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This work evaluates the factors affecting the presence of organochlorine pesticides in Pampeano aquifer in the Quequén Grande River watershed, Buenos Aires Province, Argentina. Eighteen sampling sites were selected in order to have representatives of different type of wells and types of soil. Among the analyzed compounds, endosulfan showed the highest concentrations (4.75 ng l− 1 mean), which could be related to use in the recent past. Others important pesticides groups detected were HCHs (1.1 ng l− 1 mean) and heptachlors (2.17 ng l− 1mean). The analysis of the results show that the thickness of the unsaturated zone is the main factor related to the concentrations of pesticides and there were no differences according to wells or soil types. Although agricultural use of most OCPs has been banned in Argentina from more than 30 years ago, their residues are still detected in groundwater of the region, indicating their high persistence. [ABSTRACT FROM AUTHOR]

Uptake characteristics of endosulfan (ED), including α-, β-isomers and sulfate-metabolites, from the soils by carrot and potato plants were investigated to establish a method that may be used to calculate recommended permissible soil contaminant concentrations ( C s, permissible ) at time of planting so that maximum residue level (MRL) standards are not exceeded. The residues of ED were analyzed in soils treated with ED at concentrations of either 2 or 10 mg kg soil −1 and in the plants (carrots and potatoes) grown in such soils for 60–90 d. Presence of plants increased ED dissipation rates in soils in patterns that were best fit to a double-exponential decay model ( R 2 of 0.84–0.99). The ED uptake extent varied with type of crop, ED isomer, plant growth duration, and plant compartments. However, ED concentrations in all edible parts of crops eventually exceeded their maximum residue limits. Total ED bioconcentration factor ( BCF ), the ratio of soil ED concentration at planting time to that in edible part of each crop at harvest day, was found to decrease with time due to decreasing soil ED concentration and increasing plant biomass in a pattern that followed a first order kinetic model. Using this model, the C s, permissible values, specific to the soils used in this study, were calculated to be 0.32 and 0.19 mg kg soil −1 for carrots and potatoes, respectively. The results and methods developed in this study may be utilized as a prediction tool to ensure crop safety from pesticide residues. [ABSTRACT FROM AUTHOR]

Microcantilever-based immunosensor is a next-generation electromechanical technique with broad application in biological detection. In this paper, we reported a microcantilever-based immunosensor that quantitatively detect the carbofuran, by using monoclonal antibodies to carbofuran as the receptor molecules. The surface of gold-coated microcantilever was chemically modified by the crosslinking of l -cysteine ( l -cys)/glutaraldehyde (GA). The monoclonal antibodies to carbofuran were then immobilized on the side of the microcantilever to fabricate the immunosensor, the mechanical bending induced by antigen-antibody specific binding under an experimental environment. Under the optimized conditions, immunosensor detected carbofuran showed a good linear relationship over the range from 1.0 × 10 −7 to 1.0 × 10 −3 g/L (R = 0.998), with a detection limit of 0.1 ng/mL. Moreover, the proposed immunosensor exhibited high sensitivity, specificity and good stability and can be successfully applied in the carbofuran determination in soil and vegetable samples with satisfactory results. [ABSTRACT FROM AUTHOR]

In this study, a rapid and sensitive method was developed for determining fenamidone and propamocarb hydrochloride residues in vegetables and soil by ultra-performance liquid chromatography-tandem mass spectrometry. The dissipation dynamics of fenamidone and propamocarb hydrochloride in pepper and soil was investigated in Beijing, Henan and Shandong provinces. The target compounds were extracted with methanol and cleaned with dispersive solid phase extraction using primary secondary amine. Two pairs of precursor product ion transitions for fenamidone and propamocarb hydrochloride were measured and evaluated. Average recoveries of fenamidone in potato, tomato, cabbage, pepper and soil at three levels (10, 100 and 1000 μg kg−1) ranged from 76.91% to 107.31% with relative standard deviations (RSDs) from 2.74% to 10.87% (n = 15). The average recoveries of propamocarb hydrochloride ranged from 74.84% to 97.96% with RSDs from 2.43% to 16.16% (n = 15). The limits of detection (LODs) for fenamidone in each matrix were 0.131–0.291 μg kg−1, and the limits of quantification (LOQs) were 0.436–0.970 μg kg−1. The LODs for propamocarb hydrochloride were 0.125–0.633 μg kg−1, and the LOQs were 0.417–2.11 μg kg−1. The results also showed that the dissipation of fenamidone and propamocarb hydrochloride in pepper and soil followed first-order kinetics model more than that of bi-exponential models. The half-lives of propamocarb hydrochloride were 6.90–15.78 days in pepper and 13.56–23.02 days in soil. The half-lives of fenamidone were 7.48–11.29 days in pepper and 35.18–42.78 days in soil. [ABSTRACT FROM AUTHOR]

