Pyrethroid Pesticide Residues Research Articles

Organophosphate, Carbamate and Synthetic Pyrethroid Pesticide Residues in Muscle Tissues of Fish from Loktak Lake, a Ramsar Site in Manipur, India

The muscle tissues of Channa punctatus and Anabas testudineus collected from the Loktak Lake (a Ramsar site) and its three major feeder rivers in Manipur, Northeastern India, were analyzed using high-performance liquid chromatography for the presence of residues of three organophosphorus (malathion, dichlorvos and monocrotophos), one carbamate (carbofuran), and two synthetic pyrethroid (deltamethrin and cypermethrin) pesticides. Residues of all the pesticides except monocrotophos were detected in the fish tissues. Among the five pesticides detected, concentrations of dichlorvos exceeded the maximum residue limit (MRL) prescribed by the Codex Alimentarius for animal tissues such as mammalian offal, eggs and poultry meat. The rest of the compounds were within the MRL for eggs and animal tissues. None of the pesticide residues was detected in the two fish species collected from the control or reference site. The present study indicates that pesticide contamination is emerging as a threat to the water quality and aquatic biodiversity of Loktak Lake, which is a “wetland of international importance” (Ramsar Site) located in a global biodiversity hotspot. The findings of this study also calls for more detailed investigations on the presence of pesticide residues in water, sediments, aquatic macrophytes, planktonic and benthic organisms, and different fish species of this wetland ecosystem.

Ultra-performance liquid chromatography-tandem mass spectrometry for quantification of pyrethroid pesticide residues in freshwater fish and shrimp

A sophisticated Ultra-Performance Liquid Chromatography-Tandem Mass Spectrometry (UPLC-MS/MS) approach was devised for the concurrent quantification of pyrethroid pesticide residues in freshwater fish and shrimp. This analytical method involved ultrasonic extraction using acetonitrile, succeeded by sample purification employing Primary Secondary Amine (PSA) and Zirconium Dioxide Silica (Z-Sep+) following low-temperature centrifugation. Chromatographic separation was achieved with an ACQUITY UPLC BEH C18 column utilizing a mobile phase of a 2 mmol/L ammonium formate aqueous solution and methanol, with detection conducted through ESI + ionization in Multiple Reaction Monitoring (MRM) mode. The assay demonstrated exceptional linearity for seven pyrethroids across a concentration range of 0.5–10 μg/L, evidenced by correlation coefficients surpassing 0.999. Detection limits were established between 0.08 and 0.52 μg/kg, and the lower limits of quantification ranged from 0.28 to 1.72 μg/kg. Furthermore, recovery rates for blank samples were outstanding, ranging from 91.40% to 108.83% at concentrations of 1.0, 4.0, and 20.0 μg/kg, with Relative Standard Deviations (RSDs) between 0.94% and 8.13%. This methodology proved to be rapid, convenient, sensitive, and robust, offering stable recovery rates. Notably, it facilitated the detection of seven pyrethroid pesticide residues in freshwater fish and shrimp within an expedited timeframe of 15 min. This pioneering technique constitutes a significant advancement in the development of new methods for ensuring food safety.

Simultaneous Determination of Seven Pyrethroid Pesticide Residues in Aquatic Products by Gas Chromatography

Aquatic products are good sources of essential nutrients, but the presence of pyrethroids (PYRs) as contaminants may pose risks to consumer health as the intricate matrices of PYRs usually obstruct chemical hazard detection. In this study, a gas chromatographic method was established and validated for simultaneously detecting residues of seven PYRs (cyhalothrin, permethrin, cyfluthrin, cypermethrin, tau-fluvalinate, fenvalerate, deltamethrin) in aquatic products. The aim of this method was to assess better the potential risks of pesticide residues in aquatic products. The PYRs in aquatic products were extracted with acetonitrile, purified with n-hexane saturated with acetonitrile, and cleaned up on a Cleanert® Alumina N column. Statistical analysis and orthogonal array experimental design were used to optimize the key parameters. To validate the proposed method, commonly consumed aquatic products (such as carp, crucian carp, whiteleg shrimp, river crab, sea cucumber, and scallop) were obtained from local supermarkets in Shanghai. Satisfied linearity of the calibration curves was achieved in a matrix-matched standard solution, with a correlation coefficient (R2) larger than 0.995. The average recoveries at five fortification levels varied from 77.0% to 117.2%, with relative standard deviations (RSDs) below 11.1%. Concerning electron capture detection, the limits of detection (LOD) and limits of quantification (LOQ) were 2.0–5.0 µg/kg and 5.0–10.0 µg/kg, respectively. These results demonstrate the high stability and sensitivity of this method for simultaneously detecting PYRs in aquatic products, having great practicability and which can be popularized easily.

