Development and validation of multiresidue analysis method for biomonitoring of pesticides and metabolites in human blood and urine by LC-QToF-MS.

The widespread use of pesticides and their consequential presence in the environment is a growing concern due to the harmful health effects associated with pesticide exposure. For clinical and toxicology laboratories, a method for simultaneously determining these compounds and their metabolic products in body fluids, such as blood and urine, is important. In the present study, a rapid, sensitive and simultaneous LC-QToF-MS method for detecting multiclass pesticides and metabolites in blood and urine samples has been developed and validated. Four sample preparation procedures, protein precipitation and three different variants of QuEChERS-based extraction were evaluated to find a suitable, simple, and effective sample pretreatment technique. The final optimized sample preparation method (acetonitrile; 400 µl, MgSO4; 40 mg and NaCl; 10 mg) was validated for accuracy, precision, matrix effect, recovery, stability, carryover, and dilution integrity. Analyte recoveries ranged from 75.40 to 113.54 % while accuracy was evaluated in the range of 71.41-108.26 % and precision (%RSD) in the range of 0.01 %-16.85 %. The limit of quantification (LOQ) for all compounds was established in the range of 0.82-7.05 ng mL-1. The developed reliable, robust, and sensitive method was successfully applied for the quantification of target pesticides and metabolites in human blood and urine samples. Evaluated samples resulted in detection of eleven analytes (seven pesticides and four metabolites).

[Effects of Continuous Cropping on the Physiochemical Properties, Pesticide Residues, and Microbial Community in the Root Zone Soil of Lycium barbarum].

Continuous cropping is a common obstacle limiting the high quality and yield of Lycium barbarum （wolfberry）. To clarify the response of soil characteristics of the wolfberry root zone to continuous cropping years, we systematically determined the physicochemical properties and pesticide residues of soils in the wolfberry root zone with different continuous cropping years. In addition, soil bacterial and fungal communities were characterized using high-throughput sequencing technology. The results were as follows： The content of total salt and imidacloprid in the root zone of wolfberry increased with increasing years of continuous cropping. Compared to that with 2 and 9 years, the total salt content in the root zone of wolfberry with 15 years of continuous cropping increased by 51.97% and 54.33%, respectively, and the imidacloprid content increased by 39.58% and 36.61%, respectively. Alkaline nitrogen and available potassium showed an increasing and then decreasing trend. Compared to that with 2 and 15 years, alkaline nitrogen and available potassium in the root-soil of wolfberry with 9 years of continuous cropping increased by 16.94%-28.09% and 18.31%-18.34%, respectively. The diversity and abundance of bacterial communities and the abundance of fungal communities were higher in the root-soil of wolfberry with 9 years of continuous cropping compared to that with 15 years of continuous cropping. In addition, the increase in continuous cropping years also increased the accumulation of harmful plant pathogens such as Pseudomonas, Arthrobacter, Actinomucor, and Trichoderma in the root zone of L. barbarum. Soil total salinity, organic matter, alkaline hydrolyzable nitrogen, and available potassium were the main factors influencing the distribution of bacterial communities. Soil alkaline hydrolyzable nitrogen, available potassium, and ammonium nitrogen were the main factors influencing the distribution of fungal communities. In addition, the soil bacteria in the root zone of L. barbarum were dominated by metabolic functions； in particular, amino acid metabolism, energy metabolism, and nucleotide metabolism were most abundant in the root soil of wolfberry with 9 years of continuous cropping, whereas the highest abundance of functional genes related to membrane translocation was found in the root-soil of wolfberry with 15 years of continuous cropping. The soil fungi were all dominated by saprophytic trophic types, followed by pathogenic cross-nutrients in the root zone of L. barbarum. In conclusion, long-term continuous cropping induced changes in the soil microenvironment in the root zone of L. barbarum, increased soil residues of harmful pesticides and the enrichment of plant pathogens, and reduced the diversity of soil bacterial and fungal communities. Therefore, it is necessary to control the rate of application of soil nutrients and pesticides in the management of L. barbarum and to carry out deep ploughing and deep tilling in good time, and the turnover of old plants in the cultivation of L. barbarum.

