Dimethoate Residues Research Articles

Pesticide Residue Analysis from Winter Vegetables Collected from Six Markets of Rajshahi Bangladesh

Pesticide residues in vegetables have become a major concern associated with food safety issues. Five types of winter vegetables like bean, brinjal, tomato, cauliflower and cabbage were collected from six markets of Rajshahi District during January, , 2019 in Bangladesh. Residues of commonly used pesticides (Acephate, Dimethoate, Diazinon, Fenotrothion, Malathion, Chlorpyrifos and Quinalphos) in winter vegetable samples were determined using Gas Chromatography-Flame Thermionic Detector (GC-FTD) procedures. A quick, easy, cheap, effective, rugged and safe (QuEChERS) method with acetate buffering (AOAC Official Method 2007.01) was used for sample preparation. Out of 30 samples, pesticide residues were found only in one brinjal and two tomato samples. The result showed that tomato samples collected from Shaheb bazar and Kharkhari bazar of Rajshahi City contained 0.047 mg/kg and 0.139 mg/kg dimethoate residue, respectively. Brinjal sample collected from Shalbagan bazar, Rajshahi, contained 0.052 mg/kg dimethoate residues. The detected pesticide residue dimethoate of these three samples was higher than maximum residue level (0.01 mg/kg).
 Environ. Sci. & Natural Resources, 12(1&2): 43-50, 2019

Modelling of Health Risk Associated with the Intake of Pesticides from Romanian Fruits and Vegetables

This study is focused on the assessment of risks caused by pesticide residues to Romanian and other European populations, by modelling the acute and chronic risks considering short- and long-term exposures to pesticide residues in specific fruits and vegetables from different Romanian regions. Data were obtained from the Romanian 2016 official monitoring programme. For assessing the dietary risk, we used the Pesticide Residue Intake model—PRIMo. According to the official data, it was found that 50.44% of fruit samples and 28.25% of vegetable samples were contaminated with pesticides. Our study focused on acute risks and chronic risks (in a maximalist worst-case scenario) posed by pesticide residues in strawberries, apples, lettuce and potatoes, given both their high degree of consumption and contamination with pesticides. The short-term exposure assessment of children’s health due to consumption of apples, lettuce and potatoes contaminated with dimethoate, chlorothalonil and carbendazim, revealed exposure levels higher than the acute reference dose (ARfD, as 100%), raising acute risks. On the other hand, the long-term exposure assessment showed that the highest percentage from the acceptable daily intake (ADI, as 100%) was obtained for German children (DE child) (273.9%), followed by Netherlands children (NL child) (143.7%) diets, based on consumption of apples with dimethoate residues. Therefore, serious measures are needed for banning pesticides such as dimethoate, chlorothalonil and carbendazim from all countries in the EU. This would reduce the health risks generated by the consumption of contaminated fruits and vegetables.

Amino-functionalized Al-MIL-53 for dimethoate pesticide removal from wastewater and their intermolecular interactions

Aluminum-organic framework was reformed with various amount of amino-group (Al-(BDC)x(BDC-NH2)1-x, x = 0.00, 0.25, 0.50, 0.75 and 1.00). The technique used to modify the aluminum-based metal-organic framework was the mixed bonding method. All prepared metal-organic frameworks exhibited the same structure as that of Al-MIL-53. The surface areas of amino-functionalized aluminum-based metal-organic framework showed (SBET = 866, 1105, 1260, 1100 and 1060 m2g−1) for Al-BDC, [Al-(BDC) 0.75(BDC-NH2)0.25], [Al-(BDC) 0.5(BDC-NH2)0.5], [Al-(BDC) 0.25(BDC-NH2)0.75] and Al-BDC-NH2, respectively. Amino groups have a great effect on organophosphorus insecticide dimethoate adsorption capability. Pesticide adsorption capacities of Al-BDC, [Al-(BDC) 0.75(BDC-NH2)0.25], [Al-(BDC) 0.5(BDC-NH2)0.5], [Al-(BDC) 0.25(BDC-NH2)0.75] and Al-BDC-NH2 were 154.8, 267.2, 513.4, 344.7 and 266.9 mg g−1, respectively. Fortunately, the results show that Al-(BDC) 0.5(BDC-NH2)0.5 is the best absorbent Al-MOF ratio to reduce dimethoate residue in wastewater. Monte Carlo simulation was used for evaluation of the dimethoate adsorption mechanism.

