Gas Chromatography With Electron Capture Detection Research Articles

Development and Validation of an Analytical Method for the Determination of Fipronil and its Degradation Products in 28 Organic and Regular Honey Samples by GC-ECD

Recently, there has been a worldwide problem of increased bee mortality (Colony Collapse Disorder) and the intensive use of pesticides is suspected as one of the causes. Honey samples are one of many indicators to assess bee exposure to pesticides. In this work, a method for the simultaneous analysis of the pesticide Fipronil and its degradation products in honey samples by gas chromatography with electron capture detector (GC-ECD) is presented and validated. The extraction procedure was investigated using C18-SPE with different solvents and methanol showed the best performance. The analytical quantification was performed by internal standard matrix-matched calibration, which resulted in analytical curves presenting correlation coefficients higher than 0.99. The proposed method was validated with good results, such as recoveries around 70 - 99%, limits of detection and quantification bellow 0.014 and 0.072 μg mL-1, respectively, and relative standard deviations below 7%. The method is simple, effective and was successfully applied to 28 commercial honey samples, regular and organic, from different floral sources. The results showed the presence of fipronil desulfinyl, the main degradation product of fipronil, in some samples, even among the organic ones.

RISK ASSESSMENT OF PESTICIDE RESIDUES IN WATER SAMPLES FROM NWANIBA RIVER, AKWA IBOM STATE, NIGERIA

Ecological risk assessment of pesticide residues is not only germane but critical in view of their inherent health challenges and for informed decision-making process. This study was conducted to assess the levels of contamination of organochlorine pesticide residues in water from Nwaniba River in Uruan Local Government Area of Akwa Ibom State. The analysis was carried out using Gas Chromatography with electron capture detector (GC-ECD). The obtained results revealed the predominance of Dieldrin in the different samples of water analysed from Ufak Effiong in the Southern District (station I) and Akani Obio in Uruan Central District (station II) of Uruan. Pesticide levels were found to be significantly higher than the World Health Organization /Food and Agricultural Association (WHO/FAO) Maximum Residue Limits (MRL). The concentrations of organochlorine pesticides (OCPs) ranged from Below detection limit (BDL) - 2.37 × 10-1 ng/µL for water samples. Carcinogenic risk values for γ-BHC, delta-BHC, Dieldrin, Endosulfan I and Heptachlor epoxide in the water samples were found to be less than 1.0 × 10−5, thus posing no potentially serious cancer risk to consumers. The values of cancer risk obtained were lower (6.448 × 10- 11 and 7.208 × 10-11) than the established maximum limit. Hazard index (HI) values calculated for pesticide consumption through water by children and adults are all above unity, indicating that high toxic risks are associated with them. The HI values for children exposure are significantly lower compared to those of adults of Ufak Effiong and Akani Obio. This study reveals that the physicochemical parameters of water obtained from both stations were below the maximum permitted levels set by World Health Organization (WHO) and Nigerian Standard for Drinking Water Quality (NSDWQ). It also provides a baseline data and critical information to encourage effective monitory and management of the ecosystem.

Concentration and Human Health Risk Assessment of Dichlorodiphenyltrichloroethane in Two Species of Fish Muscle from River Gongola Basin and its Dam, Dadinkowa, Gombe State, Nigeria

The concentration of DDT and its metabolites in the two fish species (Clarias gariepinus and Bagrus docmak) from River Gongola basin and its dam, Dadinkowa in Gombe State Nigeria was determined and human health risk association from the consumption of contaminated fish was evaluated. Fish samples were collected for period of six months and the pesticide residues analysis was carried out by using QuEChERS method along with conventional method (Hand shaken technique) and gas chromatography with electron capture detector (GC-ECD). (DDTs) and its metabolites were observed with DDD were the predominant contaminants, followed by DDT. The predominance of DDE may be attributed to their current use in vector control and contamination from past usage. The estimated daily intakes (EDIs) of DDT and its metabolites from all fish species were much lower than the acceptable daily intakes (ADIs), indicating that consumption of fish is at little risk to human health at present. However, the cancer risk estimates in the area of concern and the hazard ratios (HRs) of DDTs below the threshold value of one, indicating daily exposure to these compounds is a potential concern.

