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Journal of Chromatography. B,... Sep 2020Organophosphate, carbamate and pyrethroid pesticides are the most common insecticides used worldwide. They may cause chronic poisoning in farmers and acute poisoning in...
Organophosphate, carbamate and pyrethroid pesticides are the most common insecticides used worldwide. They may cause chronic poisoning in farmers and acute poisoning in homicidal or suicidal cases. The determination of trace levels of these pesticides in human blood and urine is very challenging. This study focuses on a simultaneous quantitation method that was developed and validated for multi-class nine pesticides belonging to organophosphate, carbamate and pyrethroid classes in human blood and urine. Target pesticides were extracted from blood and urine using a modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) extraction method. Capillary column DB-35 ms (15 m × 0.25 mm, 0.25 µm) was used for chromatography with a 0.079 ml/min flow rate of carrier gas at constant pressure mode. Quantitation of sulfotep, phorate, carbofuran, chlorpyriphos, profenophos, triazophos, pyriproxyfen, lambda-cyhalothrin and permethrin was performed by mass spectrometer equipped with electron impact ionization source using selected ion monitoring (SIM) mode. The lower and upper limits of quantitation for all nine pesticides were 0.01 mg/L and 2.0 mg/dL respectively. The proposed method was proved to be simple, fast, sensitive, and robust. It has been applied to the analysis of 9 pesticides samples.
Topics: Gas Chromatography-Mass Spectrometry; Gastrointestinal Contents; Humans; Limit of Detection; Linear Models; Liquid-Liquid Extraction; Pesticide Residues; Pesticides; Reproducibility of Results
PubMed: 32603923
DOI: 10.1016/j.jchromb.2020.122227 -
Journal of Nematology 2020Easter lily bulbs for greenhouse forcing are produced in Del Norte County, California and Curry County, Oregon, USA. infestation seriously affects growth of field grown...
Easter lily bulbs for greenhouse forcing are produced in Del Norte County, California and Curry County, Oregon, USA. infestation seriously affects growth of field grown bulbs. During two consecutive years of field trials containing 22 treatments, commercially prepared formulations of essential oils (EOs) were compared to an untreated control and to a standard chemical fumigant treatment (FU) (1,3-dichloropropene and metam sodium) applied preplant followed by phorate (PH) at planting to determine their value in the management of lesion nematode, and in improving plant health. The EO products Duogard, EF400, EF300, and Cinnamite were tested as preplant dips to bulblet planting stock. The treated bulblets were tested either alone, in combination with PH at-planting, at planting following FU or in combination with PH at planting following FU. The organophosphates ethoprop and fosthiazate were also tested either alone, or at a reduced rate in combination with a reduced rate of PH. With respect to bulb circumference, ten treatments consistently outperformed the control. In consecutive years, three treatments had healthier looking roots than the control. At harvest, levels of lesion nematode within roots were consistently lower in nine treatments. EOs were beneficial in mitigating nematode damage. Easter lily bulbs for greenhouse forcing are produced in Del Norte County, California and Curry County, Oregon, USA. infestation seriously affects growth of field grown bulbs. During two consecutive years of field trials containing 22 treatments, commercially prepared formulations of essential oils (EOs) were compared to an untreated control and to a standard chemical fumigant treatment (FU) (1,3-dichloropropene and metam sodium) applied preplant followed by phorate (PH) at planting to determine their value in the management of lesion nematode, and in improving plant health. The EO products Duogard, EF400, EF300, and Cinnamite were tested as preplant dips to bulblet planting stock. The treated bulblets were tested either alone, in combination with PH at-planting, at planting following FU or in combination with PH at planting following FU. The organophosphates ethoprop and fosthiazate were also tested either alone, or at a reduced rate in combination with a reduced rate of PH. With respect to bulb circumference, ten treatments consistently outperformed the control. In consecutive years, three treatments had healthier looking roots than the control. At harvest, levels of lesion nematode within roots were consistently lower in nine treatments. EOs were beneficial in mitigating nematode damage.
