectives were the establishment of the working matrices and the organochlorine pesticides determination in the matrices chosen by GS method. Due to the high cost of analysis, the vegetable matrix was consisted in 12 sample- lettuce and spinach samples grown in garden and roots samples (carrots, parsley, parsnip and celery) from both home-grown production. Organochlorine pesticide residues were extracted from the sample with acetonitrile and petroleum ether, purified by passage through florisil column and eluted with a mixture of ethyl ether and petroleum ether. Concentrated eluate was subjected to gas chromatographic determination.In all examined samples, there were identified organochlorine pesticide residues with high residual, HCH, DDE, DDT, DDD, endosulfan, and heptachlor, some being above the maximum allowed by European legislation

Preparation of graphene-coated solid-phase microextraction fiber and its application on organochlorine pesticides determination

The coating material determines the sensitivity and selectivity of solid-phase microextraction (SPME). Graphene is predicted to have remarkable properties, such as high thermal conductivity, superior mechanical properties, excellent electronic transport properties and good extraction ability. In this work we immobilized the graphene onto a stainless steel wire to obtain a novel SPME coating based on sol–gel technique. The new fiber possessed a homogeneous, porous surface and showed excellent thermal and solvent stability. Under the optimized conditions, its extraction efficiencies for seven organochlorine pesticides (OCPs) were higher than those of two commercial fibers (PDMS, 85μm; PDMS/DVB, 65μm). Using the self-made sol–gel-graphene SPME fiber, the limits of detections for seven OCPs were found to be ranged from 0.19ngL−1 (o,p-DDT) to 18.3ngL−1 (heptachlor). The repeatabilities for each single fiber were evaluated and the relative standard deviations (RSDs) ranged from 4.7% to 10.6%. The reproducibilities of fiber-to-fiber were 2.3–13.6%. The developed method was successfully applied to the determination of OCPs in rainwater. Hexachlorobenzene (62.7ng/L), trans-chlordance (79.6ng/L) and p,p-DDT (9.30ng/L) were detected. The relative recoveries ranged from 77.7% to 120%.

Preparation and certification of mussel reference material for organochlorine pesticides and polychlorinated biphenyls using isotope dilution-high resolution mass spectrometry

A method for the preparation and certification of the reference material of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in mussel tissue is described. The mussel tissue from Dalian Bay was frozen-dried, comminuted, sieved, homogenized, packaged, and sterilized by 60Co radiation sterilization in turn. The certified values for 18 OCPs and 16 PCBs were determined by high resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS) using isotope dilution and internal standard quantitation techniques. The certified values were validated and given based on seven accredited laboratories, and these values are traceable to the SI (international system of units) through gravimetrically prepared standards of established purity and measurement intercomparisons. The certified values of PCBs and OCPs in mussel span 4 orders of magnitude with a relative uncertainty of about 10%. This material is a natural biological material with confirmed good homogeneity and stability, and it was approved as the grade "primary reference material" (GBW10069) in June 2012 in China. This reference material provided necessary quality control products for our country to implement the Stockholm Treaty on the monitoring of persistent organic pollutants (POPs). The material is intended to be used for the method validation and quality control in the determination of OCPs and PCBs in biota samples.

Analytical Methodology for the Determination of Organochlorine Pesticides in Vegetation