Monitoring pesticide residues in pepper (Capsicum annuum L.) from Al-Qassim region, Saudi Arabia: Occurrence, quality, and risk evaluations.

The Al-Qassim region, a prominent agricultural hub in Saudi Arabia, significantly contributes to the national production of vegetables and fruits. This study validated the standard EN-QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) method in conjunction with liquid chromatography-tandem mass spectrometry (LC-MS/MS) to determine 90 multiple pesticide residues in three categories of peppers: green bell, green hot and red chilli peppers. Validation criteria, including linearity range, accuracy, precision, limit of detection (LOD), and limit of quantification (LOQ), were within the acceptance range of the SANTE/11312/2021 guideline. The validated method was then used to analyse 536 pepper samples collected in 2023 from the Al-Qassim region of Saudi Arabia. The analysis of 536 pepper samples revealed that 394 samples (73.51 %) contained pesticide residues, with 126 (23.51 %) exceeding the established maximum residue limits (MRLs). The most frequently identified pesticide was imidacloprid (171 samples, 31.9 %) and acetamiprid (94 samples, 17.54 %), followed by bifenazate and difenoconazole, which were each detected in 66 samples (12.31 %). Among the remaining 32 pesticides, 24 were detected in 1%-10 % of the samples, whereas 8 were detected in <1 %. The 36 pesticides detected were classified into 14 insecticides (38.9 %), 14 fungicides (38.9 %) and 8 acaricides (22.2 %). Notably, the overall detection rate of the pesticides was relatively higher in red chilli peppers (232 %) compared with bell peppers (165 %), followed by green hot peppers (132 %). Red chilli peppers also showed the highest residue concentrations of various pesticides. Neonicotinoids and triazoles exhibited the highest detection rates in this study. The residue quality index (IqR) of the samples analysed fell into the categories excellent (26.49 %), good (31.72 %), and adequate (14.06 %), with 28.73 % of the samples deemed inadequate. Long-term dietary exposure was examined for adults and children. This study highlights the crucial role of continual observation in defending public health and securing the trade standardisation and safety.

Novel electrochemiluminescence platform utilizing AuNPs@Uio-66-NH2 bridged luminescent substrates and aptamers for the detection of pesticide residues in Chinese herbal medicines.

A large number of Chinese herbal medicines (CHMs) are included in daily recipes, but their pesticide residues have aroused more and more concerns. In this paper, an electrochemiluminescence aptasensor was constructed for the trace detection of acetamiprid (ACE) in Angelica sinensis and Lycium barbarum. Possessing a large specific surface area, UiO-66 was modified with amino groups to improve biocompatibility, and the addition of AuNPs allowed UiO-66-NH2 to catalyze the formation of excited states of luminescent molecules (TPrA⁎; Ru(bpy)32+⁎), and AuNPs@UiO-66-NH2 was used to bridge the aptamer (Au-S) and luminescent substrate (peptide bond). The conventional luminescent reagent Ru(bpy)32+ was doped with multi-walled carbon nanotubes (MWCNTs) to obtain a more powerful and stable light signal. After optimizing the experimental parameters, the aptasensor could give results in 10 min with a detection range from 1×10-2-1×104 nM and a lower limit of detection (LOD) of 0.8 pM. The LOD of the study was at least one order of magnitude lower than that of the fluorescence detection method. Furthermore, the accuracy of the aptasensor was validated for spiked recovery experiments.

Pesticides in widely consumed vegetables in Bangladesh and its health risk.