PubMed: 32180376
DOI: 10.21307/jofnem-2020-010 -
The Science of the Total Environment May 2020The rate constants of carbonate radical anion (CO) reaction with organic molecules, mainly of environmental interest, were collected from the literature and structure... (Review)
Review
The rate constants of carbonate radical anion (CO) reaction with organic molecules, mainly of environmental interest, were collected from the literature and structure effects were discussed together with methods of rate constant determination and reaction mechanisms. These rate constants are essential for modelling chemical processes taking place with participation of reactive radicals in the environment determining the persistence of certain toxic compounds. The rate constants span over a very wide range from 10 to 10 mol dm s, but, even the highest values are smaller by a factor of 2-5 as the diffusion controlled limit. This survey shows that only those molecules have high rate constants in the 10-10 mol dm s range which have special electron rich part(s). These molecules are removed selectively in CO reactions. Such electron rich moiety is the NH group attached to an aromatic ring. High vales were measured e.g., for most of anilines or the sulfonamide antibiotics. -CO group attached to the N-atom (in acetanilides and in phenylurea herbicides), or strong electron withdrawing substituents on benzene ring strongly decrease the rate constant. High values were also measured for aromatic molecules with dissociated -OH group (O, phenoxides). The thioether group (e.g., in amino acids, or in fenthion or phorate insecticides) also activates the molecules in CO reactions.
PubMed: 32084688
DOI: 10.1016/j.scitotenv.2020.137219 -
Pest Management Science Aug 2020Multiple-herbicide resistance in Lolium rigidum and other weed species is increasingly exerting pressure on herbicide discovery research for solutions against...
BACKGROUND
Multiple-herbicide resistance in Lolium rigidum and other weed species is increasingly exerting pressure on herbicide discovery research for solutions against resistance-prone weeds. In this study we investigate: (i) the responses of L. rigidum populations and wheat to the new herbicide cinmethylin in comparison with other pre-emergence herbicides, (ii) the effect of seed burial depths on cinmethylin efficacy and crop selectivity, and (iii) the basis of cinmethylin selectivity in wheat.
RESULTS
Cinmethylin at 400 g ha controls herbicide-susceptible and multiple-resistant L. rigidum, with a reduction of >85% in plant emergence and 90% in aboveground biomass. Cinmethylin provides effective control of a large number of field populations of L. rigidum with evident resistance to trifluralin. When the wheat seed is buried ≥1 cm below the cinmethylin-treated soil surface, the emergence of crop seedlings is not different from the untreated control. The organophosphate insecticide phorate synergizes cinmethylin toxicity in wheat, with an LD of 682 g ha in the absence of phorate versus 109 g ha in the presence of phorate (84% reduction). The synergistic effect of phorate with cinmethylin on herbicide-susceptible L. rigidum appears smaller (a 44% reduction in the LD of cinmethylin).
CONCLUSIONS
Cinmethylin is effective in controlling multiple-resistant L. rigidum and appears safe for wheat when the seed is separated at depth from the herbicide applied to the soil surface. The basis of this metabolism-based selectivity is likely regulated by cytochrome P450 monooxygenases. © 2020 Society of Chemical Industry.
Topics: Herbicides; Lolium; Trifluralin; Triticum
PubMed: 32077583
DOI: 10.1002/ps.5798 -
Aquatic Toxicology (Amsterdam,... Apr 2020For decades, organophosphate (OP) insecticides have been used as chemical control agents in watersheds that support at-risk populations of Pacific salmon throughout...
For decades, organophosphate (OP) insecticides have been used as chemical control agents in watersheds that support at-risk populations of Pacific salmon throughout western North America. Spray drift, runoff, and other processes transport OPs to critical surface water habitats for migratory salmonids. While most OPs share a common mechanism of action (i.e., inhibition of neuronal acetylcholinesterase, or AChE), they typically vary in toxic potency. Moreover, dose-response relationships for exposure and sublethal neurotoxicity (e.g., brain AChE inhibition) in salmonids have not been defined for many OPs. Here we exposed juvenile coho salmon (Oncorhynchus kisutch) to five common anticholinesterase insecticides (dimethoate, ethoprop, naled, phorate and phosmet) that are widely used on agricultural, commercial, residential, and public lands. Each of the five pesticides produced a concentration-dependent inhibition of AChE enzyme activity. The effective concentration for 50 % AChE inhibition (96-hr EC) indicated the highest toxicity for phorate (EC = 0.57 μg/L) followed by phosmet (3.3 μg/L), naled (7.8 μg/L), ethoprop (90.6 μg/L) and dimethoate (273 μg/L). These findings can inform 1) relative hazard analyses for OP use near sensitive aquatic habitats, 2) predictions of sublethal OP mixture toxicity, and 3) ecological risk assessments for threatened or endangered species of Pacific salmon.
