Pesticides In Soil Samples Research Articles

Hollow fiber liquid-phase microextraction of multiclass pesticides in soil samples: A green analytical approach for challenging environmental monitoring analysis

In the last decades, pesticides have been not well administrated in agriculture causing their presence in environmental compartments, such as soil matrices. Because of that, analytical methods capable to perform the monitoring of such compounds in the environment have become crucial. Therefore, this study reports the development of a hollow fiber liquid-phase microextraction (HF-LPME) with liquid chromatography-mass spectrometry method (LC/MS) for the extraction and detection of 13 multiclass pesticides (carbendazim, diuron, metribuzin, imazapic, carboxy, epoxiconazole, thiabendazole, simazine, carbaryl, cyprodinil pyridaphenthion, quinalphos, and captan) from soil samples. The higher analytical method response was achieved with sample pH 6.0, 30.0 min of extraction time, 1000 rpm as stirring speed, and without salt addition. A linearity of R2 > 0.9800 was achieved, limits of detection, and the limits of quantification values were determined from 66.1 to 198.1 µg/L and 92.7 to 331.2 µg/L, respectively. For intra and inter days assays the values ranged from 0.1 to 10.6 % and 0.5 to 9.3 %, respectively. The method accuracy values ranged from 75.3 to 120.0 %. The developed method obtained recovery values varying from 75.2 to 111.8 %. The present study demonstrated an eco-friendlier alternative for analytical methods for soil samples which was demonstrated by AGREEprep software, showing great potential for the multiresidues evaluation in environmental samples.

Organochlorine pesticides in the urban, suburban, agricultural, and industrial soil in South Korea after three decades of ban: Spatial distribution, sources, time trend, and implicated risks

Organochlorine pesticides in soil samples across urban, suburban, agricultural, and industrial sites were analyzed every year between 2013 and 2016 in South Korea. The study aims to understand the residual status, diminution of occurrence from the South Korean environment, and its risk to humans after three decades of the ban. A general decreasing trend of OCPs has been observed over the years. The OCP concentrations were below the guideline values prescribed for soil pollution. Metabolites like p,p’-DDD and endosulfan sulfate contributed a major portion to the total OCP concentration over the years. The agricultural sites showed higher OCP levels than other site types. Compositional profile and diagnostic ratios suggested that the occurrence of DDT and endosulfan residues were due to historical inputs, but those of HCH and chlordane reflect recent usage in some pockets. The calculated incremental lifetime cancer risk was within the safety limit for all age groups across the genders in the majority of the sites. It is evident that the OCP load on soil is decreasing since the ban on usage. However, regular monitoring with a special focus on metabolites can be an effective control measure to regulate and eliminate the contamination of OCPs.

Design and Testing of an Electrochemical Trace Pesticide Assessment System in Soil Run-Off