Organochlorine pesticides in therapeutic teas and human health risk assessment

ABSTRACT This study evaluated commercially available therapeutic teas for their organochlorine pesticides (OCPs) residue levels to estimate the potential health risks associated with their prolonged consumption. Tea samples that were produced for therapeutic uses were obtained commercially. Organochlorine pesticide residues were extracted from the samples using the modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) method and analysed using Gas Chromatography with Electron Capture Detector (GC-ECD). Results showed that the tea samples contained a large number of OCPs residue at levels that were significantly higher than the maximum residue limits (MRLs) set by the European Union (p > 0.05). Aldrin was detected in all samples, methoxychlor, and p,p’-DDT were detected in ≥88% of the samples while γ–HCH, δ–HCH, endosulfan II, and endosulfan sulphate were detected in ≥69% of the samples. Health risk assessment indicated that the highest risk of cancer was associated with aldrin.

Organochlorine pesticides residue affinity in fish muscle and their public health risks in North West Ethiopia.

Pesticides are the parent compounds, their metabolites, and associated impurities of agricultural and health chemical inputs. If they are found at concentration levels higher than the standard limits, they have potential negative impacts on the ecosystem in general and on fish and humans in particular. This study investigates organochlorine pesticides (OCPs) residue occurrences in fish muscle and assesses their public health potential risks, in North West Ethiopia. The concentration of OCPs residue under gas chromatography with electron capture detector (GC-ECD) was detected in 37.84% of fish muscle samples. The mean amounts detected were Endosalfan I, 341.50 ± 32.19 μg/kg; Endosalfan II, 36.01 ± 2.3μg/kg; Endosalfan sulfate, 5.43 ± 4.06 μg/kg; 4, 4, DDE (4,4-dichlorodiphenyldichloroethylene), 64.01 ± 9.08 μg /kg; 4,4, DDD (4,4-dichlorodiphenyldichloroethane), 5.65 ± 3.12 μg/kg; and 4, 4, DDT (4,4-dichlorodiphenyltrichloroethane), 1.58 ± 0.30 μg/kg. The mean concentration of Endosalfan I tested in fish muscle samples was higher than that of the permissible limit of different international standards. However, due to the low per capita consumption rate of fish origin food in Ethiopia, the health risk index (HRI) ranges from 0.002 to 0.1275, which shows there is no public health risk. This study highlights the possibility of chemical residue occurrence in fish food products, and hence pesticide use regulations and monitoring concentration levels should be implemented regularly to avoid human and environmental health risks.

Underestimation of Anthropogenic Bromoform Released into the Environment?

Bromoform (CHBr3) belongs to very-short-lived substances (VSLSs), which are important precursors of reactive bromine species (BrOx) contributing to tropospheric and stratospheric chemistry. To date, most models calculating bromine product emissions to the atmosphere only consider the natural production of CHBr3 from marine organisms such as macroalgae and phytoplankton. However, CHBr3 has many other anthropogenic sources (coastal industrial sites, desalination and wastewater plants, ballast waters, and seawater toilets) that may drastically increase the amounts emitted in the atmosphere. Here, we report the levels of CHBr3 released in water and air (according to real-time and offline measurements by proton-transfer-reaction time-of-flight mass spectrometry (PTR-ToF-MS) and gas chromatography with electron capture detection (GC-ECD)) in a highly industrialized area where 3 million cubic meters of chlorinated seawater is released each day, which were measured during six field campaigns (at sea and on land) distributed over 3 years. The highest levels found during this survey (which were correlated to the physical-chemical characteristics of the water, meteorological and hydrological conditions, salinity, and temperature gradients along the water column) reached 34.6 μg L-1 in water (100-10 000 times higher than reported natural levels) and 3.9 ppbv in the air (100 times higher than the maximum reported value to date). These findings suggest the need to undertake sampling and analysis campaigns as close as possible to chlorinated discharges, as anthropogenic CHBr3 sources from industrial discharges may be a missing factor in global flux estimates or organic bromine to the atmosphere.