Due to the extensive use of organochlorine pesticides (OCPs) for agricultural purposes and their high persistence and low biodegradability, they have become an important group of contaminants. Detection and quantification of pesticide residues in food, particularly fruits and vegetables, is of growing concern for producers, consumers, and governments. The most widely used pretreatment for the extraction of pesticides in plants is based on solvent extraction liquid-solid extraction (LSE). LSE can be carried out using Soxhlet, shake-flask, homogenization, sonication, and, more recently, microwave-assisted extraction, pressurized liquid extraction, and supercritical fluid extraction. Furthermore, new analytical procedures using the extraction with sorbents, such as solid-phase microextraction, stir bar sorptive extraction, and matrix solid-phase dispersion, have also been used. On the other hand, a wide range of cleanup methods (liquid-liquid extraction, solid-phase extraction, gel permeation chromatography, and dispersive solid-phase extraction; and chromatographic techniques with electron capture detector and mass spectrometry detector; and HPLC with a ultraviolet detector are reported in the literature. This article reviews the applicability, advantages, and disadvantages of various sample preparation techniques (traditional and new techniques) for the analysis of OCPs in different plants and plant materials. It covers more than 15 years of published methods in which pesticide residues have been determined in a wide range of vegetation samples (fruits, horticultural samples, medicinal plants, tree leaves, etc.) by the use of chromatographic techniques after various sample preparation steps. A great number of applications in different plant material are provided. To the best of the authors' knowledge, previously published reviews have not covered as wide and exhaustive range of vegetation matrixes as presented here. A summary of pesticide levels cited in the literature is included.

Application of Magnetic Nanoparticles to Residue Analysis of Organochlorine Pesticides in Water Samples by GC/MS

This paper describes a novel magnetic-SPE method for the determination of organochlorine pesticides (OCPs) in environmental water samples by use of Fe3O4-magnetic nanoparticles (MNPs) coated with oleic acid followed by GC/MS. The chemisorption of oleic acid onto Fe3O4-MNPs provides reusability of the developed sorbent materials several times. The effects of different parameters such as pH, desorption solvent, contact time, temperature, ionic strength, and sorbent dosage on the efficiency of magnetic-SPE were investigated. The optimized SPE method involved shaking 50 mL of water sample (pH 4) with 50 mg oleic acid coated Fe3O4(-) MNPs for 1 h, isolating the sorbent with an Nd-Fe-B magnet, and eluting the OCPs with methanol. An ionic strength of 0.1 M and temperature of 15 degrees C provided the maximum extraction efficiency. The LOQs were in the range of 0.006 to 0.048 microg/L. For three fortification levels, recoveries were in the range of 44-108%, with RSD <5%. The developed SPE method was successfully applied to real water samples, and it is viable, rapid, and easy to use for analysis of OCPs in water samples.

Determination of Organochlorine Pesticides in Saussurea Costus by Ultrasonic Extraction and Solid-Phase Microextraction Method

Ultrasonic extraction and purification using solid-phase microextraction column for the determination of 7 types of organochlorine pesticides including α, β, γ, δ-BHC, 2,4 '-DDT, 4,4'-DDT and heptachlor from the Saussrrea cotus were investigated in this study. The pretreatment of Saussrrea cotus samples, the effect of different ultrasonic time on the extraction efficiency and the effect of different ratio of dichloromethane: petroleum ether on purification efficiency were studied. Results show that the satisfactory extraction conditions for pre-treatment process are: 30 minutes ultrasonic treatment; the volume ratio of dichloromethane and petroleum ether mixture is 3:7.

Determination of organochlorine pesticides in agricultural soils applyng Quechers, C-ECD and GC-MS/MS

The organochlorine pesticides (OCPs), due the wide use in agriculture until about 30 years (except the most recent bans by the EU for lindane, methoxychlor and endosulfan) and their chemical stability and slow biodegradation became ubiquitous pollutants. Most OCPs are persistent organic pollutants that have long life cycles in the environment and being transported for long distances. The residues of pesticides in soil can be absorbed by plants, entering the food chain, leading to bioaccumulation. The objective of this study was to determine the presence of 14 OCPs (HCH (α, β, ζ), HCB, lindane, aldrin, α-endosulfan, dieldrin, p, p'-DDE, endrin, endosulfan β-p-p' -DDD, o-p'-DDT and methoxychlor) in soils of 5 Portuguese regions. The extraction was performed with QuEChERS, analysis by GC-ECD and confirmation by GC-MS/MS. One sample showed a residue above the LOQ, revealing contamination by dieldrin at a concentration of 45.36 µg .kg-1.

