Rapid Residue Analysis of Sulfonylurea Herbicides in Surface Water: Methodology and Residue Findings in eastern Tiaoxi River of China

A new method combining QuEChERS (quick, easy, cheap, effective, rugged and safe) and DLLME (dispersive liquid–liquid microextraction) for the simultaneous determination of residues of ten sulfonylurea herbicide in water using UPLC-MS/MS was developed and validated. Analytes were extracted and purified with QuEChERS and concentrated in chlorobenzene by applying the DLLME procedure. Several extraction parameters were tested, such as volume, extractive solvent by the QuEChERS method and subsequently used for DLLME, selection of extractive solvent and its volume, was tested. The developed method was validated on the basis of international guidelines. Mean recoveries ranged from 81.2 to 104.9%. Repeatability and reproducibility were lower than 10%. Limits of detection (LODs) and quantification (LOQs) were below 0.074 μg/L and 0.244 μg/L, respectively. Decision limit (CCα) and detection capability (CCβ) were calculated and CCβ ranged from 0.101 μg/L (pyrazosulfuron-ethyl) to 0.260 μg/L (nicosulfuron). Finally, when the method was applied to real samples, traces of three compounds were found in 42 samples and only thifensulfuon-methyl was detected above the LOQ in three samples at 0.17-0.20 μg/L.

Preparation of Ionic Liquid-immobilized HY Zeolite Catalysts and Application in the Synthesis of Propylene Carbonate

At first,NaY zeolite was modified to HY zeolite by ion exchange method,and then compound salt ion liquids were immobilized onto HY zeolite to prepare two immobilized ionic liquid catalysts HY-[HeMIM]Cl/(ZnBr_(2))_(2) and HY-[BMIM]Br/(ZnBr_(2))_(2).The synthesized immobilized ionic liquid catalysts were tested by FT-IR,XRD,TG and BET respectively.The results show that the prepared immobilized ionic liquids are the target product,have good thermal stability,and meet the requirements of catalysis.After immobilization,the intensity of crystallization peak is reduced,and the specific surface area becomes smaller.Conversion rate,selectivity and yield are as evaluation indicators to study the catalytic performance of immobilized ionic liquid catalysts for the synthesis of propylene carbonate from carbon dioxide and propylene oxide.Experimental results show that compound salt ion liquids were successfully immobilized on HY zeolite.Under the conditions of a temperature of 120℃,a pressure of 2.0 MPa,and a catalyst dosage of 2.0%,the catalytic effect of HY-[HeMIM]Cl/(ZnBr_(2))_(2) is better than HY-[BMIM]Br/(ZnBr_(2))_(2),and the conversion rate,selectivity and yield are 92.34%,98.87%and 91.30%.

Synthesis of Ethyl Methyl Carbonate Catalyzed by Immobilized Carboxylic Functionalized Ionic Liquids via Transesterification Reaction

The carboxylic functionalized ionic liquid was immobilized on the molecular sieve(MCM-22)and then applied in the catalytic synthe-sis of ethyl methyl carbonate(EMC)via transesterification of dimethyl carbonate(DMC)with ethanol.Combined characterization results of FT-IR,XRD and TG suggest that the ILs had been immobilized on molecular sieve MCM-22.The influences of reaction temperature,time,and the mass ratio of MCM-22-CPTES-MIL/Ca O have also been investigated in detail.The catalytic tests demonstrated that MCM-22-CPTES-MIL/Ca O could catalyze the transesterification of DMC and ethanol with high efficiency,superior to those results of the heterogeneous catalysts reported previously.