This study analysed pesticide residues in cauliflower (Brassica oleracea botrytis) and bitter gourd (Momordica charantia), two widely consumed vegetables in Bangladesh, and assessed the associated human health risks. Vegetables were analysed using a modified QuEChERS extraction, followed by gas chromatography with flame thermionic and electron capture detectors. Results showed that in 36.7% of the samples pesticide residues were detected, 90.9% of which exceeding the MRLs of the European Commission, so highlighting serious food safety concerns. Multiple residues were detected in some samples, with chlorpyrifos being the most common present, followed by diazinon, dimethoate and quinalphos. Human health risks, calculated by estimated daily intake and hazard index, indicated potential non-carcinogenic risks from the present pesticides. This study may assist policymakers and authorities in developing strategies for safe vegetable production and quality monitoring to ensure food safety.

3D hot spot construction on the hydrophobic interface with SERS tags for quantitative detection of pesticide residues on food surface.

The overuse of pesticides results in excessive pesticide residues, posing a potential threat to human health. Herein, this work proposes a SERS substrate for the quantitative analysis of pesticide residues on food surfaces. Au cores are assembled on PS microspheres, followed by the modification of Raman internal standards (1,4-BDT) on the gold core surface and the growth of the Au shell. After incubating the analytes with PS@Au@1,4-BDT@Au particles, the mixture is dropped on the hydrophobic gold film for drying before detection. The SERS substrates exhibited high sensitivity and stability, with a detection limit of 10-12 M and an RSD of less than 7 %. Combined with a portable Raman spectrometer, the SERS detection of pesticide residues on three kinds of food surfaces is carried out, with a sensitivity of 10-11 M, meeting the US MRLs regulations. Therefore, this strategy may possess significant potential for future food safety.

[Review and prospects of pesticide use and residues in cultivation of medicinal and food homologous substances].

As people's living standards and awareness of health care are increasing in recent years, the demand for the medicinal and food homologous substances is rising. Promoting the healthy development of this industry to meet people's growing demand and popularizing the TCM concept of preventive treatment of diseases are essential for building a healthy China. The abuse of pesticides by some growers in the one-sided pursuit of economic benefits causes serious pesticide residue, which affects the safety and effectiveness of the medicinal and food homologous substances. Since pesticide residues has received increasing attention, the reasonable control of pesticide residues becomes an important part of the research on these herbs, which, however, is rarely studied. This paper reviewed the publications involving pesticide residues in the cultivation of medicinal and food homologous substances that were published in the last two decades, and put forward the problems faced by the cultivation. According to the current situation of this industry, this paper proposed the management suggestions for the control of pesticide residues in the cultivation. This review will provide the government with data and references for formulating relevant policies and standards to promote the high-quality development of the industry of medicinal and food homologous substances and guarantee the development of TCM and the building of a healthy China.

Honey bees for pesticide monitoring in the landscape: Which bee matrices should be used?

Among bee species, the western honey bee (Apis mellifera) is preferred in monitoring studies performed in the agricultural landscape, while bee matrices, pollen, and honey are mostly a subject of these studies due to their unique composition. A justified question about the relevance of other bee matrices, like larvae, foragers, beebread, and/or wax, has been raised. The ability of different bee matrices (wax, pollen grains, bee bread, foragers, larvae, nectar, and honey) to absorb pesticide residues is subjected in this study. All samples were collected during a crop flowering season (oilseed rape) on intensively managed agricultural land in Slovakia and Germany. The observed high variability in residue levels, profile, and number of detections among studied matrices from Germany, west, and east Slovakia gave us an assumption of the use of different agricultural practices between these two countries. Fungicides clearly dominated across all samples in all sampling regions. The increased pesticide profile positively correlated with the oilseed rape pollen grains in pollen pellets and/or bee bread. Bee wax, pollen, and bee bread showed a high number of detected active substances and total residue concentrations among matrices, indicating their high ability to absorb pesticide residues in the surrounding hive environment.

Advances on multiclass pesticide residue determination in citrus fruits and citrus-derived products - A critical review.