Microbial Fermentation as an Efficient Method for Eliminating Pyrethroid Pesticide Residues in Food: A Case Study on Cyfluthrin and Aneurinibacillus aneurinilyticus D-21.

The microbial fermentation of food has emerged as an efficient means to eliminate pesticide residues in agricultural products; however, the specific degradation characteristics and mechanisms remain unclear. In this study, a Gram-positive bacterium, Aneurinibacillus aneurinilyticus D-21, isolated from fermented Pixian Douban samples exhibited the capability to degrade 45 mg/L of cyfluthrin with an efficiency of 90.37%. Product analysis unveiled a novel cyfluthrin degradation pathway, involving the removal of the cyanide group and ammoniation of the ester bond into an amide. Whole genome analysis discovered the enzymes linked to cyfluthrin degradation, including nitrilase, esterase, carbon-nitrogen ligases, and enzymes associated with aromatic degradation. Additionally, metabolome analysis identified 140 benzenoids distributed across various aromatic metabolic pathways, further substantiating D-21's catabolic capability toward aromatics. This study underscores the exceptional pyrethroid degradation prowess of A. aneurinilyticus D-21, positioning it as a promising candidate for the biotreatment of pesticide residues in food systems.

Polyaniline-coated kapok fibers for convenient in-syringe solid-phase microextraction and determination of organochlorine and pyrethroid pesticide residues in aqueous samples

Pesticides used in agriculture have low polarity and a tendency to accumulate in fatty tissues, posing potential risks to human health. Effective pre-treatment is crucial due to complex sample matrices and low concentrations of pesticide residues typically encountered in instrument analysis. In this study, polyaniline-coated kapok fiber (PANI-KF) was synthesized successfully using in-situ oxidative polymerization for use as sorbents in in-syringe SPME of pyrethroid pesticides (PYRs) and organochlorine pesticides (OCPs) from aqueous samples. Coating the natural KF with PANI maintained the hollow microtubular structure and fiber morphology while significantly enhancing the extraction efficiency. The extraction process was easily conducted by simply pulling and pushing the syringe plunger. The entire extraction process, utilizing 3 mg of PANI-KF, could be completed in approximately 3 min. Density functional theory results indicated that the adsorption mechanism of PANI-KF towards OCPs and PYRs mainly involved van der Waals interactions, π-π interactions, and weak hydrogen bonding interactions. With the coupling of gas chromatography-mass spectrometry, a quantification method was established that exhibited good linearities (R2 > 0.990), and relative recoveries (87.2–108.5 %). The limits of detection ranged from 0.4 to 2.0 ng mL−1 and the matrix effects were negligible (−12.3–16.4 %). The validated in-syringe SPME-GC-MS method was successfully applied to determine pesticide residues in fruit juices, oral liquids and herbal extract granules with satisfactory accuracy and precision. PANI-KF exhibits remarkable promise as a sorbent for the extraction and enrichment of pesticide residues in aqueous samples, thereby contributing to the advancement of pesticide residue determination methodologies.

Plasma-Excited Nebulizer Gas-Assisted Electrospray Ionization: Enhancing the Sensitivity of Pesticide in Mass Spectrometry.