Operation analysis and parameter optimization of the conveying device for uniform crushed straw throwing and seed-sowing machines

Uniform crushed straw throwing and seed-sowing machines can achieve the processes of straw chopping,straw transport,sowing,fertilization,and straw mulching at the same time,which is widely used in many areas of China.Conveying device is one of the important components used to convey,elevate and throw straw.However,the problems of high power consumption and congestion affect the promotion of the machine.Therefore,the conveying device of uniform crushed straw throwing and seed-sowing machine was analyzed in order to determine its device operation mechanism.Kinematic and dynamic analyses of particles of crushed rice straw during lifting and dispersion are used to develop a flexible-body model of rod-shaped and agglomerate-shaped crushed straw and a coupling model including the mechanical structure of the device.By integrating computational fluid dynamics and the discrete element method,the gas-solid coupling theory in numerical simulations and motion analysis of crushed straw particles is used to determine how the flow field and motion characteristics affect the conveying performance.Besides,regression equations to describe the relationships between the factors and each assessment index were established by using the regression analysis and response surface analysis with the software Design-Expert.The effect of throwing blade speed X_(1),conveying volume of crushed straw X_(2),and pipeline diameter X_(3) on the throwing speed of crushed straw Y_(1) and specific power consumption Y2 were investigated.The highest throwing speed of crushed straw and lowest specific power consumption are the optimization goal.The results of optimization showed that the predict the best optimal parameters were 2000 r/min throwing blade rotational speed,1.4 kg/s conveying volume,and 220 mm pipeline diameter,the planter achieved a throwing speed of 12.2 m/s and specific power consumption of 9179 m^(2)/s^(2).And then a field test verification was conducted.The planter achieved a throwing speed 12.4 m/s and specific power consumption 9070 m^(2)/s^(2) while selecting the best optimal parameters.Thus,the optimal parameters can provide a high-performance operation and satisfy the actual operation requirements The results provide a theoretical basis and data support for seeding technology innovation and equipment optimization to ensure uniform crushed straw throwing in dense rice stubble fields.

Pollution level and human health risk assessment of some pesticides and polychlorinated biphenyls in Nantong of Southeast China

Food consumption is one of the key exposure routes of humans to contaminants. This article evaluated the residue levels of 51 pesticides and 16 polychlorinated biphenyls （PCBs） in selected fish and food items which were commonly consumed in the Nantong area of Jiangsu Province, Southeast China. The 51 pesticides and 16 PCBs were analyzed by highly sensitive gas chromatography- tandem mass spectrometry （GC-MS/MS）. The results showed that organochlorine pesticides such as dichlorodiphenyltrichloroethanes （DDTs）, hexachlorocyclohexanes （I-ICHs）, hexachlorobenzene （HCB） and mirex and other pesticides including chlorpyrifos, pyrethroid pesticides, metolachlor, pyridaben and trifluralin were frequently detected in the samples, which was consistent with the accumulation level and characteristics of these toxic chemicals in human adipose tissue of people living in Nantong. Meanwhile, correlation of the residue level of toxic chemicals with their physical chemical properties and historic use pattern in Nantong area was observed. Combined with dietary survey results at the same sampling locations, human health risk assessment of ingestion through the dietary route was performed. The results suggested that the non-cancer risks of the chemicals investigated can be considered negligible in the Nantong area, however, the cancer risks from lifetime dietary exposure to DDTs and HCB have exceeded the acceptable levels.

Using electrotopological state indices to model the depuration rates of polychlorinated biphenyls in mussels of Elliptio complanata

A quantitative structure-activity relationship （QSAR） model on depuration rate constants （ka） of polychlorinated biphenyls （PCBs） in freshwater mussel Elliptio complanata was successfully constructed using electrotopological state indices （ESI） and partial least squares （PLS） regression. The cross validated 2 Qcum and the correlation coefficient R for the model were determined to be 0.845 and 0.954, respectively. The satisfactory Q2cum and R values indicated significantly high robustness and good predictive ability for the model. The model was tested and found acceptable for the prediction of logkd （the logarithm of the deputation rate constants） by validation set. According to the model, an increase in the values of Saasc, S5＇, S4, S5 and S4＇, led to increased logkd, and a decrease in the values of Na, S2, and S6 also resulted in increased logkd. Among these descriptors, Ncl, S aasC, S5＇,, S4 and S5 made significant contributions to the value of logkd. These significant descriptors showed that the depuration of PCBs in Elliptio complanata may be mainly attributed to an equilibrium partitioning process among compartments with different lipid contents, while the reactivity of PCBs with enzymes or other molecules may play a subordinate role.