Evaluation of the field scale agricultural non-point source (NPS) simulation model against field experimental data is an important step that must be considered before a model can be used as a management tool. Therefore, the present study focuses on the testing of two NPS models known as the RZWQM (Root Zone Water Quality Model) and the PESTFADE (PESTicide Fate And Dynamics in the Environment). These models are used to predict the soil water content, metribuzin fate, and transport in a sprinkler-irrigated soybean field located at the experimental farm of the Asian Institute of Technology (AIT) in the Pathumthani Province, Thailand. Field soil water content and metribuzin residue adsorbed at soil profile depths of 0–10, 10–20, and 30–40 cm at different time periods were intensively measured by the gravimetric method and Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS), respectively. When comparing the field measured data, it was observed that the RZWQM performed better in simulating the soil water fcontent, whereas the performance of the PESTFADE model was better at simulating the metribuzin residue in the soil. Specifically, a reasonable agreement existed between the measured soil water content and that predicted by the RZWQM for 0–10 and 30–40 cm soil depths. The model slightly overpredicted the metribuzin residue at 0–10 cm soil depth one day after herbicide application, whereas the prediction of metribuzin residue at 10–20 and 30–40 cm soil depths was in accordance with the measured values. The PESTFADE model performed relatively well in simulating the soil water content at 10–20 cm and metribuzin residue concentration at 0–10 and 10–20 cm soil profile depths. However, the model performed relatively poorly at 30–40 cm soil profile depth. These results indicate that when properly calibrated, both the RZWQM and PESTFADE models can be used to predict the movement of water and metribuzin residue in the soil of tropical zones. [ABSTRACT FROM AUTHOR]

Human health and the health of the environment have entwined. In this paper we underpin this position by presenting a modeling approach named CombiSimilarity, which has been developed by the first author in the software tool PyHasse comprising a wide variety of partial ordering tools. A case study of 18 Organochlorine Pesticides (OCPs) detected in soil as well as in human breast milk samples in the Taurus Mountains in Turkey is carried out. Seven soil samples and 44 breast milk samples were measured. We seek to answer the question whether the contamination pattern in breast milk is associated with the contamination pattern in soil by studying the mutual quantitative relationships of the chemicals involved. We could demonstrate that there is a similarity with respect to the concentration profiles between the soil and breast milk pollution. Therefore the hypothesis may be formulated that the concentrations of chemicals in the milk samples are strongly related to the soil contamination. This supports the concept that soil could be a surrogate for human exposure at background locations. [Copyright &y& Elsevier]

Terrestrial ecotoxicological tests are powerful tools for assessing the ecological risks that pesticides pose to soil invertebrates, but they are rarely used to evaluate seed dressing pesticides. This study investigated the effects of seed dressing pesticides on survival and reproduction of Folsomia candida (Collembola), using standardized ecotoxicological tests (after ISO guidelines with few adaptations for tropical conditions). Commercial formulations of five seed dressing pesticides were tested individually in Tropical Artificial Soil (TAS): the insecticides imidacloprid, fipronil, thiametoxam, and the fungicides captan and carboxin+thiram. Thiametoxam, captan, and carboxin+thiram were only lethal to F. candida at the highest concentration tested (1000mg of active ingredient kg−1 of dry soil). Imidacloprid and fipronil were lethal at lower concentrations (100 and 10mg a.i. kg−1 soil d.w, respectively), however, these concentrations were much higher than those predicted (PEC) for soil. Imidacloprid and fipronil were the most toxic pesticides in both tests, reducing significantly collembolan reproduction (EC20=0.02 and 0.12mga.i.kg−1 soil d.w, respectively). Further studies under more realistic conditions are needed, since imidacloprid and fipronil reduced collembolan reproduction at concentrations below or close to their respective PECs. [Copyright &y& Elsevier]