Liquid chromatography-mass spectrometry (LC-MS) is widely used in the detection of pesticide residues. However, the detection sensitivity of low-polarity pesticides by commonly used electrospray ionization may be severely suppressed, which greatly affects the limit of detection and repeatability. Herein, a plasma-excited nebulizer gas-assisted electrospray ionization (PENG-ESI) device has been developed. By introducing the discharge plasma formed by Tesla coil into the electrospray nebulizer gas channel, the sensitivity of low-polarity pesticides was significantly increased while maintaining sensitivity to polar pesticides. Under the optimized conditions, the limit of detection for S-bioallethrin was achieved at the level of 100 pg/g with good linearity (R2 > 0.99) and precision (RSD ≤ 4.61%). The matrix effect of a series of spiked matrix samples is less than 13.1%. Finally, different pyrethroid pesticide residues were successfully analyzed without separation, highlighting that the technology has potential application prospects in food quality control, environmental monitoring, and other fields.

Machine learning-assisted fluorescence sensor array for qualitative and quantitative analysis of pyrethroid pesticides

The simultaneous detection of multiple residues of pyrethroid pesticides (PPs) on vegetables and fruits is still challenging using traditional nanosensing methods due to the high structural similarity of PPs. In this work, sensor arrays composed of three nanocomposite complexes (rhodamine B-CD@Au, rhodamine 6G-CD@Au, and coumarin 6-CD@Au) were constructed to discriminate between structurally similar PPs. Four PPs, deltamethrin, fenvalerate, cyfluthrin, and fenpropathrin, were successfully discriminated. The ability of these sensor units was derived from the different affinity between receptor/analyte and receptor/dye, as well as the non-linear relationship between fluorescence signal and analyte concentration. Upon multivariate pattern recognition analysis, the array performed high-throughput identification of four PPs in unknown samples with 100% classification accuracy. In addition, good accuracy of predicting concentration using the “stepwise prediction” strategy combined with the machine learning method was achieved.

Quantitative determination of organophosphorus, pyrethroid, and dithiolane pesticide residues in brown rice using supercritical fluid extraction and liquid chromatography-tandem mass spectrometry.

Supercritical fluid extraction (SFE) is a fast, versatile, and solvent-efficient automatic extraction method. Despite its advantages, the results of our proficiency tests imply that the applicability assessments of SFE for pesticide residues were insufficient. In this study, as analytical method using SFE was optimized and validated by testing the incurred and fortified brown rice samples with organophosphorus, pyrethroid, and dithiolane pesticides. Validation study using the incurred sample with etofenprox, fenitrothion, and isoprothiolane was performed by comparing the analytical results obtained using the SFE and solid-liquid extraction with homogenization (SLE), which is a well-validated official multi-residue extraction method. The tests on the fortified samples were also performed for seven pesticide residues, chlorpyrifos, diazinon, O-ethyl O-4-nitrophenyl phenylphosphonothioate (EPN), etofenprox, fenitrothion, isoxathion, and isoprothiolane, at three fortification levels, 0.001, 0.01, and 0.1 mg/kg. In the test on the incurred samples, optimized SFE-to-SLE analytical values (CSFE/CSLE) were in 99.2-100.1%, with RSD lower than 3%. In contrast, the analytical-to-spiked concentrations in the tests on the fortified samples were in 96.4-105.0%, with RSD lower than 8.8%. These results indicate that the proposed SFE method, which is well validated with the incurred brown rice sample, is useful for determining organophosphorus, pyrethroid, and dithiolane pesticide residues in brown rice. The proposed SFE method satisfies EU and Japanese maximum residue limits. The consumption of solvent can be reduced to one-fourth of that of SLE using the proposed SFE method.

Multiscale Deepspectra Network: Detection of Pyrethroid Pesticide Residues on the Hami Melon.