The application of agrochemicals in citrus fruits is widely used to improve the quality of crops, increase production yields, and prolong post-harvest life. However, these substances are potentially toxic for humans and the ecosystem due to their widespread use, high stability, and bioaccumulation. Conventional techniques for determining pesticide residues in citrus fruits are chromatographic methods coupled with different detectors. However, in recent years, the need for analytical strategies that are less polluting for the environment has encouraged the appearance of new alternatives, such as sensors and biosensors, which allow selective and sensitive detection of pesticide residues in real time. A comprehensive overview of the analytical platforms used to determine pesticide residues in citrus fruits and citrus-derived products is presented herein. The review focuses on the evolution of these methods since 2015, their limitations, and possible future perspectives for improving pesticide residue determination and reducing environmental contamination.

Sensitive extraction of seven pesticide residues from environmental water with magnetic graphene oxide-based covalent organic framework.

The use of pesticides has increased with the development of agriculture. However, due to the trace content and the matrix's inherent complexity in environmental water, development of rapid and sensitive detection method present significant challenges in the analysis of pesticide residues. The study synthesized magnetic graphene oxide (MGO) by combining superparamagnetic nanoparticles with the easy modification of graphene oxide (GO). Covalent organic frameworks (COFs) were then modified to have a large specific surface area. Finally, magnetic graphene oxide-based covalent organic frameworks, namely MGO-COFs, were obtained with a spherical structure and used as magnetic solid-phase extraction materials, which was successfully used to determine the seven pesticide residues in environmental samples in conjunction with high performance liquid chromatography. The method has a wide linear range for the tested pesticides, with satisfactory correlation coefficients (R ≥ 0.099) and low detection limits (0.3-1.21 µg L-1). The correlation coefficients for all seven pesticides were high (R2 ≥ 0.9996). The spiked recoveries, exhibiting a range of 91.3 to 109 %, demonstrated that the developed MGO-COF-MSPE-HPLC-UV method is simple, efficient, and suitable for the analysis and detection of seven pesticide residues in environmental water.

Pesticide residues in European sediments: A significant concern for the aquatic systems?

The presence of pesticide residues in waterbed sediments poses a significant concern for aquatic ecosystems' health. This study examined pesticide contamination in sediments of 38 water bodies, embedded in agricultural-dominated regions, across eight European countries. Three indicators were targeted: occurrence, type, and concentrations of multiple pesticide residues in sediments. 196 pesticide residues (including degradation products) were tested in the sediment samples. The analytical results showed that only one sample was 'pesticide-free', three samples contained a single pesticide residue, and the remaining 34 samples contained mixtures of residues. Overall, 99 different residues were found in the sediments, with a maximum of 48 in a single sample. Twenty-seven out of the 99 detected residues were not approved for agricultural use at the time of sampling. The numbers of detected residues and pesticide levels varied among countries. AMPA, glyphosate and DDTs were the most common residues in sediment samples with frequencies of 76, 61, and 52%, respectively. The sediments from the Czech Republic had the highest pesticide concentrations, with total pesticide concentrations ranging between 600 and 1200 µg kg-1. The lowest total pesticide concentrations were found in Slovenia, Switzerland, Croatia, and Denmark, ranging between 80 and 120 µg kg-1. Sediments presented a mix of non-persistent and persistent compounds. Twelve of the detected pesticides are very persistent/stable in sediments, raising concerns about the long-term impacts of pesticides. Our study on the distribution of pesticide residues in European sediments provides valuable insights into the extent of pesticide contamination and possible risks of pesticides to water bodies' health. It also underlines the need for monitoring, research, and policy efforts to mitigate the impacts of pesticides, and to evaluate potential risks of re-use of dredged sediments.

A potential toxicological risk assessment of heavy metals and pesticides in irrigated rice cultivars near industrial areas of Dhaka, Bangladesh.