The dynamic flux of an organophosphate and four pyrethroid pesticides was determined in an air-(soil)-water-sediment system based on monitoring data from Guangzhou, China. The total air–water flux, including air–water gaseous exchange and atmospheric deposition, showed deposition from air to water for chlorpyrifos, bifenthrin and cypermethrin, but volatilization for lambda-cyhalothrin and permethrin. The transport of the pesticides from overlying water to sediment suggested that sediment acted as a sink for the pesticides. Additionally, distinct annual atmospheric depositional fluxes between legacy and current-use pesticides suggested the role of consumer usage in their transport throughout the system. Finally, pesticide toxicity was estimated from annual air–water-sediment flux within an urban stream in Guangzhou. A dynamic flux-based risk assessment indicated that inter-compartmental transport of chlorpyrifos decreased its atmospheric exposure, but had little influence on its aquatic toxicity. Instead, water-to-sediment transport of pyrethroids increased their sediment toxicity, which was supported by previously reported toxicity data. [Copyright &y& Elsevier]

The present study aimed to assess the environmental fate of the insecticide and nematicide ethoprophos in the soil–water interface following the pesticide application in simulated maize and potato crops under Mediterranean agricultural conditions, particularly of irrigation. Focus was given to the soil–water transfer pathways (leaching and runoff), to the pesticide transport in soil between pesticide application (crop row) and non-application areas (between crop rows), as well as to toxic effects of the various matrices on terrestrial and aquatic biota. A semi-field methodology mimicking a “worst-case” ethoprophos application (twice the recommended dosage for maize and potato crops: 100% concentration v/v) in agricultural field situations was used, in order to mimic a possible misuse by the farmer under realistic conditions. A rainfall was simulated under a slope of 20° for both crop-based scenarios. Soil and water samples were collected for the analysis of pesticide residues. Ecotoxicity of soil and aquatic samples was assessed by performing lethal and sublethal bioassays with organisms from different trophic levels: the collembolan Folsomia candida, the earthworm Eisenia andrei and the cladoceran Daphnia magna. Although the majority of ethoprophos sorbed to the soil application area, pesticide concentrations were detected in all water matrices illustrating pesticide transfer pathways of water contamination between environmental compartments. Leaching to groundwater proved to be an important transfer pathway of ethoprophos under both crop-based scenarios, as it resulted in high pesticide concentration in leachates from Maize (130µgL−1) and Potato (630µgL−1) crop scenarios, respectively. Ethoprophos application at the Potato crop scenario caused more toxic effects on terrestrial and aquatic biota than at the Maize scenario at the recommended dosage and lower concentrations. In both crop-based scenarios, ethoprophos moved with the irrigation water flow to the soil between the crop rows where no pesticide was applied, causing toxic effects on terrestrial organisms. The two simulated agricultural crop-based scenarios had the merit to illustrate the importance of transfer pathways of pesticides from soil to groundwater through leaching and from crop rows to the surrounding soil areas in a soil–water interface environment, which is representative for irrigated agricultural crops under Mediterranean conditions. [Copyright &y& Elsevier]

Pesticide residue is of concern as an environmental pollutant when present at medium to high concentrations. Such residue was quantified in both vegetable and soil samples by an enzyme inhibition technique. The multistep reactions were integrated into centrifugal microfluidic devices allowing automated simultaneous analysis of several samples or of replicates. The small sample size inherent to microfluidic devices allowed for less reagent to be used including less of the expensive enzyme which is key to this method. Liquid--solid magnetically actuated extraction, filtration, sedimentation, and detection were all integrated on the same device. Several parameters were optimized including the concentration of enzyme, substrate, chromatic agent, and reaction time. In this environmental application of centrifugal microfluidics, the percent inhibition of enzyme activity is logarithmically proportional to the demonstration pesticide concentration (in this case carbofuran). This meant that as the pesticide concentration increased in the samples, the reaction was more inhibited and the final product absorbed less light at 525 nm. Two versions of the centrifugal microfluidic devices were made. One version was designed for the analysis of vegetable samples (cabbage) and the other for the analysis of soil samples. Each version provided results that were statistically similar to the conventional benchtop method with a carbofuran limit of detection of 0.1 ppm or 0.1 µg g-1 (5 ng absolute limit of detection). [ABSTRACT FROM AUTHOR]

