Quantification Of Pesticide Residues Research Articles

Quantification of pesticide residues in milk by HPLC-UV analysis in Gilan province, Iran

ABSTRACT Eighty milk samples, comprising raw cow’s milk, pasteurised milk, ultra-high temperature milk, and camel milk, were collected randomly from supply centres from December 2022 to March 2023 in Gilan province, Iran. Aldrin, diazinon, and dichlorodiphenyltrichloroethane (DDT) were determined using high-performance liquid chromatography. Aldrin and diazinon were observed in all samples. Furthermore, 87.5% of the milk samples were contaminated with DDT. The raw milk sample showed the greatest concentration of aldrin, measuring 9.31 ± 0.80 µg L−1, and there was no significant difference with the camel milk. The samples of camel milk, raw milk, and ultra-high temperature milk demonstrated the greatest levels of DDT, whereas the lowest concentration was detected in pasteurised milk. In all samples, the maximum residue level (MRL) of Codex Alimentarius and the national Iran standard (20 µg L−1 for DDT) was only exceeded by 25.1% of the milk samples.

High pesticide exposure and risk to bees in pollinator plantings adjacent to conventionally managed blueberry fields

Wildflower plantings adjacent to agricultural fields provide diverse floral resources and nesting sites for wild bees. However, their proximity to pest control activities in the crop may result in pesticide exposure if pesticides drift into pollinator plantings. To quantify pesticide residues in pollinator plantings, we sampled flowers and soil from pollinator plantings and compared them to samples from unenhanced field margins and crop row middles. At conventionally managed farms, flowers from pollinator plantings had similar exposure profiles to those from unenhanced field margins or crop row middles, with multiple pesticides and high and similar risk quotient (RQ) values (with pollinator planting RQ: 3.9; without pollinator planting RQ: 4.0). Whereas samples from unsprayed sites had significantly lower risk (RQ: 0.005). Soil samples had overall low risk to bees. Additionally, we placed bumble bee colonies (Bombus impatiens) in field margins of crop fields with and without pollinator plantings and measured residues in bee-collected pollen. Pesticide exposure was similar in pollen from sites with or without pollinator plantings, and risk was generally high (with pollinator planting RQ: 0.5; without pollinator planting RQ: 1.1) and not significant between the two field types. Risk was lower at sites where there was no pesticide activity (RQ: 0.3), but again there was no significant difference between management types. The insecticide phosmet, which is used on blueberry farms for control of Drosophila suzukii, accounted for the majority of elevated risk. Additionally, analysis of pollen collected by bumble bees found no significant difference in floral species richness between sites with or without pollinator plantings. Our results suggest that pollinator plantings do not reduce pesticide risk and do not increase pollen diversity collected by B. impatiens, further highlighting the need to reduce exposure through enhanced IPM adoption, drift mitigation, and removal of attractive flowering weeds prior to insecticide applications.

Advances in sample preparation methods for pesticide residue analysis in medicinal plants: A focus on Nepal.

Medicinal plant safety is a rising challenge worldwide due to the continued overuse of pesticides to their maximum residue limits. Due to the high demand for medicinal plants, their production is being increased and sometimes protected by pesticide use. The analysis of these residues requires robust analytical methods to ensure the safety and quality of medicinal plants. Developing effective sample preparation for detecting pesticides is challenging, due to their diverse natures, classes, and physico-chemical characteristics. Hence, existing techniques and strategies are needed to improve the reliability of the results. The review discusses the current state of sample preparation techniques, analytical methods, and instrumental technologies employed in pesticide residue analysis in medicinal plants. It highlights the challenges, limitations, and advancements in the field, providing insights into the analytical strategies used to detect and quantify pesticide residues. Reliable, accessible, affordable, and high-resolution analytical procedures are essential to ensure that pesticide levels in medicinal plants are effectively regulated. By understanding the complexities of pesticide residue analysis in medicinal plants, this review article aims to support the conservation of medicinal plant resources, promote public health, and contribute to the development of sustainable strategies for ensuring the safety and quality of medicinal plants in Nepal. The findings of this review will benefit researchers, policymakers, and stakeholders involved in the conservation of medicinal plant resources and the promotion of public health.