Dissipation kinetics of dimethoate and malathion residues on tomato-cropped soil

Dissipation kinetics of dimethoate and malathion residues on tomato-cropped soil

Effect of dimethoate in controlling Monolepta hieroglyphica (Motschulsky) and its distribution in maize by drip irrigation.

Monolepta hieroglyphica (Motschulsky) is a primary pest of maize. The effect of dimethoate on controlling a M. hieroglyphica infestation was studied using drip irrigation. Field trials were conducted to determine the most effective application rate and water volume for dimethoate treatment in arid and semi-arid regions. The absorption, distribution and dissipation of dimethoate in maize and soil were examined. Field trials showed that dimethoate at a rate of 2.70 kg a.i. ha-1 and water volume of 200 m3 ha-1 was the most effective treatment for controlling M. hieroglyphica. Dimethoate via drip irrigation showed longer persistence than dimethoate applied via artificial or unmanned air vehicle spraying. Different parts of the maize plant had a hysteresis effect on dimethoate absorption. Dimethoate was absorbed from the roots, transported upward, and enriched in the leaf. Dimethoate was mainly concentrated within a certain range near the emitter after drip irrigation. Terminal residues of dimethoate in maize grain were below detectable levels 42 days after treatment. Dimethoate treatment via drip irrigation can control M. hieroglyphica infestation on maize. Results showed that dimethoate is safe for maize and the environment. This study provides guidance for the application of pesticides in arid and semi-arid areas. © 2019 Society of Chemical Industry.

PESTICIDE RESIDUES IN COW MILK AND DAIRY PRODUCTS FROM THE MAJOR MILK PRODUCING AREA OF SRI LANKA

Nuwara Eliya district is the leading fresh milk producing area in Sri Lanka. In the district, pesticides are widely applied for intensive cultivation of vegetables which leads to contamination of water and material used to feed cows. Contamination and health risk hazards of organophosphorus pesticide residues in milk and dairy products originated in the district were studied. Identification and quantification of eleven commonly used pesticides in 50 milk samples and 12 dairy product samples were performed using standard analytical methods and GC-MS technique. Results revealed that fresh milk contained residues of Prothiofos (0.0568±0.037 mg/kg), Diazinon (0.0378±0.009 mg/kg), Chlorpyrifos (0.0264±0.004 mg/kg), Profenofos (0.196±0.099 mg/kg), Fipronil (0.1906±0.188 mg/kg), Phenthoate (0.1012±0.110mgkg), Dimethoate (0.1196±0.201 mg/kg) and Tebuconazole (0.062±0.069 mg/kg) at higher levels than the recommended maximum residue levels (MRLs) of the World Health Organization. Sterilized milk (0.0115±0.000 mg/kg) and fermented milk (0.022±0.004 mg/kg) contained higher levels of Profenofos than the MRLs. Higher levels of Fipronil than MRLs were observed in pasteurized milk (0.086±0 mg/kg) and fermented milk (0.014±0.000 mg/kg) samples. Phenthoate at higher levels than MRL was reported in pasteurized milk (0.3645±0.402 mg/kg), sterilized milk (0.1405±0.197 mg/kg) and milk powder (0.0055±0.000 mg/kg). Moreover, Dimethoate content in fermented milk (0.087±0.012 mg/kg) was higher than the MRL. Routine monitoring of the above pollutants in food items including fresh milk and value added milk products is essential to prevent, control and reduce the pollution and to minimize the health risks to consumers.

Analysis of pesticide residue in vegetables collected from nine different regions of Bangladesh using Gas Chromatography

The study was conducted to analyze the amount of residue of six commonly used pesticides (e.g. chlorpyriphos, quinalphos, diazinon, acephate, dimethoate and fenitrothion) in vegetables viz., hyacinth bean and eggplant samples collected from local market of nine different locations viz. Cumilla, Bogura, Rangpur, Rajshahi, Khagrachari, Cox’s bazaar, Barishal, Jamalpur and Dhaka for the comparison between the detected residue level with maximum residue limit (MRL) set by European Union. Among 36 analyzed samples of hyacinth bean six samples (16.67%) were contaminated with chlorpyriphos (0.082 mg/kg) and dimethoate residue (0.192 mg/kg - 0.961 mg/kg), all of them were above maximum residue limit. Out of 36 analyzed samples of eggplant 3 samples (8.33%) were contaminated with quinalphos (0.081mg/kg) and dimethoate residue (0.032 mg/kg - 0.217 mg/kg) which were above MRL. Most of the samples contained with dimethoate residue in both the vegetables. The presence of pesticide residue exceeding MRL in vegetables is harmful to human and other living organisms. Analyzed samples of Cumilla, Bogura, Rangpur and Rajshahi showed pesticide residue (i.e. dimethoate, chlorpyriphos and quinalphos) over MRL but the samples of other five locations like Cox’s bazar, Khagrachari, Barishal, Jamalpur and Dhaka did not show any detectable residue which might safe for consumption.
 Asian Australas. J. Food Saf. Secur. 2019, 3(1), 23-26