Pentachloronitrobenzene (PCNB) is a fungicide belonging to the organochlorine family and used extensively in agriculture for crop production. Many studies have implied that PCNB has become an environmental concern due to its widespread contamination in eco-systems. However, whether PCNB is bioaccumulated, degraded and phytotoxic in plants is poorly understood. In this study, several alfalfa (Medicago sativa) cultivars were grown in soil with PCNB to investigate their absorption and catabolism, including PCNB residues in the soil and PCNB-induced toxic responses in plants. Alfalfa plants varied widely in their ability to accumulate and degrade PCNB. The degradation rate of PCNB was 66.26–77.68% after alfalfa growth in the soils for 20 d, while the rates in the control (soil without alfalfa) were only 48.42%. Moreover, concentrations of PCNB residues in the rhizosphere soil were significantly higher than those in the non-rhizosphere soils. Alfalfa exposed to 10 mg kg−1 PCNB showed inhibited growth and oxidative damage, but the effects of PCNB on the cultivars differed significantly, indicating that the alfalfa cultivars have different tolerance to PCNB. Activities of invertase (INV), urease (URE), polyphenol oxidase (PPO), alkaline phosphatase (ALP) and acid phosphatase (ACP) were assayed in the treated soils and showed that the enzyme activities were altered after PCNB exposure. The URE, PPO, ALP and ACP activities were increased in soil following the planting of alfalfa. The objective of the study was to analyze the potential of different cultivars of alfalfa to accumulate and degrade PCNB from the contaminated soil. [Copyright &y& Elsevier]

Octanol–air partition coefficients (K OA) for 7 organochlorine pesticides (OCPs) were determined as a function of temperature using the GC retention time method. Log K OA values at 25 °C ranged over two orders of magnitude, between 8.32 (chlorpyrifos) and 10.48 (methoxychlor). The determined K OA values were within a factor of 0.5 (endosulfan sulfate) to 7.9 (endrin aldehyde) for values calculated as the ratio of octanol–water partition coefficient to dimensionless Henry's law constant. The internal energies of phase transfer between octanol and air (ΔU OA) ranged between 71.8 and 95.4 kJ mol−1 and they were within the reported range for OCPs (55.8–105 kJ mol−1). Atmospheric and soil OCP concentrations were also measured in Izmir, Turkey, and data used to investigate the soil–air gas exchange. Net soil–air gas exchange fluxes of OCPs ranged from −0.01 (volatilization, cis-nonachlor) to 56.4 ng m−2 day−1 (deposition, chlorpyrifos) in winter, while in summer they ranged from −0.03 (trans-nonachlor) to 329 ng m−2 day−1 (endosulfan I). In both sampling periods, endosulfan I and II, trans-nonachlor, p,p′-DDD and p,p′-DDT were generally deposited to the soil while γ-HCH and heptachlor epoxide mostly volatilized. Fluxes of other OCPs were variable (volatilization or absorption) due to their largely fluctuating ambient air concentrations. Calculated dry deposition and recently measured wet deposition fluxes were used to estimate the relative importance of different mechanisms (i.e., dry deposition, wet deposition, gas absorption, and volatilization) to the local soil pollutant inventory. Generally, all mechanisms contributed significantly to the soil OCP inventory. Volatilization fluxes were generally much lower than the sum of input fluxes (dry deposition, wet deposition and gas absorption) for most of the OCPs indicating a net deposition to the soil. [Copyright &y& Elsevier]

A simple, accurate and highly sensitive analytical method was developed in this study for determining the residues and dissipation dynamics of mepiquat chloride in soil and cotton crops (including plant and seed). The samples in this method were directly extracted with methanol–ammonium acetate solution and followed by analysis of high performance liquid chromatography tandem mass spectrometry (HPLC–MS/MS). The intra-day and inter-day recoveries of mepiquat chloride were in the range of 76.58–98.87 percent and 73.48–104.7 percent with relative standard deviations (RSDs) of 0.89–5.04 percent and 3.84–10.7 percent, respectively. The limit of quantification (LOQ) was 0.05mgkg−1 for soil and 0.1mgkg−1 for cotton plant and seed. The half-life of mepiquat chloride in cotton plants and in soil was 2.51–3.85 days and 7.56–10.50 days, respectively. The final residues of mepiquat chloride in all cotton seeds were below the MRLs of EU (5mgkg−1), Japan and America (2mgkg−1) over 14 days after the last spraying, and were below 1mgkg−1 (the MRLs set by Argentina and Australia) over 21 days after the last spraying at recommended dosage. The final residues in soil were below the LOD (0.01mgkg−1) over 21 days after the last spraying. [Copyright &y& Elsevier]