The problem of pyrethroid residues has become a topical issue, posing a potential food safety concern. Pyrethroid pesticides are widely used to prevent and combat pests in Hami melon cultivation. Due to its high sensitivity and accuracy, gas chromatography (GC) is used most frequently for detecting pyrethroid pesticide residues. However, GC has a high cost and complex operation. This study proposed a deep-learning approach based on the one-dimensional convolutional neural network (1D-CNN), named Deepspectra network, to detect pesticide residues on the Hami melon based on visible/near-infrared (380-1140 nm) spectroscopy. Three combinations of convolution kernels were compared in the single-scale Deepspectra network. The convolution group of "5 × 1" and "3 × 1" kernels obtained a better overall performance. The multiscale Deepspectra network was compared to three single-scale Deepspectra networks on the preprocessing spectral data and obtained better results. The coefficient of determination (R2) for lambda-cyhalothrin and beta-cypermethrin was 0.758 and 0.835, respectively. The residual predictive deviation (RPD) for lambda-cyhalothrin and beta-cypermethrin was 2.033 and 2.460, respectively. The Deepspectra networks were compared with two conventional regression models: partial least square regression (PLSR) and support vector regression (SVR). The results showed that the multiscale Deepspectra network outperformed the other models. It was found that the multiscale Deepspectra network could be a novel approach for the quantitative estimation of pyrethroid pesticide residues on the Hami melon. These findings can also provide an effective strategy for spectral analysis.

Fe3O4@ZIF-8@SiO2 Core–Shell Nanoparticles for the Removal of Pyrethroid Insecticides from Water

Residues of pyrethroid pesticides in aquatic environments seriously threaten aquatic organisms and the human health. Herein, a novel highly dispersed and recyclable composite ZIF-8 and SiO2 double-layer-modified Fe3O4 nanoparticle, named Fe3O4@ZIF-8@SiO2 nanoparticle, was synthesized via a layer-by-layer assembly method to remove pyrethroid insecticides (namely, fenvalerate, β-cyfluthrin, and tetramethrin) from water. The physical properties of the Fe3O4@ZIF-8@SiO2 nanoparticles were characterized via scanning electron microscopy, elemental mapping, energy-dispersive X-ray spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, inductively coupled plasma spectroscopy, thermogravimetric analysis, Brunauer–Emmett–Teller surface area analysis, dispersion analysis, and vibrating sample magnetometry. The prepared Fe3O4@ZIF-8@SiO2 nanoparticles exhibited excellent adsorption performance and high dispersibility and could be rapidly separated from water using an external magnetic field. The Fe3O4@ZIF-8@SiO2 nanoparticles exhibited the strongest adsorption effect at an adsorbent dosage of 10 mg, an adsorption time of 40 min, and a pH of 7. The fitted model for the adsorption process was consistent with the proposed secondary kinetic model and Sips isotherm model. The Fe3O4@ZIF-8@SiO2 nanoparticles exhibited maximum adsorption capacities of 316.23, 364.43, and 258.69 mg g–1 for fenvalerate, β-cyfluthrin, and tetramethrin, respectively. The Fe3O4@ZIF-8@SiO2 nanoparticles retained most of their adsorption capacity after five reuse cycles when acetone was used as an eluent for desorption. The mechanisms involved in the adsorption process included π–π stacking interactions, hydrogen bonds, hydrophobic interactions, and pore filling effects. This study provides a potential design for rapidly recoverable and reusable nanoparticles that can be used to effectively adsorb pyrethroid insecticides in wastewater.

A simple and efficient method for determining the pyrethroid pesticide residues in freshly squeezed fruit juices using a water stable metal–organic framework

A simple and efficient method was developed to assay-four common pyrethroid pesticides in freshly squeezed fruit juices. In this method, the water stable metal–organic framework UiO-66 was employed as the sorbent to directly extract the pesticides from freshly squeezed fruit juices for its good hydrophilicity to liposoluble pesticides. The pesticides could be captured by UiO-66 within 2 min under optimized conditions. The linearity of the pure solvent and matrix calibration curves were both satisfied (0.9961 ∼ 0.9998), and the matrix effect could be neglected. The limits of detection and limits of quantitation were 0.8 ∼ 1.5 and 2.9 ∼ 4.6 ng/g, respectively, which were much lower than the maximum residue levels (MRLs) set by the government (10 ∼ 5000 ng/g). The average recoveries of these pesticides were 68.1 ∼ 119.7 %, and the intra-day and inter-day relative standard deviations for recoveries were 5.2 ∼ 14.8 %. Thus, the developed method is reliable and can be used to evaluate the pyrethroid pesticide residues in freshly squeezed fruit juices..