Rice intake represents a significant pathway through which humans accumulate heavy metals. This study presents a comprehensive analysis of heavy metal and pesticide contamination in rice cultivars irrigated with industrial wastewater near Dhaka, Bangladesh, a region heavily influenced by industrial activities. This study employed a unique methodology that not only quantified the concentrations of heavy metals and pesticide residues in rice grains but also extended to evaluating the physicochemical properties of rice stems, husks, soil, and irrigation water. The findings revealed alarmingly high levels of heavy metals such as lead, cadmium, chromium, nickel, and mercury in the soil and irrigation water, with concentrations in some cases exceeding the World Health Organization safety thresholds by 2 to 15 times. Notably, the rice grains also exhibited significant contamination, including substantial amounts of diazinon and fenitrothion pesticides, exceeding the established safety limits. The study employed hazard quotients (HQs) and cancer risk (CR) assessments to evaluate the potential health risks associated with the consumption of contaminated rice. The results indicated HQ values were greater than 1 for rice grains across the sampled fields, suggesting a considerable non-carcinogenic health risk, particularly from lead exposure, which was found at levels twice the standard limit in all the sampling fields. Moreover, the CR values for As, Pb, Cd, Co, and Mn highlighted a significant carcinogenic risk in several instances.

Cumulative dietary risk assessment for French consumers exposed to succinate dehydrogenase inhibitor pesticides.

Consumers are exposed to succinate dehydrogenase inhibitor (SDHI) pesticides through their diet. A cumulative dietary risk assessment for the French population has been performed with French monitoring data (2017-2021) and consumption data from INCA3. The calculation followed a two-tiered approach, using deterministic then probabilistic methods. It was carried out, using European health based guidance values (HBGV) derived for each active substance to characterise their toxicity. In Tier I, the calculated hazard index of 0.12 was below the threshold of 1 and in Tier II, the total margin of exposure at percentile 99.9 remains above the trigger value of 100 (1798 [1631-2311]). In Tier II, the three main risk drivers identified at the upper tail of the distribution were strawberries-fluopyram (19.1%), peaches-fluopyram (14.1%) and table grapes-boscalid (10.5%). Finally, the impact of the major sources of uncertainties was qualitatively evaluated. All together, they were considered of low impact on the outcomes. This work demonstrates the absence of unacceptable chronic risk related to the cumulative exposure of SDHI for French consumers during the 2017-2021 period.

Introducing high-performance star-shaped bimetallic nanotags into SERS aptasensor: An ultrasensitive and interference-free method for chlorpyrifos detection.

Implementation of cost-effective, reliable, and efficient technologies for the sensitive, rapid, and accurate detection of pesticide residues in agriproducts presents a promising solution to the escalating food safety concerns. Herein, a high-performance surface-enhanced Raman scattering (SERS) aptasensor based on nanotag (AuNS@4-MBN@Ag-aptamer) was introduced for ultrasensitive, reliable, and interference-free detection of chlorpyrifos (CPF). This aptasensor featured star-shaped bimetallic nanotag as the principal Raman signal enhancement material and 4-mercaptobenzonitrile (4-MBN) as "biological-silent"-window reporter (at 2228 cm-1). Moreover, cDNA-linked Fe3O4@AuNPs (FA-cDNA) served as magnetic substrates to simplify the separation process of FA-cDNA-combined nanotags. In the aptasensor, the formation of FA-cDNA-aptamer-AuNS@4-MBN@Ag hybrids was hindered by CPF, and its Raman intensity decreased with increasing CPF concentration. Under optimal SERS conditions, the aptasensor exhibited a broad linear detection range from 2.5 × 102 to 5.0 × 104 pg⋅mL-1, with an impressively low limit of detection of 220.35 pg⋅mL-1 (signal-to-noise ratio = 3). The selectivity and reproducibility assessments highlighted its exceptional sensitivity and interference-free capabilities. Furthermore, practical applications on wheat and apples demonstrated satisfactory spiked recovery rates, ranging from 89.61% to 107.33% (relative standard deviation ≤ 14.55%). Consequently, the high-performance "biological-silent"-window nanotag-based aptasensor is a promising tool for monitoring trace CPF in complex matrices.

Unveiling the Contamination Patterns of Neonicotinoid Insecticides: Detection, Distribution, and Risk Assessment in Panax notoginseng across Plant Parts.