Comprehensive multiresidue chromatographic methods for monitoring pesticides in agricultural areas and corresponding plant protection zones

This article reports a comprehensive analytical method for the identification and quantification of a broad range of pesticides in green plant crops. The sample preparation method for pesticides involved an optimization of the QuEChERS-based extraction protocol, with sample mass, volume of added water, and the type of cleanup sorbent as variables. A sorbent combination based on ENVI-Carb and ChloroFiltr was examined. A highly efficient method was developed for the purification of plant extracts with 900 mg MgSO4, 150 mg PSA, and 15 mg ENVI-Carb at the d-SPE stage, combined with gas chromatography and liquid tandem mass spectrometry for the determination of 197 pesticides in crop plants containing chlorophyll. The method was validated in accordance with the requirements of international guidelines SANTE/11312/2021. The method was applied to quantify pesticide residues in 29 pairs of green crop plants and plants from the corresponding crop protection zone to verify whether the zones are effective barriers to prevent pesticides from penetrating outside agricultural areas. The number and types of agrochemical preparations were chosen by farmers. In total, more than 60 one- and several-component pesticide formulations were applied to the crops included in the study. The pesticide residues were detected in 21 crop samples and 3 samples from protection zones. Epoxiconazole, an active substance that was banned for use in 2021, was found in a spring barley sample. Based on the conducted research, the effectiveness of the protection zones has been clearly demonstrated, and it has been proven that environmental migration of pesticides and unauthorized agricultural practices pose a risk to ecosystems.

Multiresidue analysis and dietary intake risk assessment of 29 pesticides in banana from five provinces of southern China

The present study utilized a combined quick, easy, cheap, effective, rugged, safe (QuEChERS) method with ultra-performance liquid chromatography/tandem mass spectrometry (UPLC-MS/MS) and gas chromatography-tandem mass spectrometry (GC-MS/MS) to detect and quantify pesticide residues in both whole banana fruit and pulp samples collected from five provinces in southern China between June 2018 and December 2021. The analysis identified the occurrence of 29 widely used insecticides, fungicides, and herbicides on bananas, including organophosphates, organochlorines, pyrethroids, triazoles, etc. The limits of quantification for the pesticides analyzed in the banana matrix ranged from 1.0 to 5.0 μg/kg. Among the 501 samples collected, the detection rates of pesticides in whole fruit and pulp samples were 65.1 % and 40.9 %, respectively. Specifically, 20 kinds of pesticides were detected in whole fruit samples, while 16 were detected in pulp samples. Furthermore, imidacloprid was detected across various regions and years. The evaluation of risk of hazard quotient (HQ) to the identified pesticides in whole fruit and pulp samples revealed values ranging from 0.0016-0.0313 and 0.0002–0.0131, respectively. Overall, the results suggest that the detected pesticide residues in bananas are unlikely to pose an unacceptable health risk to consumers of different age groups in China.

Pesticide residues detected in Colossoma macropomum by the modified QuEChERS and GC-MS/MS methods

This study aimed to detect pesticides in the muscle tissue of farmed tambaqui (Colossoma macropomum), in relation to good management practices (GMP) and prophylaxis and biosecurity measures. There were 54 fish farms randomly selected from the 138 found in the Microregion of Zona da Mata, RO - Brazil, for visits and collection of epidemiological data. There were extracted 24 muscle fragments were extracted from dorsolateral portion of the tail of five specimens tambaqui per fish farming. The methods of detection and quantification of pesticide residues were modified QuEChERS and GC-MS/MS. Most fish farms are small businesses and their production areas are smaller than a rural module. These ventures are an income alternative for rural producers, this information is confirmed in percentage of 88.89% (48/54) of the rural properties visited have livestock and agriculture as their main productive activity. Water monitoring was carried out in 70.37% of fish farms. However, with frequency of two water analyzes per year. Preventive and prophylactic measures taken were performed in 30% (17/54). In addition, 7% (4/54) of fish farmers reported using sodium chloride and/or using formalin as a secondary preventive measure. It is also important to mention that there was a report of administration of potassium permanganate in a fish farm, 2% (1/54). There were 12.49% (3/54) positive for at least one pesticide. The chemical compounds found Azosxystrobin (<LOQ), Epoxiconazole (<LOQ) and Chlorpyrifos (<LOQ). The presence of Azosxystrobin, Epoxiconazol and Chlorpyrifos in tambaqui muscle tissue samples was detected above acceptable limits by the PNCRC.