Actual decay of tetrachloroethene (PCE) and trichloroethene (TCE) in a highly contaminated shallow groundwater system

The Quaternary shallow aquifer that served as the subject of research in this work is under the influence of strong anthropopressure manifested by extreme values of contamination with both organic and inorganic substances (max. TOC 1.6 g/l and Cl− 10 g/l) from chemical production. The main attention was paid to the dehalogenation of organochlorine compounds. The research included chlorinated ethane's and chlorinated methane's. In the groundwater samples, the most common components from the group of chlorinated ethenes were determined, i.e. tetrachloroethene (PCE), trichlorethylene (TCE), dichloroethene (DCE) and vinyl chloride (VC) as well as typical components from the group of chlorinated methane's, i.e. tetrachloromethane (PCM), trichloromethane (TCM) and dichloromethane (DCM), were also made. The determinations were made by gas chromatography with electron capture detection (GC-ECD), after liquid-liquid extraction (vinyl chloride: gas chromatography with mass detection (GC-MS), after liquid-liquid extraction).PCE initially undergoes a classical decomposition as a result of dehalogenated reduction to TCE and the Cl− ion (Ai et al., 2019) under aerobic conditions around Eh +100 (+50) to 0 mV. While maintaining the double bond between the carbon atoms, TCE decays under slightly reducing conditions of around Eh -50 to -100 mV to dichloroethene (DCE) and Cl−. Therefore, in the event that the π bond between the carbon atoms is not retained and broken, the TCE breaks down into two functional groups CHCl= and CCl2=. When hydrogen and chlorine are added to the CHCl= functional group, trichloromethane (TCM) is formed, and in the case of two hydrogen atoms it is respectively dichloromethane (DCM). Additionally TCM undergoes a classical decomposition under aerobic conditions by dehalogenation to DCM and the Cl− ion. Chlorine and hydrogen atoms can analogously join the CCl2 = function group to form DCM. Commonly in Quaternary aquifers, often shallow ones, there are favorable conditions for the decomposition of these unstable substances by oxidation, both under the conditions of availability and lack of oxygen (with the presence of e.g. Fe2+ and Mn2+) and immediate, complete mineralization to CO2, H+ and Cl− ions.

Contamination of Foods from Cameroon with Residues of 20 Halogenated Pesticides, and Health Risk of Adult Human Dietary Exposure.

(1) Background: Halogenated pesticides are abundantly used in Cameroon, but there is no information on the health risk of consumers from exposure to their residues in foods. (2) Methods: Residues of 20 halogenated pesticides were determined in 11 agricultural products collected in the 3 largest cities of Cameroon using QuEChERS extraction and gas chromatography with electron capture detector (GC-ECD), and health risk from dietary exposure was assessed. (3) Results: Organochlorines pesticides aldrin, p,p’-dichlorodiphenyl-trichloroethane (DDT) and β-hexachlorocyclohexane (β-HCH) found in 85.0%, 81.9% and 72.5% of samples, respectively, were the most frequently detected. The highest average concentrations of residues were 1.12, 0.74 and 0.39 mg/kg for methoxychlor, alachlor and β-HCH, respectively, found in chilli pepper. Chili pepper (58.9%), cowpea (56.8%), black beans (56.5%) and kidney beans (54.0%) exhibited the highest residue occurrences. Levels above the European Union maximum residue limits (MRLs) were found for all the 20 pesticides, in 40.1% of the positive analyses, and the food samples contained 14 pesticides banned in Cameroon. Chronic, acute, cumulative and carcinogenic risk assessments revealed that lifetime consumption of maize, black beans, kidney beans, groundnuts and chili pepper contaminated with aldrin, dieldrin, endrin, HCB, heptachlor, o,p’-DDT, p,p’-DDD, p,p’-DDT, p,p’-DDE and β-HCH, could pose health risks. (4) Conclusion: These results show that there is an urgent need of pesticide usage regulation, effective application of pesticide bans and management of obsolete pesticide stocks in Cameroon.