This study analyzed neonicotinoid insecticides (NEOs) and metabolite (m-NEOs) residues in 136 Panax notoginseng samples via ultra-performance liquid chromatography-tandem mass spectrometry. Imidacloprid was the most detected NEO (88.24% of samples), ranging from 1.50 to 2850 µg/kg. To the best of our knowledge, some novel NEOs were detected in P. notoginseng for the first time. NEO clustering patterns varied among plant parts, with higher contamination in leaves and flowers. Fourteen NEO/m-NEOs, including cycloxaprid and acetamiprid, showed site-specific behavior, indicating the possibility of using multiple NEOs simultaneously during planting, resulting in formation of distinct metabolites in different plant parts. Transfer rates in decoction and infusion ranged from 10.06 to 32.33%, reducing residues postprocessing. Dietary risk assessment showed low hazard quotients (HQa: 7.05 × 10-7 to 2.09 × 10-2; HQc: 3.74 × 10-7 to 2.38 × 10-3), but risk-ranking scores indicated potential hazards with imidacloprid and acetamiprid in flowers and leaves. The findings are expected to promote safety assessment and distribution research of NEOs in plants.

Rhamnolipids-based bio-supramolecular solvents as green and sustainable media for extraction of pyrethroid insecticides in water and food matrices.

A novel bio-supramolecular solvent (bio-SUPRAS) based on rhamnolipids (RLs) was designed for efficient extraction of pyrethroid insecticides in water and food matrices. Benefiting from RLs as amphiphiles equipped with the attractive properties of bio-degradable, low toxicity and high stability, bio-SUPRAS was spontaneously generated through salt induced coagulation. The bio-SUPRAS was characterized by cryo-scanning electron microscope and main factors influencing the extraction performance were investigated in detail. Under the optimized conditions, the method was found to have desirable limits of detection (5∼10 µg l-1), good precision (RSDs<16.9 %) and satisfactory recovery (75.2 %∼94.3 %). More importantly, the extraction mechanism was studied by density functional theory systematically. Following greenness assessment, the technique was successfully used for enrichment of pyrethroid pesticides in real samples before HPLC-UV analysis. Thus, the method showed the outstanding merits of eco-efficient, green, time-saving, and had favorable application prospect to remove trace analytes from intricate sample matrices.

Dissipation kinetics and the evaluation of dietary risks associated with deltamethrin, ethion, fenazaquin, and fenpropathrin on bell pepper (Solanum annuum L.).

Bell peppers, a globally significant crop, face infestations from various pests. In a study, bell peppers were treated with deltamethrin, ethion, fenazaquin, and fenpropathrin at recommended and double the doses, repeated twice with a 10-day interval. The QuEChERS method underwent validation for linearity, matrix match, accuracy, and precision in bell pepper matrices for residue analysis. The limit of detection for the tested pesticides on bell peppers was 0.01 mg/L, with a quantification limit of 0.05 mg/L. Recovery studies showed a range of 94.80% to 102.80%. Initial deposits of deltamethrin, ethion, fenazaquin, and fenpropathrin on bell peppers at recommended doses were 0.371, 1.237, 0.617, and 0.640 mg/L, respectively, and at double doses were 0.712, 1.945, 1.221, and 1.189 mg/L, respectively. Safe waiting periods of 10, 11, 10, and 8 days were suggested for deltamethrin, ethion, fenazaquin, and fenpropathrin, respectively. The corresponding half-lives for the pesticides were 1.96, 1.79, 2.06, and 1.69 days, all following first-order dissipation kinetics. Dietary risk assessment indicated Hazard Quotients (HQ) below 1 and Theoretical Maximum Daily Intake (TMDI) below Acceptable Daily Intake (ADI) and Maximum Permissible Intake (MPI) levels. Therefore, at their recommended doses, the pesticides were deemed safe for bell pepper cultivation.

Identifying pesticides of high concern for ecosystem, plant, animal, and human health: A comprehensive field study across Europe and Argentina.