Surface Enhanced Raman Spectroscopy for In-Field Detection of Pesticides: A Test on Dimethoate Residues in Water and on Olive Leaves.

Dimethoate (DMT) is an organophosphate insecticide commonly used to protect fruit trees and in particular olive trees. Since it is highly water-soluble, its use on olive trees is considered quite safe, because it flows away in the residual water during the oil extraction process. However, its use is strictly regulated, specially on organic cultures. The organic production chain certification is not trivial, since DMT rapidly degrades to omethoate (OMT) and both disappear in about two months. Therefore, simple, sensitive, cost-effective and accurate methods for the determination of dimethoate, possibly suitable for in-field application, can be of great interest. In this work, a quick screening method, possibly useful for organic cultures certification will be presented. DMT and OMT in water and on olive leaves have been detected by surface enhanced Raman spectroscopy (SERS) using portable instrumentations. On leaves, the SERS signals were measured with a reasonably good S/N ratio, allowing us to detect DMT at a concentration up to two orders of magnitude lower than the one usually recommended for in-field treatments. Moreover, detailed information on the DMT distribution on the leaves has been obtained by Raman line- (or area-) scanning experiments.

Assessment of the Levels and Potential Health Risk Posed by Selected Organophosphate Pesticide Residues in Vegetable Farms in Manzini Region, Eswatini

The study investigated qualitatively and quantitatively the presence of organophosphate pesticide (OPP) residues in cabbages, tomatoes and soil from vegetable gardens of Manzini region and assessed the health risk to consumers. Samples were analysed using QuEChERS extraction technique and GC-ECD. Mean recoveries of the pesticides range from 70.61% to 103.76%. Among 26 samples of cabbages analysed, 8 samples (30.77%) contained residues of dichlorvos with a mean concentration of 2.889 ± 0.617 mg/kg, 8 samples (30.77%) contained residues of dimethoate with mean concentration of 2.898 ± 0.894 mg/kg while 5 samples (19.23%) contained both dichlorvos and dimethoate. The highest concentration of dichlorvos of 5.460 ± 0.911 mg/kg was found in Ngwempisi cabbages while the lowest concentration of 0.415 mg/kg was in Mgazini cabbages. The highest amount of dimethoate of 13.150 ± 3.246 mg/kg was in Matfunjwa cabbages while the lowest amount of dimethoate of 0.106 ± 0.187 mg/kg was in Boyane cabbages. All the contaminated cabbages had residue levels above the Codex (FAO/WHO) and EU MRLs. None of the 15 samples of tomatoes was found to be contaminated with organophosphate pesticides. Out of 41 samples of soil, chlorpyrifos was detected in only 3 samples (7.32%) with mean concentration of 1.145 ± 0.136 mg/kg. The highest amount of 2.778 ± 0.134 mg/kg was found in soil from Buoyane. The health risk estimate also demonstrated that the levels of pesticides residues in cabbages pose health threat to consumers. The results of this study provide a database on the levels of organophosphate pesticide residues in vegetables in the Manzini region to the Ministries of Agriculture and Health. This will help introduce safer pesticide management practices. It will also bring awareness to the general public on the dangers of OPPs to human health and environment.