DEVELOPMENT OF ANALYTICAL METHOD FOR DETERMINATION OF DITHIOCARBAMATE RESIDUES, EXPRESSED AS CS2 IN FRUITS AND VEGETABLES BY GC-ECD

This report presents the development of analytical method for determination of dithiocarbamat fungicides (DTCs) residues in vegetables through CS2 using gas chromatography with electron capture detector (GC-ECD). Research results show that the method recovery ranges from 84.9 – 98.7% and meets the requirement for pesticide residues analyzing. This method has also been applied for analyzing 12 vegetable samples collected in Tan Dinh and Thi Nghe markets. The results showed that the majority of DTCs levels of these samples are lower LOD value except sample BC2 (0.08 mg/g) and sample X3 (0.11 mg/g).

Determination of the N-Nitroso Compounds in Mouse Following RDX Exposure.

Hexahydro-1,3,5-trinitro-1,3,5-triazine, commonly called RDX, is an important explosive, which is widely used in military and civic activities. As it is used, RDX is widely found in many locations and caused soil and water contamination. Many studies show that RDX is toxic to many organisms, including plants, animals, and microbes. RDX causes genetic toxicity and neurotoxicity as well as potential carcinogenesis. Even it is worse that RDX can be biotransformed into other N-nitroso derivatives, such as MNX, DNX, and TNX; these derivatives can be found in both naturally in RDX-contaminated soil and also in the animal GI tracks. To study the potential effect of RDX and its N-nitroso derivatives, this chapter presents a step-by-step method for detect RDX and its N-nitroso derivatives in animal stomach and GI tracts followed RDX exposure by gas chromatography with electron capture detector (GC/ECD). This method can also be used to detect RDX and its N-nitroso derivatives in other tissues and in other animals and plants.

Organochlorine pesticide analysis in milk by gas-diffusion microextraction with gas chromatography-electron capture detection and confirmation by mass spectrometry

Organochlorine pesticides (OCPs) are synthetic compounds less used nowadays due to their toxicity combined with slow degradation which leads to accumulation in the environment. Gas-diffusion microextraction (GDME) was employed prior to gas chromatography with electron capture detection (GC-ECD) and mass spectrometry (GC-MS). For the first time, the low-cost, eco-friendly GDME system was used to extract the OCPs directly from milk samples and associated with GC-ECD. Parameters that affect GDME's performance (extract volume, extraction time, and temperature) were optimized. The calibration curves of all OCPs (α- and β-hexachlorocyclohexane, lindane, hexachlorobenzene, p,p′-DDE, aldrin, dieldrin, and α-endosulfan) had coefficients of determination (r2) ranging from 0.991 to 0.995, and limits of detection (LODs) values ranging from 3.7 to 4.8 µg L−1. This method also provided satisfactory values for precision with relative standard deviations (RSDs) lower than 10% and recoveries above 90%. As a proof-of-concept, several commercial milk samples were analyzed, aldrin was found in one of them but below the maximum residue limits.

An optimized sample preparation and analysis method for the determination of polycyclic aromatic hydrocarbons and polychlorinated biphenyls in the atmospheric bulk deposition samples

A method based on solid phase extraction (SPE), gas chromatography tandem mass spectrometry (GC-MS/MS) and gas chromatography with electron capture detector (GC-ECD) was developed for the determination of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) in atmospheric deposition samples. Six indicator PCB congeners were analysed by GC-ECD equipped with two micro electron-capture detectors and two gas chromatographic columns, while 12 PAH compounds were analysed by GC-MS/MS. Solid phase extraction on silica sorbent proved suitable for accumulation of PAHs and PCBs from deposited matters. The extraction procedure was based by passing the whole sample volume through a silica cartridge with dichloromethane and n-hexane as the eluting solvents. Two different performances of a bulk collector were compared. The method was validated using field total deposited samples collected monthly over a year by bulk method at an urban background station in Zagreb, Croatia. The levels and occurrence of PCBs corresponded to global environmental pollution, with the deposition rates of ∑6PCBs between 6 - 28 ng m−2 d−1. The deposition rates of ∑12PAHs varied between 132 and 714 ng m−2 d−1 during the warm period, whereas it achieved a significantly higher range of 171 to 1069 ng m−2 d−1 in the cold period.