Despite recent efforts and breakthroughs in the development of environmental biosensors, one particular vital component of the environment has been probed comparatively much more sparsely-namely, the soil ecosystem that directly and indirectly affects the agricultural health and throughput as well as ecosystem balance. One specific problem that is understudied is the application of pesticides in crops and other plants often finds its way seeping into soil in a large manner and there exists a leaching effect at the soil and ground water sources. This causes long-term effects that is deteriorating for environmental as well as human health- due to soil and ground water contamination that further causes dampening of food production and safety as well as causing acute and chronic diseases in the human body. The potential for a sensor system that detects in-field: the levels of pesticide residue in soil run-off is immense and would be beneficial to understand its negative effect on food security and food safety by inhibiting soil microbial activity and therefore impacting crop throughput and food quality. This field deployable sensor probe would help promote responsible agricultural practices and curb overapplication of harmful agents to the soil. Electrochemistry proves to be a viable choice of application for such a sensor to track pesticides in soil samples due to its feasibility for in-situ analysis used as well as solving for the ASSURED criteria as given by the World Health Organization (WHO), wherein it denotes- Affordable, Sensitive, Specific, User-friendly, Rapid, and robust, Equipment-free and Deliverable to end-users. The proposed system would have to utilize minimally complex sensor modification/functionalization and no pre-processing of samples. Hence citing all these factors and requirements, in this work- we present a highly intuitive electroanalytical sensor approach towards rapid, on-demand screening of 2 commonly used pesticides in this proof-of-feasibility study- Glyphosate and Atrazine in soil run-off which have a half-life of 47 days and 60-75 days respectively. By studying the levels of soil contaminant residues at the field site-the sensor acts as a screening instrument for soil pollution levels. The proposed sensor functions based on affinity biosensing mechanism driven via thiol-crosslinker and antibody receptors that holistically behaves as a recognition immunoassay stack that is specific and sensitive to track test pesticide analytes with a detection limit of 0.19 ng/mL or parts per billion (ppb) range for glyphosate and 0.15 pg/mL or parts per trillion (ppt) range for atrazine. Then, this developed sensor is integrated further to create a pesticide sensing ecosystem by means of a front-end field-deployable smart device with post-hoc Machine Learning (ML) assisted classification (LOW-MID-HIGH levels of pesticide) and thereby, a universal pesticide screening analytical device is designed and fabricated for pesticide assessment in real soil run-off samples. Figure 1

A cartridge-based device for automated analyses of solid matrices by online sample prep-capillary LC-MS/MS.

Sample preparation is an essential step focused on eliminating interfering compounds while pre-concentrating the analytes. However, its multiple steps are laborious, time-consuming, and a source of errors. Currently, automated approaches represent a promising alternative to overcome these drawbacks. Similarly, miniaturisation has been considered an ideal strategy for creating greener analytical workflows. The combination of these concepts is currently highly desired by analytical chemists. However, most automated and miniaturised sample preparation techniques are primarily concerned with liquid samples, while solids are frequently overlooked. We present an approach based on a cartridge packed with solids (soil samples) coupled with a capillary LC-MS, combining sample preparation and analytical steps into a unique platform. As a proof-of-concept, nine pesticides used in sugarcane crops were extracted and analysed by our proposed method. For optimisation, a fractional factorial design (25-1) was performed with the following variables: aqueous dilution of the sample (V1), extraction strength (V2), matrix washing time (V3), extraction flow (V4), and analytical flow (V5). After, the most influential ones (V1, V2, and V3) were taken into a central composite design (23) to select their best values. Under optimised conditions, the method reported linear ranges between 10 and 125ngg-1 with R2 > 0.985. Accuracy and precision were in accordance with the values established by the International Council for Harmonisation (Q2(R1)). Therefore, the proposed approach was effective in extracting and analysing selected pesticides in soil samples. Also, we carried out initial qualitative tests for pesticides in honeybees to see if there is the possibility to apply our method in other solids.

Influence of pesticides on the biological activity of light chestnut soils in South-East Kazakhstan

The paper discusses the impact of pesticides on the biological activity of soils, as well as an environmental assessment of the state of light chestnut soils by the Kazakh Research Institute of Agriculture and Crop Production with the aim to es-tablish diagnostic indicators that reduce biological activity. The study covers physical, chemical and biological properties of soils under crops of winter wheat in the light chestnut soil in the South-East of the Republic of Kazakhstan. The content of pesticides in soil samples was determined using the gas chromatography mass-spectrometric method. The paper shows results of the chromatographic analysis of soil samples regarding the content of pesticides. The study of changes of light chestnut soil biological activity was conducted to determine their relative resistance to pesticide contamination. Data ob-tained revealed the degree of light chestnut soil resistance to pesticide contamination. The study also identified species of soil invertebrates, as well as soil enzymes that should be used as bioindicators for the monitoring of the contamination with pesticides. Results obtained expand knowledge about changes in the biological activity of light chestnut soils due to pesti-cide contamination in the ecosystems of South-East Kazakhstan. In contrast to abundance indicators, the results suggest that the species composition of soil organisms can be used as a criterion for a qualitative assessment of the soil exposure to pesticides.