Monitoring and method validation of organophosphorus/organochlorine pesticide residues in vegetables and fruits by gas chromatography.

In this study, an analytical method was developed and validated for the assessment of pesticide residues in commonly consumed vegetables and fruits. Fresh samples of apple, green peas, tomatoes, and cucumbers were processed and subjected to analysis using a modified QuEChERS (quick, easy, cheap, effective, rugged, safe) extraction technique. Subsequently, quantification of pesticide residues was conducted utilizing gas chromatography (GC)-electron capture detector. Extraction and cleanup parameters were meticulously optimized, resulting in a modification of the original QuEChERS method. This modification aimed to reduce solvent consumption, making the study more environmentally friendly. The developed method was validated in terms of selectivity, specificity, linearity, precision, and accuracy by following the SANTE guidelines. Calibration curves showed good linearity (r > 0.99) within the test range. Precision was evaluated by intra- and inter-day experiments with an acceptable relative standard deviation (<20.0%). Recovery was assessed at the limit of quantification level and was observed to fall within the range of 70%-120%, with relative standard deviations below 5.45%. The validated method presented here can be applied to analyze pesticide residues in various other vegetables, fruits, and cereals. It is essential for ongoing monitoring of pesticide residues to ensure public safety.

Cobalt ferrite/semiconducting single-walled carbon nanotubes based field-effect transistor for determination of carbamate pesticides

Carbaryl and carbofuran are the carbamate pesticides which have been widely used worldwide to control insects in crops and house. If the pesticides entered in to the food products and drinking water, they could cause serious health effects in humans. Therefore, the development of a rapid, simple, sensitive and selective analytical device for on-site detection of carbamates is crucial to evaluate food and environmental samples. Recently, semiconducting single-walled carbon nanotube-based field effect transistors (s-SWCNT/FETs) have shown several advantages such as high carrier mobility, good on/off ratio, quasi ballistic electron transport, label-free detection and real-time response. Herein, cobalt ferrite (CFO) nanoparticles decorated s-SWCNTs have been prepared and used to bridge the source and drain electrodes. As-prepared CFO/s-SWCNT/FET had been used for the non-enzymatic detection of carbaryl and carbofuran. When used as a sensing platform, the CFO/s-SWCNT hybrid film exhibited high sensitivity, and selectivity with a wide linear range of detection from 10 to 100 fMand the lowest limit of detections for carbaryl (0.11 fM) and carbofuran (0.07 fM) were estimated. This sensor was also used to detect carbaryl in tomato and cabbage samples, which confirmed its practical acceptance. Such performance may be attributed to the oxidation of carbamates by potent catalytic activity of CFO, which led to the changes in the charge transfer reaction on the s-SWCNTs/FET conduction channel. This work presents a novel CFO/s-SWCNT based sensing system which could be used to quantify pesticide residues in food samples.

Detection and quantification of pesticide residues in tomatoes sold in urban markets of Ouagadougou, Burkina Faso

Introduction“What people worry about, and what makes them sick and kills them, are not the same” is maxim for risk communication experts. In Burkina Faso, pesticides are used by vegetable producers to improve productivity. However, consumer concern over pesticide use is high. Of course, if over-used pesticides could have serious health consequences for producers and consumers and also cause ecological damage.MethodsA cross-sectional survey was conducted to detect and quantify the levels of residues of pesticides in tomatoes sold in urban markets of Ouagadougou. Two samples were collected from each vendor (n = 328 vendors) making a total of 656 tomato samples from 26 markets. Samples were subjected to High-Performance Liquid Chromatography (HPLC) for detection and quantification of six pesticide residues commonly used in West Africa including acetamiprid, chlorpyrifos, lambda-cyhalothrin, deltamethrin, dichlorodiphenyltrichloroethane (DDT), and permethrin.ResultsOverall, 62.2% of tomato samples contained at least one pesticide residue including acetamiprid, chlorpyrifos, lambda-cyhalothrin and DDT. Deltamethrin and permethrin were however not detected in any samples. The highest proportions of samples were contaminated with DDT (32.9, 95%CI: 27.9–38.3%), followed by acetamiprid (31.1, 95%CI: 26.2–36.5%), lambda-cyhalothrin (28.4, 95%CI: 23.6–33.6%) and chlorpyrifos (10.7, 95%CI, 7.6–14.6%). 21.3% of samples exceeded Codex Alimentarius Commission (CAC) Maximum Residue Levels (MRLs) including Acetamiprid (13.1%), DDT (7.3%), lambda-cyhalothrin (2.1%) and chlorpyrifos (0.3%); while 61.3% of sample exceeded European Union (EU) MRLs. Multiple pesticide residues (up to 4) were detected simultaneously in 27.7% of the total samples.ConclusionThe study suggests that producers and consumers may be exposed to pesticides that can be highly toxic to them and to the environment. We recommend further quantitative risk assessment for consumer exposure and identification of best procedures to reduce residues in vegetables. Meanwhile, monitoring and regulating pesticide use, with the promotion of good agricultural practices, are warranted to prevent consumers, producers and environmental exposure. However, given this may not be effective, promotion of consumer washing and peeling of vegetables may be warranted to at least empower consumers to protect themselves. Moreover, where resources are scarce they should be directed to the highest burden hazards and in Burkina Faso, these are not likely to be pesticides.