The potentiality of Lysinibacillus sphaericus DM-3 and Bacillus cereus DM-5 in degrading dimethoate

TWO BACTERIAL strains were isolated by soil enrichment technique and identified as Lysinibacillus sphaericus DM-3 and Bacillus cereus DM-5. Biodegradation experiments were performed in carbon free-mineral salt media supplemented with 100 mg/L of dimethoate. The ability of bacterial strains to degrade the dimethoate was evaluated under various conditions such as pH range, temperature and different concentrations of dimethoate. The dimethoate residue was determined quantitatively by HPLC method and the degradation byproducts were identified by GC/MS technique. The results revealed that both bacterial strains can utilize dimethoate as a sole carbon source up to a concentration of 500 mg/L. The optimum temperature for both strains to degrade dimethoate was 28°C. L. sphaericus DM-3 and B. cereus DM-5 showed maximum growth in the presence of dimethoate at pH 6.0 and 7.0, respectively. L. sphaericus DM-3 could degrade 24% of dimethoate within 72 h, whereas the degradation percentage using B. cereus DM-5 was 17% after the same incubation period. The main byproducts from the degradation of dimethoate by L. sphaericus DM-3 and B. cereus DM-5 was namely O,O,S-trimethyl phosphorothioate. This study reports for the first time the efficient ability of L. sphaericus DM-3 and B. cereus DM-5 to degrade dimethoate, up to 500 mg/L, over a wide range of pH.

Persistence and Dissipation Pattern of Dimethoate 30 EC in / on Foxtail Amaranthus and Spinach

A survey was conducted to know the insecticide usage pattern in leafy vegetables and found that dimethoate was the most frequently used insecticide. A field trail was conducted to know the dissipation pattern of dimethoate in foxtail amaranthus and spinach during October - November, 2017. Dimethoate 30 EC was sprayed twice as foliar treatment at 10 days interval @ 200 and 400 g a.i ha-1. The samples were collected from 0, 1, 3, 5, 7, 10, 15 and 20 days after treatment (DAT), extracted by modified QuEChERS method and analyzed by LCMS. The mean initial deposit (1 h after spraying) of dimethoate at 200 and 400 g a.i ha-1 were 7.25 µg g-1 and 19.51 µg g-1 for foxtail amaranthus and 18.37 µg g-1 and 29.46 µg g-1 for spinach, respectively. The residues reached below detectable level of < 0.05 µg g-1 at 10 days after treatment in foxtail amaranthus and 15 and 20 DAT in spinach for both doses. Half-life of dimethoate residues were 0.85 and 0.86 days in foxtail amaranthus; 2.22 and 1.12 days in spinach at 200 and 400 g a.i ha-1, respectively.

Health Risk Assessment on Pesticide Residues in Drinking Water in Shenzhen

Objectives: To conduct health risk assessment of drinking water pesticide residues and its annual trend analysis in Shenzhen City. Methods: The samples of product water, pipe water and secondary supply water from 2011 to 2013 were collected and analyzed. The evaluation models of health risk assessments for children and adults on the 12 non-carcinogenic materials (namely heptachlor, pentachlorophenol, hexachlorocyclohexane, hexachlorobenzene, DDT, malathion, glyphosate, dimethoate, bentazone, atrazine, chlorothalonil, furadan) were recommended by the U.S. Environmental Protection Agency (US EPA). Results: The results showed that the maximums of the measured indicators in the above were controlled in accordance with the National Health Standards (GB5749-2006) published by Ministry of Health in China. The adults and children’s health indices (HIs) of the 12 non-carcinogenic materials were greater than 1 (2.323 - 6.312). Dimethoate residue in factory and peripheral water was the largest risks of harm among the non-carcinogenic pollutants measured. And its HIi (Its Hli) was also greater than 1 (1.995 - 5.094) and followed by hexachlorobenzene and heptachlor. Annual rising trend on health risk of the 12 pesticide residues indicated that their HIT on adults was 2323. 18 × 10-3 in 2011, 2340. 18 × 10-3 in 2012 and 2431. 97 × 10-3 in 2013, and HIT on children was 2965. 07 × 10-3 in 2011, 2986. 77 × 10-3 in 2012 and 3103. 93 × 10-3 in 2013, respectively. This study also suggested that the average risk of peripheral water samples (HIT was equal to 2619. 64 × 10-3) was greater than the factory samples’ (HIT was the same as 2366. 92 × 10-3), and the children’s health risk was greater than the adults’. Conclusions: Health risks of drinking water pesticide residues in Shenzhen have exceeded the threshold values. The dimethoate was the main hazard and had been rising annually, and the children’s health risk was greater than the adults’.