A Schiff base networks coated stir bar for sorptive extraction of pyrethroid pesticide residues in tobacco

Schiff base networks (SNWs) were introduced as a new stir bar coating, and a method of SNWs- coated stir bar sorptive extraction (SBSE) coupled to high performance liquid chromatography-ultraviolet detector (HPLC-UV) was developed for determination of pyrethroid pesticide residues in tobacco. The prepared amorphous SNWs polymer from melamine and 3,5-dihydroxybenzaldehyde riches in triazine rings, hydroxyl groups and amino groups, and the SNWs/polydimethylsiloxane (PDMS) stir bar prepared by sol-gel method can extract weakly polar pyrethroid pesticides through hydrophobic, π-π and hydrogen bonding. The SNWs/PDMS stir bar exhibited high extraction efficiency toward pyrethroid pesticides (70–76%) and good mechanical stability with reused time more than 50 times. Under the optimal experimental conditions, the limits of detection were 0.20 - 0.66 µg/L with relative standard deviation varying in the range of 2.3–8.2%, which meets the requirements of trace analysis of pesticide residues in the tobacco industry. The method was applied to the determination of six pyrethroid pesticides in cigarette samples, and the recovery for the spiked samples ranged from 82 to 117%, showing a great applicability for the analysis of pesticide residues in real samples with a complex sample matrix.

Detection and risk associated with organochlorine, organophosphorus, pyrethroid and carbamate pesticide residues in chicken muscle and organ meats in Jordan

The aims of this study were to: i) analyze the prevalence and concentration of pesticides belonging to 4 major classes, namely organochlorines, organophosphates, carbamates and pyrethroids in chicken meat, liver and kidney; ii) evaluate the impact of boiling, frying and freezing on pesticide levels in chicken meat, and iii) estimate the dietary exposure to pesticide residues in chicken meat and conduct a risk assessment. Liquid chromatography-mass spectrophotometry (LC – MS/MS) was used to determine the concentrations of pesticide residues in samples. A total of 300 domestic (local) and imported samples were collected from the marketplace in Jordan. About 2.3%, 48.3%, 83%, and 46.3% of the samples exceeded MRLs for the organochlorine, organophosphorus, carbamate and pyrethroid pesticide groups, respectively. About 90% of the local and imported muscle samples and almost all the local and imported liver samples contained one or more pesticide above the MRL. Among all the samples tested, two pesticides, namely deltamethrin and fenoxycarb, occurred in high concentrations. Domestic samples were observed to have higher concentrations of pesticides compared to their imported counterparts. The pesticides concentrations decreased by about 50, 75 and 15% after boiling, frying and freezing, respectively. Risk assessment has shown that there is no potential risk from consuming chicken meat, however, local chicken meat is of more concern than is imported product. This study will help food control authorities develop appropriate regulations regarding the use of pesticides in Jordan.

Temperature-responsive deep eutectic solvent as eco-friendly and recyclable media for the rapid assessment of pyrethroid pesticide residues in surface soil sample

In the modern agricultural model, more and more attention has been paid to green production and sustainable agriculture practices. In this study, a simple and eco-friendly extraction method for the rapid assessment of nine different pyrethroid pesticides in surface soil samples was developed by the temperature-responsive deep eutectic solvent-based ultrasound assisted extraction. Three different temperature-responsive deep eutectic solvent systems of various classes were prepared to extract pyrethroid pesticides from spiked soil samples. The total spiked recovery displayed that temperature-responsive deep eutectic solvent composed of ethanolamine and o-cresol with molar ratio 1:1 was the optimum extraction solvent for temperature-responsive deep eutectic solvent-based ultrasound assisted extraction procedure. Based on Box-Behnken Design, the maximum extraction recovery (%) of total pyrethroid pesticides was 94.23% under the following conditions: extraction temperature of 68 °C, extraction time of 35 min, and solid–liquid ratio of 21 mg/mL. Meaningfully, the extraction recovery of pyrethroid pesticides was still more than 80% after fifth cycles of temperature-responsive deep eutectic solvent, demonstrating that temperature-responsive deep eutectic solvent could be repeatedly used. The detection results of actual soil samples indicated that the pyrethroid pesticide residues (8.42–28.72 μg/kg) in vineyard region were the most serious, which may be due to the high incidence of insect pests and the abuse of pesticides. The temperature-responsive deep eutectic solvent-based ultrasound assisted extraction method with the advantages of fast, trace, and high efficiency could be successfully applied to pyrethroid pesticide residues analysis in surface soil samples.