The widespread and excessive use of pesticides in modern agricultural practices has caused pesticide contamination of the environment, animals, and humans, with confirmed serious health consequences. This study aimed to identify the 20 most critical substances based on an analysis of detection frequency (DF) and median concentrations (MC) across environmental and biological matrices. A sampling campaign was conducted across 10 case study sites in Europe and 1 in Argentina, each encompassing conventional and organic farming systems. We analysed 209 active substances in a total of 4609 samples. All substances ranked among the 20 most critical were detected in silicon wristbands worn by humans and animals and indoor dust from both farming systems. Five of them were detected in all environmental matrices. Overall, higher values of DF and MC, including in the blood plasma of animals and humans, were recorded in samples of conventional compared to organic farms. The differences between farming systems were greater in the environmental samples and less in animal and human samples. Ten substances were detected in animal blood plasma from conventional farms and eight in animal blood plasma from organic farms. Two of those, detected in both farming systems, are classified as hazardous for mammals (acute). Five substances detected in animal blood plasma from organic farms and seven detected in animal blood plasma from conventional farms are classified as hazardous for mammals (dietary). Three substances detected in human blood plasma are classified as carcinogens. Seven of the substances detected in human blood plasma are classified as endocrine disruptors. Six substances, of which five were detected in human blood plasma, are hazardous for reproduction/development. Efforts are needed to elucidate the unknown effects of mixtures, and it is crucial that such research also considers biocides and banned substances, which constitute a baseline of contamination that adds to the effect of substances used in agriculture.

Determination of multi-residue pesticides in dairy products using single-step emulsification/demulsification clean-up strategy combined with low-pressure gas chromatography-tandem mass spectrometry.

In this study, a simple, sensitive, and rapid method was developed for the simultaneous determination of 99 kinds of pesticides in fatty milk samples. This novel emulsification-demulsification clean-up approach, coupled with an automatic demulsification-dehydration cartridge, allowed rapid single-step clean-up operation and high throughput. It also achieved effective and selective removal of lipids. The analysis was performed using low-pressure gas chromatography-tandem mass spectrometry (LPGC-MS/MS). Based on the optimal conditions, the targeted pesticides showed good linearity in the range of 5-250 µg/kg, with recoveries of 70-120% at spiking levels of 5, 10, and 20 µg/kg in cow milk, goat milk, and almond milk, respectively. The limit of quantification for most pesticides was 5 µg/kg, and the RSDs were lower than 20%. Analysis of real dairy products obtained from local markets revealed a potential risk in plant-derived almond milk, but no significant risks were found for cow and goat milk.

Occurrence and seasonal variation of organochlorine pesticides in selected vegetable farmlands in Lagos State, Nigeria.

Pest infestation in crop production have increased farmers' interest in pesticides use with short and long term consequences. This study investigated the occurrence and seasonal variations of organochlorine pesticide residues in vegetable farms in selected areas of Lagos State. Non carcinogenic and carcinogenic risk assessment was also evaluated. Soil samples were collected during the wet and dry seasons at soil depth of 0-30 cm. Gas chromatography coupled with an Agilent mass spectrometer was used to analyse organochlorine residues (alpha-lindane,lindane, delta.-lindane, aldrin, heptachlor epoxide, alpha.-endosulfan, p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE), endrin, endosulfan, m,p'-dichlorodiphenyldichloroethane (m,p'-DDD), endosulfan sulfate, o,p'-dichlorodiphenyltrichloroethane (o,p'-DDT) and endrin ketone) in soil. Heptachlor epoxide showed maximum concentration of 43.03 mg/kg in Station 19 in Western zone during the dry season while m,p'-DDD and endosulfan had minimum value of 0.004 mg/kg in Station 2 and Station 5 respectively during the wet season in the Far eastern zone. The concentrations of organochlorine residues were intermediate in the Eastern zone in both seasons. There was significant (p < 0.05) increase in dry season concentrations when compared to wet season. The risk assessment indicated Hazard Quotient (HQ) > 1 for non-cancer risk and cancer risk > 10-6. Thus a need for stringent monitoring programs for pesticides.