Required Withholding Period for Vine Leaves Following Spraying with Pesticide

Vine leaves are consumed in many countries but little attention is paid to the residues left on them after the application of pesticides that help prevent pests and protect the grapes, the economically important target. Therefore, it is of outmost importance to study the dissipation of the pesticides applied to this crop to protect the consumers that also eat vine leaves. Dissipation kinetics of chlorpyrifos, chlorpyrifos-methyl, diazinon and dimethoate residues were studied in vine leaves grown under sunny conditions in Syria, using an ethyl acetate based sample preparation followed by GC-MS/MS determination. The dissipation rate for all doses applied followed first-order kinetics, with half-lives in grape leaves in the range of 2.9 – 3.9 days. At the recommended application dose, a withholding period of 8.9-37.1 days before consumption should be applied to meet current MRLs and minimise risks to consumers. The effectiveness in the reduction of pesticide loads in vine leaves through washing with either cold or hot water was dependant on the physicochemical properties of the studied pesticides. Hot water washing was very effective for dimethoate, a polar and water-soluble pesticide, with an effective reduction of 92% of the residue level; but no significant effect was observed for chlorpyrifos, the most apolar compound in this study.

Identification of Different Concentrations Pesticide Residues of Dimethoate on Spinach Leaves by Hyperspectral Image Technology

Taking spinach leaves with different concentrations of dimethoate as the research object, the feasibility of identifying spinach leaves containing different concentrations of dimethoate pesticide residues based on hyperspectral imaging and machine learning algorithms was discussed. The band range of hyperspectral images between 900 to 1700mm were scanned by hyperspectral imaging system. The region of interest (ROIs) of the leaves were selected by ENVI and corrected by multiple scatter correction (MSC). The principal component analysis (PCA) was used to analyze the spectral data, and the results showed that the PCA can effectively discriminate spinach samples with different concentrations at the visual level. In addition, the chi-square test feature selection algorithm was combined with support vectors classification (SVC), K nearest neighbor (KNN), random forest algorithm (RF), and linear discriminant analysis (LDA) respectively. The average and standard deviation of the prediction accuracy of the 10-fold cross-validation was chosen as evaluation methods. By comparison, chi-square test combined with LDA was the optimal model and the selected characteristic wavelengths were 1445.8, 1449, 1452.3, 1455.5, 1458.7, 1462, 1465.2 and 1468.4nm. The prediction accuracy and standard deviation of the model were 0.997, 0.008. The results showed that spinach leaves containing different concentrations of dimethoate pesticide residues could be accurately identified based on hyperspectral imaging.

Residue dynamics and risk assessment of dimethoate in sweet potato, purple flowering stalk, Chinese kale, celery, and soil

ABSTRACTResidue dynamics and risk assessment of the insecticide dimethoate applied to sweet potato, purple flowering stalk, Chinese kale, celery were investigated under the climatic conditions of China. The dissipation experiments indicated that the half-lives of dimethoate in purple flowering stalk, Chinese kale, celery, and soil were 5.9–6.5, 3.8–5.1, 3.5–5.4, 3.4–3.6 d, respectively. The terminal residues of dimethoate and omethoate in the vegetables and soil ranged from 0.008 to 1.73 mg kg−1 at preharvest intervals of 3, 5, and 7 d. The results showed risk quotient (RQ) of <1 for sweet potato, Chinese kale, and celery, and of >1 for purple flowering stalk when under the age of 18, indicating that spraying dimethoate on sweet potato, Chinese kale, and celery at the recommended dosage is safe for human consumption, whereas spraying it on purple flowering stalk is associated with some risks to human health.

Evaluation of an alternative fluorinated sorbent for dispersive solid-phase extraction clean-up of the quick, easy, cheap, effective, rugged, and safe method for pesticide residues analysis

In this study, the efficiency of a new fluorinated sorbent for dispersive solid-phase extraction (d-SPE) clean-up in extracts provided by the QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) acetate method from tomato and sweet pepper samples was evaluated by ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC–MS/MS). Clean-up using d-SPE technique has been widely used associated with the QuEChERS method. The most commonly sorbents used in d-SPE are primary secondary amine (PSA), octadecylsilane (C18) and graphitized carbon black (GCB), which are indicated to remove sugars, fatty acids, pigments, among others. The performance of an alternative fluorinated sorbent was compared with PSA and C18 sorbents for representative pesticides and better results were obtained when the fluorinated sorbent was used. Validation presented acceptable results for trueness and precision, with method limit of detection between 0.9 and 1.8μgkg−1 and limit of quantification from 2.6 to 5.4μgkg−1. Most of the compounds presented low matrix effect. Results showed that the fluorinated sorbent contribute to the clean-up of the tomato extract and is an effective alternative, with lower costs and greater efficiency. Commercial tomato samples were analyzed using the proposed method and residues of dimethoate, tetraconazole and thiamethoxam were detected.