A Comprehensive Review of Pesticide Residues in Peppers

Pesticides are chemicals that are used to control pests such as insects, fungi, and weeds. Pesticide residues can remain on crops after application. Peppers are popular and versatile foods that are valued for their flavor, nutrition, and medicinal properties. The consumption of raw or fresh peppers (bell and chili) can have important health benefits due to their high levels of vitamins, minerals, and antioxidants. Therefore, it is crucial to consider factors such as pesticide use and preparation methods to fully realize these benefits. Ensuring that the levels of pesticide residues in peppers are not harmful to human health requires rigorous and continuous monitoring. Several analytical methods, such as gas chromatography (GC), liquid chromatography (LC), mass spectrometry (MS), infrared spectroscopy (IR), ultraviolet-visible spectroscopy (UV-Vis), and nuclear magnetic resonance spectroscopy (NMR), can detect and quantify pesticide residues in peppers. The choice of analytical method depends on the specific pesticide, that is being tested for and the type of sample being analyzed. The sample preparation method usually involves several processes. This includes extraction, which is used to separate the pesticides from the pepper matrix, and cleanup, which removes any interfering substances that could affect the accuracy of the analysis. Regulatory agencies or food safety organizations typically monitor pesticide residues in peppers by stipulating maximum residue limits (MRLs). Herein, we discuss various sample preparation, cleanup, and analytical techniques, as well as the dissipation patterns and application of monitoring strategies for analyzing pesticides in peppers to help safeguard against potential human health risks. From the authors' perspective, several challenges and limitations exist in the analytical approach to monitoring pesticide residues in peppers. These include the complexity of the matrix, the limited sensitivity of some analytical methods, cost and time, a lack of standard methods, and limited sample size. Furthermore, developing new analytical methods, using machine learning and artificial intelligence, promoting sustainable and organic growing practices, improving sample preparation methods, and increasing standardization could assist efficiently in analyzing pesticide residues in peppers.

Screening and quantification of pesticide residues in ciders by liquid chromatography-high resolution mass spectrometry

The present study aimed to apply a multi-residue method for the screening and quantification of pesticide residues in ciders, low alcoholic beverages made by fermentation of apple juice. Twenty bottled craft cider samples purchased from the Czech market were analysed for pesticide residues. The residues of pesticides were extracted from samples using the QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) procedure in combination with additional solid-phase extraction (SPE) sample clean-up to achieve the lowest detection limit possible. In this study, targeted screening of pesticide residues in the samples was performed with the Q-Orbitrap mass spectrometry instrument. We identified 18 pesticides in cider samples analysed by screening method using an accurate-mass database of about 500 pesticide compounds, including their retention times, empirical formulas, and characteristic fragments. Additionally, liquid chromatography with high-resolution tandem mass spectrometer (LC-HRMS/MS) was used for re-analysis of positive findings of pesticides in samples and allowed to quantify compounds of interest at 0.2 µg L–1 concentration level. The monitoring scheme was applied to the set of craft ciders, and the results revealed the presence of pesticide residues in most of the samples at trace levels ranging from 0.5 to 5 µg L–1 and rarely at a level higher than 10 µg L–1.