Analysis of pesticide load on agricultural land and the effect of chemicals on ecosystems

The article analyzes the pesticide load on agricultural land using the example of the agroecosystem of Moscow region, in particular, the concentration of a wide range of pesticides in soil samples at the beginning and end of the growing season of the model crop, the content of pesticides in agricultural crops at the beginning and end of the growing season and residual pesticides in crop products. The research revealed an excess of the concentration of a number of pesticides in soil samples and agricultural crops. It was noted that the concentration of DDT and its analogues in the herbage at the end of the growing season was 0.031 mg/l, that is three times higher than the MPC level.

Multiresidue Method for Analysis of 240 Pesticides in Soils of Tomato Planting by Ultra Performance Liquid Chromatography Coupled to Mass Spectrometry

In this work, an analytical method for the determination of residues for the pesticides-focus was optimized: Azoxystrobin, Boscalide, Carbendazim, Chloranthranilprole, Clothianidin, Diafentiuron, Difenoconazole, Dimetomorfe, Espinetoram, Espinosade A, Espinosade D, Fenurox, Metalaxyl M, Methoxyfenozide, Tiametoxan in soil derived from tomato planting, in order to compare the levels of contamination of these compounds in soil samples. The modified QuEChERS extraction method and Ultra Performance Liquid Chromatography coupled with Sequential Mass Spectrometry were used, with ionization source by Electronebulization in ESI mode (+/-). The method consisted of extracting 15.0 g of soil with 15 ml of saturated calcium hydroxide solution pH 12.3 and 15 ml of acetonitrile, with a consequent partition in the “salting out” effect through 6.0 g of sulfate of anhydrous magnesium and 1.5 g of sodium chloride. The phases were separated by centrifugation at 3700 rpm for 7 min. The extracts were diluted with MeOH licrossolv® grade and injected in a chromatograph. The method was validated based on the parameters of linearity, LOD, LOQ, precision and accuracy. Linearity between 0.2 and 20.0 µg L-1, determination coefficients greater than 0.99. The LOQ values ​​for the method were 13 µg kg-1 for Spinosad and 7.0 µg kg-1 for the other pesticides. The method showed good precision, with RSD values ​​<20%, and accuracy, with recoveries between 70 and 120% for the vast majority of the analyzed compounds. The analytical curves were prepared with reference white soil extracts, in order to minimize the Matrix Effect. The method was considered adequate for the analysis of pesticide residues in soil, since it satisfies the validation parameters of chromatographic methods (European Commission, 2018). After validation, the method was used to analyze the residues of these pesticides in soil samples from conventional, organic and sustainable tomato plantations. Making it possible to compare the levels of environmental impacts generated. In addition to validating the analytical method for the pesticides-focus of the study, it was also possible to validate 240 more compounds, between authorized and unauthorized for use in tomato planting.

Pesticides driven pollution in Kuwait: The first evidence of environmental exposure to pesticides in soils and human health risk assessment

Soil pollution from pesticide residues is a key concern due to the high soil accumulation of pesticides and their human toxicity. Pesticide concentration of surface soil samples from the Sulaibiya agricultural field located in Kuwait was assessed in the present study. The study also investigated health risk assessment for both children and adults based on the residual concentrations. The average concentration of ƩOCPs (sum of organochlorine pesticides) along the present study was 3062 pg/g. The residual concentration of ƩOCPs was comparatively lower as compared to other locations around the world. Out of the 11 observed locations, A, B, and D locations indicated higher concentrations of ƩOCPs. The results indicated that DDT showed higher concentrations 692.87 pg/g in soil samples as compared to the other pesticides. Cancer risks of OCP via ingestion, dermal contact and inhalation of soil particles suggested that all stations were in a safe zone. However, locations A, B and D were closer to the low-risk band. The distribution pattern for each form of organochlorine pesticides (OCP) was different in Sulaibiya, indicating the non-simultaneous use of different groups of OCPs in this region. Multivariate statistical analysis based on cluster analysis identified three classes, 1, 2 and 3 of pesticides, suggesting these are from the same sources. Principle component analysis (PCA) showed that soil physicochemical properties influence the pesticides in soil samples. The results provides the baseline data of pesticides in soils from Kuwait.