Modified QuEChERS method based on multi-walled carbon nanotubes coupled with gas chromatography-tandem mass spectrometry for the detection of 10 pyrethroid pesticide residues in tea

利用多壁碳纳米管(MWCNTs)QuEChERS法提取茶叶中拟除虫菊酯类残留农药,采用气相色谱-串联质谱(GC-MS/MS)分析测定,建立了一种灵敏度高、可靠性强的茶叶中农药残留检测方法。比较了单壁碳纳米管(SWCNTs)、MWCNTS、氨基化多壁碳纳米管和石墨烯4种碳纳米材料和其不同用量下的净化效果;采用正交试验设计对前处理最佳实验条件进行筛选,并对实验影响因素进行方差分析。结果表明:提取溶剂、碳纳米材料种类对10种拟除虫菊酯类农药回收率的影响具有极显著统计学差异(p<0.001),提取时间对回收率的影响有统计学差异(p<0.05),碳纳米材料用量对回收率影响不显著(p>0.05);最佳样品前处理条件为以乙腈为提取溶剂,超声提取35 min,净化剂为60 mg MWCNTs、200 mg PSA和200 mg C18。方法学考察表明,10种拟除虫菊酯类农药在0.01~2 mg/L范围内线性良好;检出限(LOD)为0.001~0.01 mg/kg,定量限(LOQ)为0.005~0.04 mg/kg;绿茶样品空白基质加标试验中,10种农药的回收率为91.4%~109.7%,相对标准偏差为0.12%~9.80%(n=6)。对花茶、绿茶、红茶3种茶叶基质进行基质效应(ME)评价,结果发现净化剂中加入MWCNTs在绿茶和红茶基质中能有效降低ME。利用该方法检测了市售120份茶叶中拟除虫菊酯类农药的残留,多个样品中检出目标物,但均未超标。该方法检测灵敏度高,可靠性好,具有良好的回收率和稳定性,能满足茶叶中农药残留快速定量分析的要求。

Detection of Pyrethroids in Food by Immunofluorescence Enhanced Method Based on Three-Layer Core-Shell Structure Upconversion Materials.

A novel rare earth upconversion nanomaterial with a three-layer sandwich core–shell structure was synthesized by an improved thermal decomposition method, and the morphology, fluorescence intensity and diffraction peak position of the new material were characterized by TEM (transmission electron microscope), XRD (Powder X-ray diffraction)and fluorescence spectrophotometer. The inert core/active shell/inert shell design improved the upconversion luminous efficiency of the new material several times. FTIR (Fourier transform infrared spectroscopy)characterization showed that the surface of activated upconversion nanoparticles was modified with silicon shell and amino group. Combined with the characteristics that aminoated polystyrene magnetic microspheres could be separated by the magnetic field, an upconversion magnetic separation immunoassay method for the detection of pyrethroid pesticide residues was established. The capture probe competed with the pyrethroid standard, combined the signal probe, and measured the fluorescence signal value formed by the capture probe signal probe complex at 542 nm under 980 nm excitation light. The LOD (limit of detection)of fenpropathrin was 0.01 μg/L, cypermethrin was 0.015 μg/L, and fenvalerate was 0.011 μg/L. Through the actual sample detection of apple, cabbage and other samples, the recovery rate of pyrethroids was between 83.4~97.8%. The comparison with the HPLC (high performance liquid chromatography)detection results showed that the established method had good accuracy, and could realize the quantitative analysis of pyrethroids in food.