Dummy-surface molecularly imprinted polymers based on magnetic graphene oxide for selective extraction and quantification of pyrethroids pesticides in fruit juices

A highly binding dummy template molecularly imprinted polymers (Fe3O4-NH2@GO@MIPs) was synthesized used Fe3O4-NH2@GO as carrier by dummy surface molecular imprinting technique (DSMIT) for the first time. Fe3O4-NH2@GO@MIPs were characterized by fourier transform infrared (FT-IR), scanning electron microscope (SEM), transmission electron microscope (TEM), thermogravimetric analysis (TGA), brunauer emmett teller (BET) and vibrating specimen magnetometer (VSM). Adsorption and selectivity experiments of Fe3O4-NH2@GO@MIPs and non-imprinted polymers (Fe3O4-NH2@GO@NIPs) verified that the Fe3O4-NH2@GO@MIPs had a better selectivity and adsorption properties for five pyrethroids pesticides. Adsorption test results revealed that the adsorption behaviors of pyrethroids onto Fe3O4-NH2@GO@MIPs followed Langmuir equation adsorption isotherm and pseudo-second-order kinetic models. Fe3O4-NH2@GO@MIPs were used as sorbent in magnetic solid phase extraction (MSPE) to extract five pyrethroids from fruit juice samples, following desorption with acidified ethyl acetate, the pyrethroids were quantified by gas chromatography with electron capture detection (GC-ECD). The developed method MSPE coupled with GC-ECD achieved satisfactory recovery (72.1–106.8%) with RSD less than 10.8%, and the detection limits (LOD) for fenpropathrin (FENP), lambda-cyhalothrin (LC), cyfluthrin (CYF), fenvalerate (FEN) and deltamethrin (DEL) ranged from 0.007 to 0.015 μg/L. Compared to other methods, the procedure MSPE-GC-ECD based on Fe3O4-NH2@GO@MIPs in this work demonstrated to be a more convenient and practical method for the separation, enrichment, and detection of pyrethroids pesticides from fruit juice samples.

Methylmercury in Predatory and Non-predatory Fish Species Marketed in the Amazon Triple Frontier.

This study assessed if the concentrations of methylmercury (MeHg) in predatory and non-predatory fish caught in the Upper Solimões River are safe for human consumption, according to the reference values established by the Joint FAO/WHO Expert Committee on Food Additives (JECFA). MeHg concentrations were evaluated in muscle of 5 predatory and 4 non-predatory fish species by gas chromatography with electron capture detector (GC-ECD). MeHg concentrations in predatory (0.09mgkg-1) and non-predatory (0.04mgkg-1) fish were under the safe upper limit for human consumption. The general average concentration of MeHg in these fish were 0.05mgkg-1. The Estimated Weekly Intake of MeHg was higher than the provisional tolerable weekly intake in both predatory and non-predatory fish, especially for women. Due to the high rates of fish consumption in the Amazon, the risk assessment based only on the concentration of MeHg in fish may not be accurate.

Levels, Sources and Risk Characterization of Organochlorine Pesticides in Beer Samples from Romania

The present study describes the analysis of nine organochlorine pesticides (OCPs) occurrence in twenty beer samples commercially marketed and widely consumed in Romania. Levels of these compounds were determined by gas chromatography with electron capture detector (GC-ECD). The results indicated that 20% of the examined samples were contaminated with one OCP residues, while 45% of samples have presented multiple pesticides. Among individual compounds, γ-HCH (Lindane) and p,p, DDE were the main contributors to the total OCP residues, suggesting a long-time persistence of these pesticides in soil, recent usage or uncontrolled penetration from some sources. The contamination frequency with the different OCPs of analysed samples was in the following order: DDTs]Driens]Heptachlor]Lindane]HCB. The average lifetime of a daily dose (LADD) for the total compounds under study, were below the acceptable daily intake (ADI) for individual compounds, ranging between 1.41E-07 and 3.13E-06 mg kg bw-1d-1. Also, hazard quotient were presented with very low values (HQ[1), suggesting that, in the analysed samples, the OCP residues represent no threat to human health.