There are limited data on persistent organic pollutants (POPs) in the soils of the Tibetan Plateau. This paper presents data from a survey of organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in 40 background surface (0–5 cm) soils of the Tibetan Plateau. Soil concentrations (pg/g, dw) ranged as follows: DDTs, 13-7700; HCHs, 64-847; HCB, 24-564; sum of 15 PCBs, 75-1021; and sum of 9 PBDEs, below detection limit −27. Soil DDT, HCB, PCB and PBDE concentrations were strongly influenced by soil organic carbon content. HCH concentrations were clearly associated with the proximity to source regions in south Asia. The air–soil equilibrium status of POPs suggested the Tibetan soils may be partial “secondary sources” of HCB, low molecular weight PCBs and HCHs and will likely continue to be “sinks” for the less volatile DDE and DDT. [Copyright &y& Elsevier]

We evaluated the response of soil bacteria to applications of the insecticide teflubenzuron at the field rate dosage (FR; 0.15 mg/kg of soil) and at a higher dosage (10*FR; 1.5 mg/kg of soil). When applied at the FR dosage, teflubenzuron had no effect on several biochemical parameters of the soil, including substrate-induced respiration (SIR), dehydrogenase (DHA) and phosphatase activities (PHOS), and N–NO3 − and N–NH4 + concentrations. Additionally, no differences were observed in the culturable fraction of the soil bacteria (the number of heterotrophic, nitrifying, denitrifying and N2-fixing bacteria; the growth strategy; the ecophysiological and colony development indices; and the physiological state). In contrast, treatment with the 10*FR dosage of the insecticide significantly increased SIR, DHA, PHOS and N–NH4 + levels and the number of heterotrophic and denitrifying bacteria. Decreases in urease activity (URE) and the number of nitrifying and N2-fixing bacteria were also observed. A phospholipid fatty acid (PLFA) method-based analysis of the entire soil microorganism population revealed that teflubenzuron treatment affected the total fatty acid level as well as those considered to be of Gram-positive bacteria, Gram-negative bacteria and fungi. This effect was observed on days 1 and 14 post-treatment. A principal component analysis (PCA) of the PLFAs showed that teflubenzuron treatment significantly shifted the microbial community structure; however, all of the observed effects were transient. Studies on the degradation of teflubenzuron revealed that this process is characterised by a short lag phase and a rate constant (k) of 0.020/day. This degradation rate follows first-order kinetics, and the DT50 was 33.5 days. This is the first study that thoroughly examines the functional and structural status of both the culturable and non-culturable fractions of the soil microbial community after teflubenzuron application. [Copyright &y& Elsevier]

Formation of soil nonextractable residues (NER) is central to the fate and persistence of pesticides. To investigate pools and extent of NER formation, an established inverse modeling approach for pesticide soil degradation time series was evaluated with a Monte Carlo Markov Chain (MCMC) sampling procedure. It was found that only half of 73 pesticide degradation time series from a homogeneous soil source allowed for well-behaved identification of kinetic parameters with a four-pool model containing a parent compound, a metabolite, a volatile, and a NER pool. A subsequent simulation indeed confirmed distinct parameter combinations of low identifiability. Taking the resulting uncertainties into account, several conclusions regarding NER formation and its impact on persistence assessment could nonetheless be drawn. First, rate constants for transformation of parent compounds to metabolites were correlated to those for transformation of parent compounds to NER, leading to degradation half-lives (DegT50) typically not being larger than disappearance half-lives (DT50) by more than a factor of 2. Second, estimated rate constants were used to evaluate NER formation over time. This showed that NER formation, particularly through the metabolite pool, may be grossly underestimated when using standard incubation periods. It further showed that amounts and uncertainties in (i) total NER, (ii) NER formed from the parent pool, and (iii) NER formed from the metabolite pool vary considerably among data sets at t→∞, with no clear dominance between (ii) and (iii). However, compounds containing aromatic amine moieties were found to form significantly more total NER when extrapolating to t→∞ than the other compounds studied. Overall, our study stresses the general need for assessing uncertainties, identifiability issues, and resulting biases when using inverse modeling of degradation time series for evaluating persistence and NER formation. [ABSTRACT FROM AUTHOR]