Application of ultrasound-assisted emulsification microextraction based on applying low-density organic solvent for the determination of organochlorine pesticides in water samples

In this study, a polyethylene Pasteur pipette-based ultrasound-assisted emulsification microextraction (USAEME) applying low-density organic solvent was successfully developed for the extraction of trace levels of organochlorine pesticides (OCPs) in water samples and followed by gas chromatography–mass spectrometry (GC–MS) analysis. In this approach, a polyethylene Pasteur squeeze-type pipette was employed as a convenient extraction device and ultrasound radiation was applied to accelerate the emulsification of low-density organic solvent in aqueous solutions to enhance the microextraction efficiency of OCPs in water samples. Thirty microliters of extraction solvent (isooctane), of lower density than water, were injected into the aqueous sample solution held in the pipette. The latter was then immersed in an ultrasound water bath to form an emulsion. After 30s extraction, phase separation was achieved by centrifugation. The upper layer (isooctane) was collected and analyzed by GC–MS. No disperser solvent was required in this procedure. Significantly, fast analysis and high extraction efficiency were achieved. Another feature of the procedure was the use of the pipette as the extraction device, which permitted less dense than water organic solvent to be used as extraction solvent. This method broadens the applicability of USAEME to a wider range of solvent. Additionally, carry-over problems were avoided with the use of the disposable pipette. Parameters affecting the efficiency of polyethylene Pasteur pipette-based USAEME, such as the extraction solvent, extraction solvent volume, extraction and centrifugation time, ionic strength and extraction temperature were investigated. Under the optimum conditions, the proposed method provided good enrichment factors (EFs) in the range of 128 and 328, with relative standard deviations (RSDs) ranging from 2.7% to 12.4%. The limits of detection were in the range of 0.8 and 10ng/L depending on the analytes. The linearities were between 0.01 and 50μg/L for hexachlorobenzene, dieldrin, endrin and o,p′-DDD, 0.05–25μg/L for heptachlor, and 0.005–50μg/L for p,p′-DDE. Finally, the polyethylene Pasteur pipette-based USAEME was successfully used for the fast determination of OCPs in river and tap water samples. The proposed method provides a simple, convenient, rapid, sensitive, cost-effective, and environmentally friendly process for the determination of OCPs in water samples.

Selected ion storage versus tandem MS/MS for organochlorine pesticides determination in drinking waters with SPME and GC-MS

The use of two modes for mass spectrometry (MS) detection with an ion trap instrument, selected ion storage (SIS) and tandem mass spectrometry (MS/MS), are compared for the solid-phase microextraction (SPME)–gas chromatography (GC) coupled to mass spectrometry (GC-MS) determination of 16 priority organochlorine pesticides (OCPs) in drinking water samples at the ultratrace levels (ng L−1) required by official guidelines in the European legislation. Experimental parameters investigated for the SPME sample preparation were: the type of coating (100 µm polydimethylsiloxane, PDMS, and 65 µm poly(dimethylsiloxane)–divinylbenzene, PDMS/DVB), SPME modality, extraction and desorption times and desorption temperature and the methanol percentage in the SPME working solution. Under the calculated optimal conditions two methodologies were developed, one for SIS and the other for MS/MS modes. The detection limits, precision and accuracy were evaluated for both alternatives and were appropriate to the official guidelines requirements. The SPME–GC-MS(SIS) methodology offered LODs from 0.2–6.6 ng L−1, precision below 13% and recoveries between 83 and 110%. The SPME–GC–MS/MS methodology provided limits of detection (LODs) ranging from 0.3 to 7.6 ng L−1, % RSD were ≤14% and recoveries of 79–108% were achieved. After the results observed within an Interlaboratory Exercise, the latest MS methodology was selected for the pursued analysis in real drinking water samples. Also, the good results in this round-robin exercise validate the proposed SPME–GC–MS/MS methodology.