Food safety in Thailand 5: the effect of washing pesticide residues found in cabbages and tomatoes

Plant protection products including pesticides are extensively used in worldwide agriculture. In order to protect consumer health, maximum residue limits (MRL) have been established in many countries and by the Codex Alimentarius Commission. In Thailand, the MRL regulation exists but is not fully enforced. Thus, the purpose of this study was to determine pesticide residues in cabbages and tomatoes sold in Thailand and to evaluate if washing vegetables by running water method can remove pesticide residues. 82 cabbage and 100 tomato samples were collected from markets in Bangkok and the metropolitan Bangkok area. They were extracted and quantitatively analyzed for 42 pesticides by GC-MS/MS. Pesticide residues were detected in all of the cabbage samples, representing a rate of pesticide detection of 100%. These samples contained pesticides at levels that exceeded the recommended MRL, denoting a 100% rate of MRL exceedance. Pesticide residues were also detected in all of tomato samples but incidence of MRL exceedance in tomato samples was 82%. Washing cabbages under running water significantly reduced carbofuran residues by 93% and dimethoate residues by 65% (p 0.05) in tomato samples. Therefore, this study has documented evidence of remarkable pesticide residues detected in the cabbage and tomato sold in Thailand. These strongly suggest that Thai government authorities should implement the proper routine monitoring program of pesticide residues in vegetables and fruits. Washing vegetables before consumption is advisable as this considerably reduces the risk of exposure to pesticide residues.

Investigation of degradation and penetration behaviors of dimethoate on and in spinach leaves using in situ SERS and LC-MS

To investigate the degradation and penetration behaviors of the organophosphate insecticide dimethoate applied on spinach leaves, in situ SERS and LC-MS methods were used to detect dimethoate residue on&in spinach leaves picked on different days after treatment (DAT). The SERS and LC-MS methods determined that the dimethoate degradation rate followed first-order kinetics, with a half-life of 3.56 or 4.13days, depending on the respective method. The correlation coefficient of quantification value of these two methods was 0.9562. With the SERS method, we detected most of the penetrated dimethoate in the depth of 60–110μm. With the LC-MS method, we detected dimethoate up to 0.17ng in leaves and that the dimethoate on:in ratio of spinach leaves ranged from 562.25 on 0 DAT to 5.23 on 14 DAT. The combination of these two methods facilitated a better understanding of the behavior and biological fate of pesticides in a complex biological system.

Determination of Organophosphorus Insecticide Residues in Country Bean Collected from Different Markets of Dhaka

The study was conducted to analyze pesticide residues in country bean collected from different areas of Dhaka city from January 2016 to September 2016. A simple and efficient multiple pesticide residue analytical method using Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) extraction technique and Gas Chromatography (GC) coupled with Flame Thermionized Detector (FTD) were used for the determination of pesticide residues in 50 country bean samples. Among the 50 analyzed samples of country bean, 10 samples (20%) contained residues of Dimethoate and Quinalphos, of which 5 samples were above the maximum residue limits (MRLs). Most of the contaminated samples (8 samples) contain residue of Dimethoate. This study reflects the overall scenario of pesticide contamination in vegetables, especially in country bean collected from the local markets of Dhaka city, which will help the consumer to be aware of their health and safety.

Oxidized multiwalled carbon nanotubes decorated with silver nanoparticles for fluorometric detection of dimethoate

A novel method for the detection of dimethoate based on the peroxidase-like activity of silver-nanoparticles-modified oxidized multiwalled carbon nanotubes (AgNPs/oxMWCNTs) has been developed. The synthesized AgNPs/oxMWCNTs showed excellent peroxidease-like catalytic activity in hydrogen peroxide-Amplex red (AR) system (AR is oxidized to resorufinat, with the resorufin fluorescence at 584nm being used to monitor the catalytic activity). After dimethoate was added to AgNPs/oxMWCNTs, the interaction between dimethoate and the AgNPs inhibited the catalytic activity of AgNPs/oxMWCNTs. The decrease in fluorescence was used for the detection of dimethoate in the range of 0.01-0.35μgmL-1 (R2=0.998) with a detection limit of 0.003μgmL-1 (signal/noise=3). This method exhibited good selectivity for the detection of dimethoate even in the presence of high concentration of other pesticides. Consequently, the method was applied to measure the concentration of dimethoate residue in lake water and fruit, thus obtaining satisfactory results.