Searching for What You Can’t See - Evaluation of Pesticide Residues in Grain Sold at Selected Markets of Southwest Nigeria

Studies on the use of pesticides in southwest Nigeria have revealed a substantial rise in a variety of pesticide-related illnesses, including mental impairment and reproductive problems. Those who work in agriculture and are regularly exposed to pesticides are the most impacted. The World Health Organization (WHO) predicts that three million severe pesticide poisoning episodes occur globally each year, with at least 300.000 deaths and 99% of cases occurring in low- and middle-income nations. The effects of longer-term exposure to pesticides on health are not yet precisely estimated. Objectives: To this end, the objective of this study is to assess the knowledge of pesticide residues and common pesticides in grain-based food (brown and white beans, yellow and white maize, brown millet and rice) about pesticide use in selected markets of Southwest Nigeria. Methods: A total of 240 respondents were selected from four states (Ado-Ekiti, Ibadan, Osun and Ondo) with the aid of structured questionnaire and interview guide using purposive sampling technique. The markets were Oja-titun (market) Ile-Ife, Osun; Alesinloye Market Ibadan, Oyo; Oja Oba, Ado-Ekiti, Ekiti; and Oja Oba, Akure Ondo State. The identification and quantification of pesticide residues was done using a Varian 3800/4000 gas chromatograph mass spectrometer while 60 structured questionnaires were administered to respondents including food merchants, buyers/consumers as well as food vendors. Data were analysed using descriptive statistics. Results: The experiment was conducted from November 2020 to November 2021. Up to 50.4% never read instructions on pesticide application while a shared 24.8% read them always and occasionally. The number of respondents who never read the instructions were particularly high in Ekiti and Ondo, up to 52.5% of the respondents in Ekiti do not know whether or not they are exposed to pesticides during application. Also, majority of the respondents never attended any professional training on pesticide application, this amounted to 79.3%. Most people were not aware that unsafe pesticide application is harmful to human health. Similarly, a wide variety of symptoms were reported by respondents following pesticide application or consumption of grains, these included headaches and dizziness, itching and redness of the eyes, skin allergy, diarrhea, and stomach disorder, vomiting and loss of appetite, weakness of the body, asthma, permanent skin patches, shortness of breath, excessive sweating. Millet recorded the highest number of OCP residues while maize had the lowest. On the contrary, maize had the highest number of OPP and carbamate residues while millet had the lowest number of OPP residues. Meanwhile, maize, rice and beans had only one carbamate pesticide residue. Conclusions: According to the study's conclusions, farmers who can only get information from agricultural extension officials should receive urgent and immediate attention for raising awareness. Additionally, extensive IPM training programs must be created with the intention of disseminating precautions for protecting human health and a healthy agro-ecosystem. In order to find more effective pest management methods that utilize less pesticides, it is crucial to reevaluate the pesticide residues and common pesticides found in grains in the targeted markets. To reduce farmers' exposure to pesticides, it is also required to establish personal protective measures, special educational initiatives, and legislation promoting the use of safer pesticides. Significance and novelty: This study gives policymakers a comprehensive understanding of the ways that may be utilized to close the significant knowledge gap on pesticide residues in grains and provides an insight into the knowledge of pesticide residues and common pesticides in grains.

Ecological risk assessment of pesticides in sediments of Pampean streams, Argentina

After their application in agricultural areas, pesticides are dispersed throughout the environment, causing contamination problems. In Argentina, the main promoter of transgenic biotechnology in the region, the total consumption of agrochemicals has increased significantly in recent years. Most chemicals dumped near surface waters eventually end up in bottom sediments and can be toxic to the organisms that live there. However, published data on the mixing of pesticides in this compartment is still scarce. The objective of this work was to detect and quantify pesticide residues in the sediment of rural streams in the Pampas region and to carry out acute and chronic risk assessment in these aquatic ecosystems. The study area comprises the mountainous system of Tandilia, located in one of the most productive agricultural areas in the country. The concentration of atrazine, acetochlor, chlorpyrifos, cypermethrin, and 2,4-D in the sediment of four rural streams was determined in three different seasons, and the toxic units (TU) and the risk ratios (RQ) were calculated. All the compounds analyzed were detected in most of the sampling seasons and study sites, at concentrations higher than those established in the national and international quality guidelines for the protection of aquatic biota in surface waters and for human consumption. Chlorpyrifos, cypermethrin, and acetochlor were the main pesticides contributing to the TU and RQ values, representing a medium or high ecological risk in most of the sites. Therefore, the evaluation of these pesticides in the bottom sediments could be a decisive factor in assessing the risk to the aquatic environment.