A Comparative Study of the Ionization Modes in GC–MS Multi-residue Method for the Determination of Organochlorine Pesticides and Polychlorinated Biphenyls in Crayfish

A gas chromatography–mass spectrometry (GC–MS) multi-residue method with different ionization modes has been developed for the determination of 23 organochlorine pesticides and ten polychlorinated biphenyls (PCBs) in crayfish. The approach was based on an extraction with acetonitrile saturated by hexane (containing 0.1 % acetic acid), followed by a dispersed solid-phase extraction cleanup with primary secondary amine and octadecylsilane, and finally analyzed by GC–MS/MS operated in electron impact (EI) and positive chemical ionization (PCI), and GC–MS in negative chemical ionization (NCI), respectively. An isotope internal standard, DDT-D8, was used for quantification. These three GC–MS procedures were validated and compared using crayfish samples fortified at three levels (5, 10 and 20 ng/g). Good linearity, accuracy, precision and sensitivity were achieved by all three ionization modes with recoveries in the range of 70 to 112 %, relative standard deviations (RSDs) below 10 % and limits of detection (LODs) in the range of 0.002 to 8 ng/g. Extremely high selectivity was obtained by both EI- and PCI-MS/MS, while PCI was more sensitive to compounds containing nitro and carbonyl groups, and EI was a better choice for dieldrin, endosulfan, and its metabolites. NCI-MS had the highest sensitivity but lower anti-interference ability and was not suitable for the determination of DDTs and PCBs. These three ionization modes can be used as complementary and alternative in routine GC–MS analysis of organochlorine pesticides and polychlorinated biphenyls in food.

An investigation on the sorption behaviour of montmorillonite for selected organochlorine pesticides from water

The sorption behaviour of montmorillonite towards organochlorine pesticides (OCPs) from aqueous solutions is reported. After preliminary investigation of the sorption capability of clay for selected OCPs, aldrin was used as a model compound for further experiments. The batch sorption experiments were carried out as functions of contact time, pH of the solution, initial aldrin concentration and dosage of the montmorillonite. After traditional liquid–liquid extraction, the determination of OCPs was carried out by gas chromatography coupled with a μ-electron capture detector (GC-μECD). The results indicated that sorption of aldrin followed the second-order kinetic model and that the equilibrium time depended on the initial aldrin concentration. The film diffusion was found to be a main sorption rate control mechanism. The removal was explained according to the electrostatic bonding mechanism. The Freundlich isotherm model better represented the sorption data than the Langmuir model. The montmorillonite was also used efficiently for the removal of OCPs from fortified tap and surface (lake) water samples.

The development and optimization of a modified single-drop microextraction method for organochlorine pesticides determination by gas chromatography-tandem mass spectrometry

We have developed a new method for single-drop microextraction (SDME) for the preconcentration of organochlorine pesticides (OCP) from complex matrices. It is based on the use of a silicone ring at the tip of the syringe. A 5 μL drop of n-hexane is applied to an aqueous extract containing the OCP and found to be adequate to preconcentrate the OCPs prior to analysis by GC in combination with tandem mass spectrometry. Fourteen OCP were determined using this technique in combination with programmable temperature vaporization. It is shown to have many advantages over traditional split/splitless injection. The effects of kind of organic solvent, exposure time, agitation and organic drop volume were optimized. Relative recoveries range from 59 to 117 %, with repeatabilities of <15 % (coefficient of variation) were achieved. The limits of detection range from 0.002 to 0.150 μg kg−1. The method was applied to the preconcentration of OCPs in fresh strawberry, strawberry jam, and soil. A representative figure for OCP analysis by a modified SDME method.