Indoor persistent organic pollutants in agricultural areas from Argentina

Persistent Organic Pollutants (POPs) are anthropogenic chemicals extensively used in the past for industrial and agricultural purposes, characterized by their lipophilicity, ubiquity, volatility and environmental persistence. By other hand, chlorpyrifos is the most widely used current pesticide (CUPs) being the main insecticide used for crops in Argentina. The aim of this work was to assess levels of POPs and CUPs in different fractions of airborne particles collected indoor in agricultural areas from Argentina. Particles higher than 2.5µm were trapped in polyurethane foams (PUF) while particles smaller than 1µm and volatile compounds were adsorbed on activated charcoal. Compounds were analyzed by gas chromatograph with electron capture detector (GC-ECD). Endosulfans, chlordanes, PCBs, and HCHs were detected in all PUF samples, while endosulfans, chlorpyrifos, PCBs, and HCHs were the most abundant in smaller particles. Majority of pesticides showed higher concentrations during the summer season (1397.7 vs 832.5pg/m3 ). Even adding up all measured organic compounds, no sample reaches the threshold limit value for indoor pesticides levels (0.1pg/m3 ), neither in the large or small particle fraction. However, the fact that chronic exposure to POPs has been linked to several diseases raises concern for human health.

A newly modified QuEChERS method for the analysis of organochlorine and organophosphate pesticide residues in fruits and vegetables.

A newly modified QuEChERS method was developed, validated, and tested in-house for the multiclass, multiresidue determination of organophosphate (OPP) and organochlorine pesticide (OCP) residues in fruits and vegetables. The method incorporated a solvent extraction with acetonitrile followed by partitioning with magnesium sulphate (MgSO4) and sodium chloride (NaCl). The final step involved a dispersive solid phase extraction (d-SPE) clean-up prior to gas chromatography with electron capture detection (GC-ECD) analysis. Apples and lettuce were the selected matrices for fruits and vegetables, respectively in the method development stages. Various combinations of sorbents were tested in the clean-up step. Florisil and MgSO4 (FM) d-SPE proved to be the best combination for the clean-up step for both OCPs and OPPs in both the fruit and vegetable matrices. Recovery values fell within the acceptable range of 70 to 120% (RSD ≤20%). The new method is unique as it employs the standard addition calibration technique for the quantification of OCP and OPP residues. Limit of detection, limit of quantification, linearity, recovery analysis, and repeatability were validation parameters used to evaluate the accuracy, precision, and ruggedness of the method. The newly modified QuEChERS method provides a cheaper alternative for the analysis of pesticide residues in fruits and vegetables as samples can be analysed at a fraction of the cost of the original QuEChERS method. The efficacy of the method was tested on several fruits and vegetables from the Central Division of Trinidad and Tobago. OCP and OPP residues were found in 61% of the samples, most of which were above the maximum residue limits.

A Simple and Efficient Optimized Solid-Liquid Extraction with Low Temperature Partition Procedure for Dissipation and Translocation Study of Pesticide Residues in Rice Grains

Pesticides are used globally to protect food against pest attack. This study evaluates the dissipation of bifenthrin and deltamethrin residues in unhulled rice and the translocation of these insecticide residues in husked rice stored at 25 °C in a biochemical oxygen demand (BOD) incubator for 35 days. For pesticide determination, the simple and efficient solid-liquid extraction methods with low temperature partition (SLE/LTP) followed by gas chromatography with electron capture detection (GC-ECD), for unhulled and husked rice were optimized and validated. These methods produced results of validated parameters consistent with Brazilian legislation, showing good efficiency (recovery rate above 95%) and limit of quantification (LOQ) < 0.090 mg kg−1 for bifenthrin and LOQ < 0.070 mg kg−1 for deltamethrin. There was a 40% dissipation of deltamethrin residues after 15 days of storage of the unhulled rice. For the insecticide bifenthrin, dissipation during the 35 days of storage was not verified. The remaining residues of dissipation in the rice grains were below the maximum residue level (MRL) prescribed by the law. The insecticide residues did not translocate in the husked rice grains destined for final consumption.