A miniaturized spray-assisted fine-droplet-formation-based liquid-phase microextraction method for the simultaneous determination of fenpiclonil, nitrofen and fenoxaprop-ethyl as pesticides in soil samples.

Pesticides are a group of micropollutants that persist for a long time in the environment and pose threats to life. Much effort has been devoted to developing pre-concentration methods capable of producing samples suitable for the detection of pesticides. However, better methods are still required to detect these compounds when they are present in trace concentrations in soils. Spray-assisted fine-droplet-formation-based liquid-phase microextraction was used to prepare soil samples containing three different pesticides, fenpiclonil, nitrofen and fenoxaprop-ethyl, for subsequent analysis by gas chromatography/mass spectrometry (GC/MS). A spraying apparatus was used for the dispersion of the extraction solvent into the sample/standard solution to improve the extraction efficiency. Optimization studies were performed to lower the detection limits of these analytes and the results obtained by the application of the newly developed system were compared with those obtained using the conventional GC/MS method. A calibration curve over the range 5.0-100 μg L-1 was obtained under the optimal conditions. The limits of detection and quantification were 1.56-1.80 μg L-1 and 5.21-5.98 μg L-1 , respectively. The enhancements in detection ability over the conventional method for the three tested pesticides were 188.01, 176.96 and 517.14 for fenpiclonil, nitrofen and fenoxaprop-ethyl, respectively Recovery studies performed in soil samples were satisfactory reflecting accurate applicability of the developed method. The developed microextraction method is a time-saving and simple version of the traditional dispersive liquid-liquid microextraction method that also reduces the use of dispersive solvents.

Nanozyme Sensor Arrays Based on Heteroatom-Doped Graphene for Detecting Pesticides

Pesticides, widely used for pest control and plant growth regulation, have posed a threat to the environment and human health. Conventional methods to analyze pesticide residues are not applied to resource-limited areas because of their high cost, complexity, and requirements for expensive instruments (such as GC/MS and LC/MS). To address these challenges, herein we fabricated colorimetric nanozyme sensor arrays based on heteroatom-doped graphene for detection of aromatic pesticides. The active sites of nanozymes could be differentially masked when different pesticides were adsorbed on the graphene, which in turn resulted in the decrease of their peroxidase-mimicking activities. On the basis of this principle, five pesticides (i.e., lactofen, fluoroxypyr-meptyl, bensulfuron-methyl, fomesafen, and diafenthiuron) from 5 to 500 μM were successfully discriminated by the sensor arrays. In addition, discrimination for different concentrations of each pesticide and different ratios of two mixed pesticides were also demonstrated. The practical application of the sensor arrays was further validated by successfully discriminating the pesticides in soil samples. This work not only provides a facile and cost-effective method to detect pesticides but also makes a positive contribution to food safety and environmental protection.

Comparison of QuEChERS with Traditional Sample Preparation Methods in the Determination of Multiclass Pesticides in Soil.