Multiple pesticide residue determination in major vegetables purchased from Gazipur district of Bangladesh

The present study was initiated to detect and quantify pesticide residues in three selected major vegetables (hyacinth bean, cauliflower and yard long bean) collected from 5 local markets of Gazipur district of Bangladesh. The vegetable samples were prepared by Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) extraction technique and analyzed by Gas Chromatography (GC) equipped with Flame Thermionic Detector (FTD). In this study, 45 vegetable samples were analyzed. Out of 15 samples of hyacinth bean, 2 samples (13% of the total samples) contained pesticide residues above MRL and the remaining samples did not contain any detectable pesticide residues. In the instance of cauliflower, 2 samples (13% of the total number of samples) contained pesticide residues above MRL, while the remaining samples had no detectable pesticide residues. Pesticide residues with levels exceeding MRL were found and measured in 3 samples (20% of the total number of samples) from 15 yard long bean samples. From remnant samples, no pesticide residue was detected. This study depicts the overall scenario of pesticide contamination in vegetables specially in hyacinth bean, cauliflower and yard long bean available in the local markets of Gazipur city, Bangladesh. As a result, it is important to intensify routine pesticide residue monitoring in commercially cultivated vegetables. Asian Australas. J. Food Saf. Secur. 2022, 6 (2), 57-64

Evaluating sulfoxaflor residues in pig tissues using animal modeling.

Maximum residue limits (MRL) for pesticides in feed have been set to protect public health and produce safe livestock products. In vivo experiments to establish MRL are essential, as livestock are commonly used to obtain reliable In vivo quantitative information. Here, we aimed to evaluate whether small laboratory animals can replace or reduce monogastric livestock in experiments to quantify pesticide residues In vivo after oral consumption through feed. First, 24 pigs and rats were randomly assigned to four groups and fed 0, 3, 9, or 30 mg/kg of sulfoxaflor. After four weeks, serum, muscle, fat, liver, kidney, and small intestine samples were collected, and sulfoxaflor residues were analyzed using liquid chromatography – tandem mass spectrometry. Sulfoxaflor residues in pig tissues were significantly correlated with those in rat tissues. Model equations were formulated based on the residual sulfoxaflor amount in pig and rat tissues. The calculated and measured sulfoxaflor residues in pigs and rats showed more than 90% similarity. Sulfoxaflor did not affect body weight gain, feed intake, or the feed conversion ratio. Therefore, we concluded that pesticide residue quantification in vivo to establish MRL could be performed using small laboratory animals instead of livestock animals. This would contribute to obtaining In vivo pesticide residue information and reducing large-scale livestock animal experiments.

Determination of pesticides and their degradation products in sediment samples by accelerated solvent extraction and solid-phase extraction with high-performance liquid chromatography-high-resolution mass spectrometry.

A new sensitive and selective methods was developed to quantify different types of pesticides and their degradation products in sediment. The method developed was optimized and modified based on the accelerated solvent extraction, followed by the solid-phase extraction clean-up technique. High-performance liquid chromatography coupled with mass spectrometry was used for analysis. The influence of various parameters on the extraction process was investigated, including the extraction temperature, extraction solvent, purification column and purification solvent, etc. Under the optimal conditions, the relative recoveries of the pesticides and their degradation products ranged from 80 to 106% for spiked blank sediment and environmental sediment samples with relative standard deviations of 1-9%. The method displayed low method detection limits for both sediment matrices and achieved good linearity over the tested range of concentrations. The physical and chemical properties of sediment showed that high content of sediment water content and humic acid would affect the extraction efficiency of sample pretreatment. The method was applied to environmental sediment to quantify pesticide residues in the samples. Based on the instrument and method performance validation results, the developed methods can be applied in environmental pesticide residue analysis, thus providing a scientific method for the detection of sediment samples.