Residual behavior and risk assessment of butralin in peanut fields.

Butralin is widely used to control single-leaf weeds and some dicotyledons. The application of butralin in the environment may cause residue beyond regulation criteria and residual toxicity. Therefore, it is important to detect and supervise the dissipation behavior of butralin in edible raw food and in the environment. The aim of this study was to monitor butralin in peanuts and soil under farmland conditions and examine the likely dietary risk assessment of butralin for Chinese people on the basis of residual concentrations. A method for the analysis of butralin residue and its dissipation in peanut plants and soil under field conditions was investigated. The results show that an analytical method for the quantization of butralin in peanuts and soil utilizing gas chromatography with electron capture detection (GC-ECD) was developed. Standard recovery experiments using three different butralin spiking levels of 0.01, 0.1, and 1.0mgkg-1 in different samples (i.e., peanut kernels, shell, seedling, stalk, and soil) were conducted. The recoveries of butralin from all matrices ranged from 86 to 108% with relative standard deviations from 3 to 6% (n = 5). The limit of quantification (LOQ) of the method was 0.01mgkg-1. After storage at - 20°C for 365days, the degradation rate of residues of butralin in peanut kernels was less than 30%, which met the storage stability test criteria for pesticide residues in stored commodities of plant origin. The dissipation half-lives of butralin ranged from 4.2 to 6.6days and 4.6 to 6.6days in peanut seedlings and soil, respectively, in farmland ecosystems. At the normal harvest time, the final residue concentrations of butralin in peanuts and soil were all below the LOQ. The final total risk quotient (RQ) values were much lower than RQ = 100%, which indicated that the long-run fitness risk associated with butralin residue in different groups of registered crops is correspondingly low for people in China. The current research results could offer guidance for the rational use of butralin and provide data support for the building of maximum residue limits (MRLs) in China.

Organochlorine pesticide residues in different fishes and shell fishes collected from the flood plains of Sonargaon upazila, Bangladesh

The present study was carried out to assess the concentrations of organochlorine pesticide residues (DDTs; DDE, DDD, 2,4´-DDT and 4,4´-DDT) in natural fishes and prawn species during rainy-season (June-September, 2014) from flood plains of Sonargaon upazila, Bangladesh. The samples were extracted by Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) method and the extracts were cleaned-up by using H2SO4. Analysis of the samples for DDTs residues were carried out by using Gas Chromatograph with Electron Capture Detector (GC-ECD). Controlled fish sample (Cultured Rui fish) was used for the recovery experiments. Percent (%) recovery was found to be in the range of 70%- 113%. The total DDTs contents of the head of different fish and prawn species ranged from 7.53 ± 0.50 ng/g in Jatpunti (P. sophore) to 39.20 ± 3.76 ng/g in Bele (G. giuris) and of the body from 7.55 ± 0.50 ng/g in Jatpunti (P. sophore) to 41.93 ± 3.63 ng/g in Chewa (P. elongatus). While the total DDTs of the total body of seven fish and two prawn species ranged from 4.56 ng/g in Gurachingri (unidentified) to 37.15 ng/g in Chewa (P. elongatus). In the present study, 66.66% samples having value of (DDE + DDD)/DDT, lower than 0.5 ratios indicated the presence of new DDT inputs in the environments of Sonargaon area. The concentrations of total DDTs in all the samples were within the permissible MRL level i.e. for human consumption recommended by FAO-IAEA-WHO. As DDT is a long persistent and bioaccumulative substance in the environment, intake of significant amount of these toxic elements with our diet is a matter of great health concern.&#x0D; Bangladesh J. Zool. 47(1): 137-148, 2019