Background: The increased use of pesticides leads to permanent pollution of soil, and there is a need for continuous monitoring of these agrochemicals in soil. Objective: Three methods for the simultaneous determination of 12 pesticides belonging to eight chemical groups in soil samples were tested and compared based on analytical parameters. Methods: The quick, easy, cheap, effective, rugged, and safe (QuEChERS); traditional solid-liquid extraction (SLE); and Soxhlet extraction were used for soil sample preparation, while detection and quantification of pesticides were performed using gas chromatography-mass spectrometry (GC-MS). Results: The tested methods featured good sensitivity, and with the exception for carbofuran (Soxhlet method, LOD = 29 μg/kg), for the rest of the pesticides, the studied LODs were less than 12 μg/kg. Except for simazine and carbofuran, LODs obtained by Soxhlet extraction were lower than values obtained by other two methods, whereas QuEChERS gave lower LODs than the traditional SLE method for all compounds except atrazine and acetochlor. The recoveries obtained applying QuEChERS, traditional SLE, and Soxhlet methods for multiple analyses of soil samples fortified at 10, 75, and 200 μg/kg of each pesticide were in the ranges 54-103, 40-91, and 12-92%, respectively. Except for chlorothalonil, the highest recoveries were obtained by the QuEChERS method. Soxhlet was better than traditional SLE method for chlorothalonil, heptachlor, and aldrin; organophosphorus pesticides (fenitrothion and diazinon) and trifluralin, gave similar recoveries for both methods. All three methods were proven to be repeatable, with RSDs lower than 19%. Conclusions: Although all tested methods showed as satisfactory regarding most analytical parameters, QuEChERS method showed much better results in terms of confidence, indicating that traditional SLE and Soxhlet extraction still need improvements for determination of multiclass pesticides in soil samples.

Microwave assisted magnetic solid phase extraction using a novel amino-functionalized magnetic framework composite of type Fe3O4-NH2@MIL-101(Cr) for the determination of organochlorine pesticides in soil samples

In this research, microwave assisted magnetic solid phase extraction (MAE-MSPE) coupled with GC-ECD have been successfully used for the determination of eight organochlorine pesticides in soil samples. Specially, the novel Fe3O4-NH2@MIL-101(Cr) composites as the MSPE sorbent played a role of selective enrichment and purification towards the targets. The MAE-MSPE procedure was optimized focusing on microwave extraction temperature and time, solution pH, the amount of sorbent, ultrasonic extraction time, ionic strength, elution solvent type, elution solvent volume, and elution time. The parameters of the analytical method were evaluated. Under the optimal condition, the detection limits of α-HCH, β-HCH, γ-HCH, δ-HCH, p,p′-DDE, p,p′-DDD, o,p′-DDT, and p,p′-DDT were in the range of 0.15–0.28 ng g−1. Satisfactory recoveries were obtained in the range of 71.2–102.4% with the RSDs less than 10.0%. The obtained results demonstrated that the method was suitable for the trace analysis of OCPs. Additionally, molecular docking was employed to calculate the molecular interactions and free binding energies between MIL-101(Cr) and the organochlorines.

Assessment of the soil quality by fuzzy mathematics in farmland around a uranium mill tailing repository in China

Based on statistical analysis of the concentrations of multiple contaminants such as radionuclides, heavy metals and organochlorine pesticides in soil samples, the soil quality of a large piece of farmland around a uranium mill tailing (UMT) pond was assessed by fuzzy mathematics. This study found that the concentrations of U, Th, Cd, Pb and DDT in all sampling sites and Cr in sites 1 and 2 were above the standard values, indicating the effects of the UMTs. We also detected residual OCPs in all soil samples in the study area. The fuzzy mathematics assessment showed that the farmland soil quality around the uranium mill tailing pond at site 1 belongs to class II, while sites 2–6 belong to class I. Based on the above conclusions, in the present study most of the farmland soils were suitable for growing crops except for the areas near the UMT pond (0–500 meters).

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%.

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.

Detection of organophosphorous pesticides in soil samples with multiwalled carbon nanotubes coating SPME fiber.