Analysis of Organochlorine Pesticides in Soil Using Optimized FMAE-GC/MS

A focused microwave-assisted extraction (FMAE) was optimized and coupled to gas chromatography–mass spectrometry for the determination of organochlorine pesticides in soil samples. According to the result, the combination of 20 min extraction time at 48 °C and a mixture of 1+1 of n-hexane-acetone as extraction solvent is the best conditions. The recovery values is 72.8%～96.4% in the above conditions. The relative standard deviation was 4.39%~13.18%. We have good recovery values when spiked 20ng, 40ng and 60ng standard into 5.00g soil sample.

Automated Sample Clean-up and Fraction of Organochlorine Pesticides in Sediments Using the SPE–GPC–VAP System

This paper describes an automated sample clean-up and fraction method using the SPE-GPC-VAP system for the determination of organochlorine pesticides (OCPs) in sediments. The method is based on a simultaneous extraction/clean-up step to reduce analysis time and solvent consumption. The parameters of a solid-phase extraction procedure, a gel permeation chromatography procedure and an AccuVap procedure were optimized to obtain maximum recovery of the target analytes with minimum presence of matrix-interfering compounds. The detection limits ranged from 0.03 to 0.13 ng g(-1) and the recovery ranged from 50.05% to 104.39%. The relative standard deviation was lower than 19.34% when OCPs concentrations in sediments ranged from 1.25 to 125 ng g(-1).

Determination of organochlorine pesticides and polychlorinated biphenyls in post-mortem human lung by matrix solid-phase dispersion with the aid of response surface methodology and desirability function

A matrix solid-phase dispersion (MSPD) method for the simultaneous determination of 20 organochlorine pesticides (OCPs) (aldrin, endrin, dieldrin, α-BHC, β-BHC, γ-BHC, δ-BHC, α-chlordane, γ-chlordane, p,p′-DDE, p,p′-DDT, p,p′-DDD, endosulfan I, endosulfan II, endosulfan sulfate, endrin aldehyde, heptachlor, heptachlor epoxide, endrin ketone and methoxychlor) and six polychlorinated biphenyl (PCB) congeners (PCB 28, 52, 101, 138, 153 and 180) in post-mortem human lung has been developed and validated. Response surface methodology (RSM) and desirability function were employed to optimize the extraction conditions of MSPD. Extraction was carried out using Florisil (2.0g) as the sorbent material as well as clean-up adsorbent (1.5401g), n-hexane:dichloromethane (11:89, v/v) as the eluting solvent (15.45mL) and Na2SO4 (2.0g) as dehydrating agent. Determination and quantification of OCPs and PCBs residues were carried out using a gas chromatograph equipped with an electron capture detector (GC-ECD). A mass spectrometric detector (GC–MS) in the selected ion monitoring (SIM) mode was also used for confirmation purposes. Method detection limits by GC–MS ranged from 0.42 to 0.87ngg−1 and 0.51 to 1.35ngg−1, for OCPs and PCBs, respectively. Lower detection limits were calculated for GC-ECD ranging between 0.15–0.30ngg−1 and 0.18–0.48ngg−1, respectively. Relative standard deviations did not exceed 9%. Analytes provided recoveries ranging from 65% to 106%. The proposed method was successfully applied to the analysis of lung tissues from six autopsy cases.

GCMS Determination of Organochlorine Pesticides (OCPs) in Fish from River Cauvery and Veeranam Lake

Organochlorine Pesticides (OCPs) were analyzed using Gas Chromatography-Mass Spectrometer (Selective Ion Monitoring mode) in the muscle tissues of five fish species such asO. mossambicus, L. parsia, E. suretensis, C. striata and S. wynaadensisfrom seven locations of River Cauvery and one location in Veeranam Lake. OCPs viz., DDTs, HCHs, CHLs, cyclodienes, heptachlor, HCB and mirex were detected with varying concentrations among species and locations. Mirex which was not reported in the fish tissues elsewhere reported in this study. The study on the risk associated with the consumption of fish species that had higher concentrations of aldrin, dieldrin and mirex showed significant carcinogenic risk to the human beings.