Chinese Gridded Pesticide Emission and Residue Model was applied to simulate long-term environmental fate of β-HCH in Asia spanning 1948-2009. The model captured well the spatiotemporal variation of β-HCH soil concentrations across the model domain. β-HCH use in different areas within the model domain was simulated respectively to assess the influence of the different sources of β-HCH on its environment fate. A mass center of soil residue (MCSR) was introduced and used to explore environmental factors contributing to the spatiotemporal variation of β-HCH soil residue. Results demonstrate that the primary emission dominates β-HCH soil residues during the use of this pesticide. After phase-out of the pesticide in 1999, the change in β-HCH soil residues has been associated with the Asian summer monsoon, featured by northward displacement of the MCSR. The displacement from several major sources in China and northeastern Asia shows a downward trend at a 95% confidence level, largely caused by environmental degradation and northward delivery of β-HCH under cold condition in northern area. The MCSRs away from the India and southern and southeastern Asia sources show a rapid northward displacement at a 99% confidence level, featuring the cold trapping effect of the Tibetan Plateau. [ABSTRACT FROM AUTHOR]

The fate of the 14C-labeled herbicides ethidimuron (ETD), methabenzthiazuron (MBT), and the fungicide anilazine (ANI) in soils was evaluated after long-term aging (9–17 years) in field based lysimeters subject to crop rotation. Analysis of residual 14C activity in the soils revealed 19% (ETD soil; 0–10 cm depth), 35% (MBT soil; 0–30), and 43% (ANI soil; 0–30) of the total initially applied. Accelerated solvent extraction yielded 90% (ETD soil), 26% (MBT soil), and 41% (ANI soil) of residual pesticide 14C activity in the samples. LC-MS/MS analysis revealed the parent compounds ETD and MBT, accounting for 3% and 2% of applied active ingredient in the soil layer, as well as dihydroxy-anilazine as the primary ANI metabolite. The results for ETD and MBT were matching with values obtained from samples of a 12 year old field plot experiment. The data demonstrate the long-term persistence of these pesticides in soils based on outdoor trials. [Copyright &y& Elsevier]

A simple analytical method based on QuEChERs was established for diafenthiuron residues in pakchoi and soil. The residue levels and dissipation rates of diafenthiuron in pakchoi and soil were detected by HPLC–MS. And ultrasonic extraction was employed in the study to improve extraction effectiveness. At three fortification levels of 0.02, 0.1 and 1mg/kg in pakchoi and soil, recoveries were in the range 74.0 percent–100 percent, with relative standard deviations (RSD) of 6.1–14.8 percent. The limit of quantification (LOQ) of method was 0.02mg/kg for pakchoi and soil. In the supervised field trials, the half-lives of diafenthiuron in pakchoi and soil were 1.27 and 5.94 day, respectively. The final residue levels of diafenthiuron could not be detected in soil, while only trace amount of diafenthiuron residues were detected in pakchoi. [Copyright &y& Elsevier]

The analytical method for the residues of chlorpyrifos in rice plants, water and soil was developed and dissipation of chlorpyrifos under field conditions was studied. The limit of detection (LOD) of chlorpyrifos was 0.006mgkg−1 and the limit of quantification (LOQ) was found to be 0.04mgkg−1 in rice plant (water) and 0.02mgkg−1 in the other substrates, respectively. The results showed that the initial residues of chlorpyrifos in Nanjing and Guangxi were 4.99 and 6.05mgkg−1 (rice plant), 1.35 and 1.58mgkg−1 (water) and 0.51 and 0.63mgkg−1 (soil), respectively. The half-lives of chlorpyrifos in rice plant, water and soil from Nanjing were 4.28, 0.58 and 1.35 day, respectively, and the half-lives of those from Guangxi were 3.86, 0.52 and 1.21 day, respectively. The husked rice, rice hull and straw samples were found to contain chlorpyrifos well below the maximum residue limit (MRL) following the recommended dosage, the residues of chlorpyrifos in soil were undetectable under all application levels and frequencies after 28 day of applications. [Copyright &y& Elsevier]