A headspace solid phase microextraction (HS-SPME) technique using stainless steel fiber coated with 20 μm multi-walled carbon nanotubes (MWCNTs) and gas chromatography with thermionic specific detector (GC-TSD) was developed to determine organophosphorous pesticides (OPPs) in soil. Parameters affecting the extraction efficiency such as extraction time and temperature, ionic strength, the volume of water added to the soil, sample solution volume to headspace volume ratio, desorption time, and desorption temperature were investigated and optimized. Compared to commercial polydimethylsiloxane (PDMS, 7 μm) fiber, the PDMS fiber was better to be corrected as phorate, whereas the MWCNTs fiber gave slightly better results for methyl parathion, chlorpyrifos and parathion. The optimized SPME method was applied to analyze OPPs in spiked soil samples. The limits of detection (LODs, S/N = 3) for the four pesticides were <0.216 ng g(-1), and their calibration curves were all linear (r (2) ≥ 0.9908) in the range from 1 to 200 ng g(-1). The precision (RSD, n = 6) for peak areas was 6.5 %-8.8 %. The recovery of the OPPs spiked real soil samples at 50 and 150 ng g(-1) ranged from 89.7 % to 102.9 % and 94.3 % to 118.1 %, respectively.

A preliminary study of the content and distribution of pesticide residues in soil samples from the Kathmandu valley, Nepal .

The increasing use of pesticides for agricultural production is causing soil pollution problems in different parts of Nepal. Uncontaminated agricultural soils are of great importance as they have a direct impact on food security and human health. The objective of this study was to investigate the quality and quantity of pesticides in soil samples from districts near the capital city of Kathmandu, from where fruit and vegetables are brought to the city for consumption. A questionnaire survey was carried out in four districts around Kathmandu city to investigate the types of pesticides that are most commonly used in these districts. A total of 15 soil samples were taken at a depth of 10 cm and four complete soil profiles were sampled at three different depths (10 cm, 30 cm and 50 cm) on the farms of those who were interviewed. A total of four replicates of each soil sample were extracted and analyzed. The pH, soil texture and organic carbon content of the soil samples were analyzed to understand the general soil characteristics. The QuEChERS method used for the analysis of food samples was modified and applied to the soil samples. An HPLC-MS/MS was used for the qualification and quantification of the pesticide residues in the soil samples. The questionnaire survey revealed that carbendazim, chlorpyrifos-methyl, parathion-methyl, imidacloprid, metalaxyl, dimethoate, omethoate and dichlorvos were the most commonly used pesticides in the area studied. The chemical analysis showed that soil samples from all the districts except Kathmandu city were contaminated with various pesticides. The soil samples collected at the depth of 10 cm were found to be contaminated with the fungicide carbendazim and the insecticide chlorpyrifos-methyl at rates of up to 0.038 mg kg&lt;sup&gt;-1&lt;/sup&gt; and the systemic insecticide imidacloprid was found at up to 0.016 mg kg&lt;sup&gt;-1&lt;/sup&gt;. The study of soil samples taken at different depths (10 cm, 30 cm and 50 cm) showed that pesticides were homogenously distributed with soil depth. The recovery between 77.5-112%, linearity between 0.01 mg kg&lt;sup&gt;-l&lt;/sup&gt; - 2 mg kg&lt;sup&gt;-l&lt;/sup&gt; with correlation factors R2 higher than 0.99 and LOQ between 0.2 µg kg&lt;sup&gt;-1&lt;/sup&gt;- 6.25 µg kg&lt;sup&gt;-l&lt;/sup&gt; were found. Some samples were contaminated with parathion-methyl, a highly carcinogenic organophosphorous insecticide, even though these pesticides had already been banned. For the first time, this study provides information about soil contamination levels due to pesticides in Central Nepal and shows that further research and information campaigns for farmers are necessary.