Quantification of dimethoate and chlorpyrifos residues in green leafy vegetables by laser-induced breakdown spectroscopy

The presence of pesticide residues in food represents a significant threat to consumers, mainly due to their toxicity to humans. Evidence has even been found that determines the relationship between many diseases and deaths from ingestion, contact, or mishandling. The need to introduce controls on pesticide residues has become an issue of central concern to society, given the increasing knowledge about the potential dangers associated with the use of pesticides. So the objective of the present study was to evaluate and analyze the feasibility of using the laser-induced breakdown spectroscopy technique as a potential tool for the quantification of dimethoate and chlorpyrifos in green leafy vegetables. For this purpose, reference samples with powdered chard were made using the aforementioned pesticides, with increasing concentrations in a range of 0–80 mg kg−1 and 0–250 mg kg−1, respectively. By applying calibration curves, it was possible to quantify pesticide residues by measuring S (416.26 nm), P (460.21 nm), and Cl (837.59 nm) emission lines, with limits of detection of 1.7 mg kg−1, 0.8 mg kg−1, and 6.9 mg kg−1 respectively. Clear evidence of the applicability of this technique as a potential tool for the study of pesticides in food matrices was established. It was achieved by minimum sample preparation, ensuring a rapid analysis, low application costs, and without toxic waste production. In this way, its use as a preliminary evaluation technique or complementary to the analytical methods traditionally already used is evidenced.

ZIF-8 derived TiO2/ZnO heterostructure decorated with AgNPs as SERS sensor for sensitive identification of trace pesticides

Pesticides are still abused and overused in agricultural production. Food safety monitoring in terms of reliable detection and quantification of pesticide residues is an ever increasing need. Surface-Enhanced Raman Scattering (SERS)-based chemical sensors and adsorption materials crafted for specific pesticide should provide high sensitivity and selectivity. Herein, zeolitic imidazolate framework (ZIF-8) derived TiO2/ZnO three-dimensional (3D) heterostructures were constructed on FTO substrate and were utilized to assemble silver nanoparticles (AgNPs) to create electromagnetic hot spots. The formation of TiO2/ZnO heterostructure greatly improve the SERS performance of the substrate. The calculated enhancement factor (EF) of the TiO2/ZnO/Ag is 39-fold higher than the TiO2/Ag substrates. Furthermore, the substrate shows high signal sensitivity and reproducibility for rapid detection of multiple pesticides. Even with a portable Raman device, the substrate was found to be highly efficient for model molecules of crystal violet (CV) and 4-mercaptobenzoic acid (4-MBA), and the limit of detection (LOD) for both of 10−9 M was demonstrated. Importantly, real life detection of multiple pesticides residues can be achieved with the TiO2/ZnO/Ag sensor, which was demonstrated by the detection of three common pesticides, thiram, acephate and phoxim at trace concentrations.

A plasmonic AgNP decorated heterostructure substrate for synergetic surface-enhanced Raman scattering identification and quantification of pesticide residues in real samples.

Rapid and on-site Raman spectroscopic identification and quantification of pesticide residues have been restricted to the low instrumental sensitivity of a portable Raman instrument, and no ideal platforms have been reported for analyzing pesticides on real sample surfaces. An efficient method to improve the detection sensitivity is to fabricate a highly sensitive surface-enhanced Raman scattering (SERS) substrate. Here, we present a MOF-derived ZnO@TiO2 heterostructure combined with plasmonic AgNPs as a SERS sensor to achieve synergetic EM and CM enhancement, exhibiting high sensitivity, excellent signal reproducibility (RSD < 5.9%) and superior stability for analysis of model molecules. The SERS sensor achieved a low detection concentration of 10-8 M for both CV and R6G molecular solutions on a portable Raman device. As a proof of concept, we modelled a pesticide residue on real samples of dendrobium leaves. Thiram, triazophos and fonofos solutions were selected as analytes for mimicking the function of on-site analysis. The SERS analytical platform showed not only high sensitivity for single- and multi-component identification, but also quantitative detection of pesticide residues on dendrobium leaves. These preliminary investigations indicate that this SERS analytical platform will allow the development and potential applications in rapid and on-site pesticide analysis.

A portable SERS sensing platform for the multiplex identification and quantification of pesticide residues on plant leaves

The synergetic effect of the ZnO@Co3O4 and the plasmonic AgNPs together with the molecular preconcentration enabled it to ultrasensitively and quantitatively detect organophosphorus pesticides on real samples on a portable Raman instrument.