A LC-ESI-MS/MS method with QuEChERS for analysis of emamectin benzoate in cabbage, apple and soil was established. At fortification levels of 0.001, 0.01 and 0.1mg/kg in cabbage, apple and soil, it was shown that recoveries ranged from 75.9 to 97.0 percent with relative standard deviation (RSD) of 4.4–19.0 percent. The limit of quantification (LOQ) was 0.001mg/kg for cabbage, apple and soil. The dissipation half-lives of emamectin benzoate in cabbage, apple and soil were 1.34–1.72 day, 2.75–3.09 day and 1.89–4.89 day, respectively. The final residues of emamectin benzoate ranged from 0.001 to 0.052mg/kg in cabbages, 0.003 to 0.090mg/kg in apples and 0.001 to 0.089mg/kg in soils, respectively. Therefore, it would be unlikely to cause health problems if emamectin benzoate was applied according to the use pattern suggested by the manufactures on the label. [Copyright &y& Elsevier]

A modified QuEChERS–LC–MS/MS (acronym of quick, easy, cheap, effective, rugged and safe-liquid chromatography tandem mass spectrometry) method for the analysis of pyraclostrobin residue in peanut and soil was developed and validated. Pyraclostrobin residue dynamics and final residues in supervised field trials at Good Agricultural Practice (GAP) conditions in peanut and soil were studied. The limits of quantitation (LOQs) for pyraclostrobin in soil, plant, shell and peanut samples were 0.00057, 0.00026, 0.003 and 0.0037mgkg−1, respectively. At fortification levels of 0.005, 0.05 and 0.5mgkg−1 in all samples, it was shown that recoveries ranged from 80.3% to 109.4% with relative standard deviations of 1.1–8.2% (n=5). The dissipation experiments showed the half-lives (T 1/2) of pyraclostrobin in soil and plants were 13.1–16.5 days and 10.3–11.2 days, respectively. At pre-harvest intervals (PHI) of 14, 21 and 28 days, pyraclostrobin residue were 0.005–0.20mgkg−1 in soil, 0.006–0.27mgkg−1 in plants, below 0.053mgkg−1 in shells and not detectable in peanuts. [Copyright &y& Elsevier]

Flubendiamide is a new insecticide that has been found to give excellent control of lepidopterous pests of tomato. This study has been undertaken to develop an improved method for analysis of flubendiamide and its metabolite des-iodo flubendiamide and determine residue retention in tomato and soil. The analytical method developed involved extraction of flubendiamide and its metabolite des-iodo flubendiamide with acetonitrile, liquid-liquid partitioning into hexane-ethyl acetate mixture (6:4, v v-1) and cleanup with activated neutral alumina. Finally the residues were dissolved in gradient high pressure liquid chromatography (HPLC) grade acetonitrile for analysis by HPLC. The mobile phase, acetonitrile-water at 60:40 (v v-1) proportion and the wavelength of 235 nm gave maximum peak resolution. Using the above method and HPLC parameters described, nearly 100 % recovery of both insecticides were obtained. There was no matrix interference and the limit of quantification (LOQ) of the method was 0.01 mg kg-1. Initial residue deposits of flubendiamide on field-treated tomato from treatments@48 and 96 g active ingredient hectare-1 were 0.83 and 1.68 mg kg-1,respectively. The residues of flubendiamide dissipated at the half-life of 3.9 and 4.4 days from treatments @ 48 and 96 g a.i. ha-1, respectively and persisted for 15 days from both the treatments. Des-iodo flubendiamide was not detected in tomato fruits at any time during the study period. Residues of flubendiamide and des-iodo flubendiamide in soil from treatment @ 48 and 96 g a.i. ha-1 were below detectable level (BDL, < 0.01 mg kg-1) after 20 days. Flubendiamide completely dissipated from tomato within 20 days when the 480 SC formulation was applied at doses recommended for protection against lepidopterous pests. [ABSTRACT FROM AUTHOR]