Simultaneous multi-residue pesticide analysis in soil samples with ultra-high-performance liquid chromatography–tandem mass spectrometry using QuEChERS and pressurised liquid extraction methods

To assess soil contamination, it is important to be able to measure different classes of pesticides simultaneously. For this reason we developed a sensitive ultra-high-performance liquid chromatography–tandem mass spectrometry method for the simultaneous analysis of 25 pesticides in soil samples. Multi-class pesticides (triazines, phenylureas, phenoxy acid pesticides etc.) were analysed using a single mass spectrometry method with a fast polarity switching option, allowing the analysis of 19 compounds in the positive ionisation mode and six compounds in the negative ionisation mode. Extraction of pesticides from soil samples was performed employing a pressurised liquid extraction (PLE) and a quick, easy, cheap, effective, rugged and safe (QuEChERS) procedure, recently developed for the extraction of multi-residue pesticides from food matrices. The extraction efficiency, performance and recoveries of these two procedures were evaluated and compared. In addition, we studied the effect of matrix on signal suppression or enhancement. Isotope-labelled internal standards (ILIS) were used to compensate the suppression or enhancement of signal intensities in the extracted samples. The method was validated using reference soil material (EUROSOIL 7) spiked with 50 μg/kg of each pesticide. The average recovery by PLE varied between 65.1% and 122.2% with RSDs of 1.7–23.4%. QuEChERS provided better recoveries for most of the pesticides, the extraction recovery ranging from 79.4% to 113.3% with RSDs of 1.0–12.2%. Limits of quantification for all target compounds were within a range of 0.1–2.9 µg/kg.

Comparative voltammetric study and determination of carbamate pesticide residues in soil at carbon nanotubes paste electrodes

In this investigation, the persistence of carbamate pesticides in soil samples was investigated. A simple and selective differential pulse adsorptive stripping voltammetry was selected for this investigation. Carbon nanotubes paste electrodes were used as working electrodes for differential pulse adsorptive stripping voltammetry and cyclic voltammetry. A symmetric study of the various operational parameters that affect the stripping response was carried out by differential pulse voltammetry. Peak currents were linear over the concentration range of 10 -5 to 10 -10 M with an accumulation potential of -0.6 V and a 70 s accumulation time with lower detection limits of 1.09x10 -7 M, 1.07×10 -7 M, 1.09×10 -7 M for chlorphropham, thiodicarb, aldicarb. The relative standard deviation (n=10) and correlation coefficient values were 1.15 %, 0.988; 1.13 %, 0.978; and 1.14 %, 0.987, respectively. Universal buffer with pH range 2.0 - 6.0 was used as supporting electrolyte. The solutions with uniform concentration (10 -5 M) were used in all deter

Study of Organochlorinated Pesticide Residues and Polychlorinated Biphenyls in Soil Samples

This paper presents and discusses the data obtained for organochlorinated pesticides and their residues in the soil samples of agricultural areas. Soil contamination is one of most important factors influencing the quality of agricultural products. Usage of heavy farm equipment, the land drainage, an exces­sive application of agrochemicals, emissions originating from mining, metallurgical, and chemical and coal power plants and transport, all generate a number of undesired substances (nitric and sulphur oxides, PAHs, heavy metals, pesticides), which after deposition in soil may influence crop quality. Thus, input of these contaminants into the environment should be carefully monitored. Levels of organochlorinated pesticides contamination were evaluated in agriculture areas that are in use. 10 soil samples were taken in agricultural areas Plane of Dugagjini , Kosovo. Representa­tive soil samples were collected from 0-30 cm top layer of the soil.In the analytical method we combined ultrasonic bath extraction and a Florisil column for samples clean-up. The analysis of the organochlorinated pesticides in soil samples was performed by gas chromatography technique using electron capture detector (GC/ECD). Optima-5 (low/mid polarity, 5% phenyl methyl siloxane 60 m x 0.33 mm x 0.25μm film) capillary column was used for isolation and determination of organochlorinated pesticides. Low concentrations of organochlorinated pesticide and their metabolites were found in the studied samples. The presence of organochlorinated pesticides and their residues is probably resulting of their previous uses for agricultural purposes.