Topics: Acetylcholinesterase; Animals; Brain; Cholinesterase Inhibitors; Fisheries; Insecticides; Oncorhynchus kisutch; Organophosphorus Compounds; Washington; Water Pollutants, Chemical
PubMed: 32058876
DOI: 10.1016/j.aquatox.2020.105424 -
Plant Disease Apr 2020Tomato spotted wilt (TSW) is a common and serious disease of peanut ( L.) caused by (TSWV; family , genus ). Management frequently uses an integrated approach, with... (Meta-Analysis)
Meta-Analysis
Tomato spotted wilt (TSW) is a common and serious disease of peanut ( L.) caused by (TSWV; family , genus ). Management frequently uses an integrated approach, with cultivar resistance and application of in-furrow insecticide as two critical components. In-furrow insecticides help suppress thrips, which can injure and stunt young growing plants and transmit TSWV, with postemergent application of acephate capable of providing additional thrips control. To examine effects of systemic insecticides (imidacloprid, imidacloprid plus fluopyram, phorate, and acephate) on TSW management, yield, and economic return across cultivar susceptibilities (susceptible, moderately susceptible, and resistant) in South Carolina, a meta-analysis was used to synthesize results from 32 studies conducted between 2009 and 2018. Although efficacy and magnitude of individual treatments varied with susceptibility, imidacloprid increased, whereas phorate generally decreased TSW incidence relative to nontreated controls. In-furrow treatments followed by acephate further reduced TSW incidence and increased profitability. All examined treatments improved yield compared with untreated peanuts except for susceptible cultivars treated with imidacloprid. Imidacloprid plus fluopyram increased yield more than imidacloprid alone for the susceptible group, although there was little difference between these treatments in association with moderately susceptible cultivars. When comparing individual applications, phorate was overall the most profitable option across susceptibilities, although imidacloprid plus fluopyram exhibited analogous profitability for susceptible cultivars. Results from this study can be used to assist producer selection of management options for TSW in peanut.
Topics: Animals; Arachis; Insecticides; Solanum lycopersicum; Plant Diseases; South Carolina
PubMed: 32031909
DOI: 10.1094/PDIS-09-19-1829-RE -
Fa Yi Xue Za Zhi Dec 2019Objective To investigate the maximum allowable deviation of ion abundance ratios of characteristic fragment ions in common drugs (poisons) in blood by gas...
Objective To investigate the maximum allowable deviation of ion abundance ratios of characteristic fragment ions in common drugs (poisons) in blood by gas chromatography-mass spectrometry (GC-MS) method. Methods Four common drugs (poisons) (dichlorvos, phorate, diazepam and estazolam) were detected by GC-MS full scan mode after liquid-liquid extraction in two laboratories and under three chromatographic conditions. The deviations of ion abundance ratios of the four common drugs (poisons) in marked blood samples with concentrations of 0.5, 1.0, 2.0, 5.0 and 10.0 μg/mL were analyzed. At the same time, the false negative rates of ion abundance ratios were analyzed when the mass concentration was limit of detection (LOD), 2LOD, limit of quantitation (LOQ) and 2LOQ, and the false positive rates of ion abundance ratios were analyzed with blank blood samples. Results Under the two laboratories, four common drugs (poisons) and three kinds of chromatography conditions, the differences in deviations of the ion abundance ratios of marked blood samples were not statistically significant (>0.05). More than 95% of the absolute deviations of the ion abundance ratios of the marked blood samples were within the range of ±10%, and more than 95% of the relative deviations were within the range of ±25%. In cases of low concentration (concentration less than 2LOQ) or low signal to noise ratio (3-15), the false negative rate was less than 5% and the false positive rate was 0% when the relative deviation was greater than 50%. Conclusion The absolute deviations of ion abundance ratios of four common drugs (poisons) in marked blood samples are advised to have a determination range within ±10%, and the determination range of relative deviations within ±25%.
Topics: Gas Chromatography-Mass Spectrometry; Humans; Ions; Limit of Detection; Liquid-Liquid Extraction; Poisons
PubMed: 31970955
DOI: 10.12116/j.issn.1004-5619.2019.06.008 -
Mikrochimica Acta Dec 2019An aptasensor is described for electrochemical determination of organophosphorus pesticides (OPPs), specifically of profenofos, phorate, isocarbophos, and omethoate. The...
An aptasensor is described for electrochemical determination of organophosphorus pesticides (OPPs), specifically of profenofos, phorate, isocarbophos, and omethoate. The method uses a hairpin aptamer as signalling donor. Its 5' and 3' ends were modified with amino groups and the redox probe ferrocene (Fc), respectively. A nanocomposite consisting of graphene oxide and chitosan (GO-chit) was used to immobilize the aptamer via formation of an amide link. Its good conductivity facilitates monitoring of the electrochemical responses. Upon addition of an OPP, it will be bound by the aptamer. This results in an opening of the hairpin structure. Thus, Fc is shifted away from the surface of the electrode. As a result, the impedance increases and the redox signal of Fc decreases. The electrochemical performance, binding capacity and response of the aptasensor for profenofos, phorate, isocarbophos and omethoate were studied. The limits of detection are as low as 0.01, 0.1, 0.01 and 0.1 nM, respectively. Graphical abstract Schematic representation of an electrochemical aptasensor prepared by immobilizing ferrocene (Fc) labeled hairpin aptamer (HP) on the surface of graphene oxide-chitosan (GO-chit) modified electrode, and its application to the determination of organophosphorus pesticides (OPPs) by voltammetry.