Research and Application of In Situ Sample-Processing Methods for Rapid Simultaneous Detection of Pyrethroid Pesticides in Vegetables

A novel rapid and cost-effective pre-processing method for the simultaneous determination of pyrethroid pesticides in vegetables has been developed and validated. The process of pesticide extraction was carried out by the QuEChERS (quick, easy, cheap, effective, rugged and safe) method combined with filtration by filter paper, and cleanup was carried out by the multi-plug-filtration-cleanup (m-PFC) method with no centrifuge program during the whole process. The pre-processing method is optimized for gas chromatography (GC). The process is convenient and time saving, requiring just a few seconds per sample. The recovery rate (70–120%), limit of detection (0.0001–0.007 mg/kg), precision (0.2–9.3%) and accuracy for each analyte were determined in 10 representative vegetables with good results. Finally, the feasibility of the developed method was further confirmed by the successful determination of pyrethroid-pesticide residues in pyrethroid-containing practical samples within the processing method coupled with thin-layer chromatography and a colloidal-gold test strip.

Pesticide residue levels in surface water, using a passive sampler and in the sediment along the littoral zone of Lake Ziway at selected sites

Diaion® HP-20 resin passive samplers deployed in water and sediment samples collected from Lake Ziway were analyzed for 30 organochlorine, organophosphorus, carboxamide, and pyrethroid pesticide residues. The samples were collected from purposely selected sampling stations in five sites on Lake Ziway. Levels of selected pesticides were determined by GC–MS/MS in all samples. p,p′DDE and boscalid residues were the only detected pesticides in sediment samples. Similarly, only metalaxyl and boscalid residues were recovered from HP-20 resins. The concentration of p,p′DDE and boscalid in sediment ranged from 0.66–7.23 and 0.1–15.26 ng g−1 dry weight respectively. The presence of p,p′DDE but no other metabolites of DDT in all sediment samples indicated that DDT residues in Ziway Lake were aged and probably originated from the weathered agricultural soils of the surrounding region. The highest level of boscalid was recorded at Site 2 (near the floriculture enterprises) both in sediment and in HP-20 resins with a mean concentration of 11.8 ng g−1 dw and 39.6 ng g−1 disk respectively. However, the concertation of metalaxyl was the highest in the HP-20 resins deployed at Site1 and Site 4 (near the intensive small-scale vegetable farm) with a mean concentration of 54.7 ng g−1 disk and 54.3 ng g−1 disk respectively. Generally, most sampling sites of p,p′DDE were found to have a moderate ecological risk based on levels specified in the sediment quality standards. Moreover, the relatively high boscalid and metalaxyl levels in HP-20 deployed in Lake Ziway would be the result of recent intensive pesticide use by floriculture enterprises and small-scale vegetable farmers in the region. A spatial variation on the accumulation of detected pesticides among the sampling sites depends on the anthropogenic activities, around the lake from the point and non-point sources. Although most of the analyzed pesticides were below the detectable limit, further studies and continued monitoring of currently used pesticide residues in the Lake are highly recommended.

Method Development and Validation of Seven Pyrethroid Insecticides in Tea and Vegetable by Modified QuEChERS and HPLC-MS/MS.

This study developed a quick, easy, cheap, effective, rugged, and safe (QuEChERS) procedure for determining seven pyrethroid pesticide residues in tea, cucumber, and tomato via high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The overall average recoveries of the seven pyrethroids were 72%-104% (relative standard deviation (RSD); 2.0%-16.1%, 89%-109% (RSD; 0.7%-17.3%), 82%-110% (RSD; 1.6%-17.1%) for tea, cucumber and tomato, respectively. The determination coefficient (R2), the limit of detection (LOD), and the limit of quantification (LOQ) were ≥ 0.99, 0.007-1.875μgkg-1, and 0.025-6.250μgkg-1, respectively. The method was successfully used to monitor the pyrethroid pesticide residues in market samples. HPLC-MS/MS rapidly, sensitively, and accurately determined the pyrethroid pesticide residues.

Monitoring some pyrethroid pesticides residues in raw cow’s and buffalo’s milk

Monitoring some pyrethroid pesticides residues in raw cow’s and buffalo’s milk