Topics: Aptamers, Nucleotide; Biosensing Techniques; Chitosan; Electrochemical Techniques; Graphite; Molecular Structure; Organophosphorus Compounds; Particle Size; Pesticides; Surface Properties
PubMed: 31820139
DOI: 10.1007/s00604-019-4022-4 -
Saudi Journal of Biological Sciences Nov 2019Herein, we studied phorate for its toxicological effects in human lymphocytes. Phorate treatment for 3 h has induced significant increase in the lymphocytic DNA...
Herein, we studied phorate for its toxicological effects in human lymphocytes. Phorate treatment for 3 h has induced significant increase in the lymphocytic DNA damage. Compared to control, comet data from highest concentration of phorate (1000 µM) showed 8.03-fold increase in the Olive tail moment (OTM). Cytokinesis blocked micronucleus (CBMN) assay revealed 6.4-fold increase in binucleated micronucleated (BNMN) cells following the exposure with phorate (200 µM) for 24 h. The nuclear division index (NDI) in phorate (200 µM) treated cells reduced to 1.8 vis-à-vis control cells showed NDI of 1.94. Comparative to untreated control, 60.43% greater DCF fluorescence was quantitated in lymphocytes treated with phorate (500 µM), affirming reactive oxygen species (ROS) generation and oxidative stress. Flow cytometric data of phorate (200 µM) treated lymphocytes showed 81.77% decline in the fluorescence of rhodamine 123 (Rh123) dye, confirming the perturbation of mitochondrial membrane potential (Δ). Calf thymus DNA (ct-DNA) treated with phorate (1000 µM) exhibited 2.3-fold higher 8-Hydroxy-2'-deoxyguanosine (8-oxodG) DNA adduct formation, signified the oxidative DNA damage. The alkaline unwinding assay revealed 4.0 and 6.5 ct-DNA strand breaks when treated to phorate and phorate-Cu (II) complex. Overall, the data unequivocally suggests the cyto- and genotoxic potential of phorate in human lymphocytes, which may induce comparable toxicological consequences in persons occupationally or non-occupationally exposed to insecticide phorate.
PubMed: 31762602
DOI: 10.1016/j.sjbs.2019.04.008 -
Molecules (Basel, Switzerland) Jul 2019Pesticides vary in the level of poisonousness, while a conventional rapid test card only provides a general "absence or not" solution, which cannot identify the various...
Pesticides vary in the level of poisonousness, while a conventional rapid test card only provides a general "absence or not" solution, which cannot identify the various genera of pesticides. In order to solve this problem, we proposed a seven-layer paper-based microfluidic chip, integrating the enzyme acetylcholinesterase (AChE) and chromogenic reaction. It enables on-chip pesticide identification via a reflected light intensity spectrum in time-sequence according to the different reaction efficiencies of pesticide molecules and assures the optimum temperature for enzyme activity. After pretreatment of figures of reflected light intensity during the 15 min period, the figures mainly focused on the reflected light variations aroused by the enzyme inhibition assay, and thus, the linear discriminant analysis showed satisfying discrimination of imidacloprid (Y = -1.6525X - 139.7500), phorate (Y = -3.9689X - 483.0526), and avermectin (Y = -2.3617X - 28.3082). The correlation coefficients for these linearity curves were 0.9635, 0.8093, and 0.9094, respectively, with a 95% limit of agreement. Then, the avermectin class chemicals and real-world samples (i.e., lettuce and rice) were tested, which all showed feasible graphic results to distinguish all the chemicals. Therefore, it is feasible to distinguish the three tested kinds of pesticides by the changes in the reflected light spectrum in each min (15 min) via the proposed chip with a high level of automation and integration.
Topics: Cluster Analysis; Enzyme Inhibitors; Ivermectin; Lab-On-A-Chip Devices; Neonicotinoids; Nitro Compounds; Optics and Photonics; Paper; Pesticide Residues; Phorate; Time Factors
PubMed: 31269660
DOI: 10.3390/molecules24132428