Influences of 1-methylcyclopropene-containing papers on the metabolisms of membrane lipids in Anxi persimmons during storage

Objectives:The aim of this work was to analyse the effects of 1-methylcyclopropene(1-MCP)treatment on the metabolisms of membrane lipids in postharvest Anxi persimmons during storage.Materials and methods:Anxi persimmon(Diospyros kaki L.f.cv.Anxi)fruits were treated by paper containing 1-MCP with a concentration of 1.35μl/l.The cellular membrane permeability was analysed by the electric conductivity meter.The activities of lipoxygenase(LOX),phospholipase(PLD)and lipase were determined by spectrophotometry.The component and relative amounts of membrane fatty acids were determined using gas chromatograph(GC).Results:The 1-MCP-treated Anxi persimmons manifested a lower electrolyte leakage rate,lower LOX,PLD and lipase activities,higher levels of unsaturated fatty acids(USFAs),higher ratio of USFAs to saturated fatty acids(SFAs)(U/S),higher index of USFAs(IUFA),but lower levels of SFAs.Conclusions:The degradation and the metabolisms of membrane lipids could be suppressed by 1-MCP treatment,which might be accountable for the delaying softening of postharvest Anxi persimmons during storage.

Paper-containing 1-methylcyclopropene treatment suppresses fruit decay of fresh Anxi persimmons by enhancing disease resistance

Objectives:The purpose of this work was to evaluate the potential application of papers containing 1-methylcyclopropene(1-MCP)postharvest treatment for suppressing fruit decay of fresh Anxi persimmons and its possible mechanism.Materials and methods:Anxi persimmon fruit were treated with papers containing 1-MCP at the dosage of 1.35μL/L and stored at(25±1)℃and 85 per cent relative humidity for 35 days.During storage,the fruit decay rate and lignin content were evaluated,and the content of total phenolics,the activities of phenylalanine ammonia lyase(PAL),polyphenol oxidase(PPO),peroxidase(POD),chitinase(CHI),and p-1,3-glucanase(GLU)were determined by spectrophotometry.Results:The 1-MCP-treated persimmons displayed a lower fruit decay rate,but higher contents of lignin and total phenolics,higher activities of PAL,PPO,POD,CHI,and GLU.Conclusions:The treatment with 1-MCP could inhibit the fruit decay of postharvest Anxi persimmons,which might be because 1-MCP enhanced fruit disease resistance by increasing the activities of disease resistance-associated enzymes and retaining higher contents of disease resistance-related substances in postharvest fresh Anxi persimmons.These findings indicate that papers containing 1-MCP at the dosage of 1.35μL/L have potential application in suppressing fruit decay and extending storage life of postharvest fresh Anxi persimmons.

Differential effects of Rho-kinase inhibitor and angiotensin Ⅱ type-1 receptor antagonist on the vascular function in hypertensive rats induced by chronic L-NAME treatment

Little attention has been paid to the effect of Rho-kinase inhibitor on the vascular dysfunction of nitric oxide-deficient hypertension.We aimed to investigate whether the Rho-kinase inhibitor fasudil showed beneficial effect on the vascular dysfunction of the N^(G)-nitro-L-arginine methyl ester(L-NAME)treated rat,as well as to compare the differential effects of fasudil and angiotensin Ⅱ receptor antagonist valsartan on vascular function.In the present study,both valsartan and fasudil exerted antihypertensive action on the L-NAME-treated rats,while only va lsartan attenuated the cardiac hypertrophy.Treatment with valsartan showed improvement on vascular reactivity to norepinephrine,KCl and CaCl_(2),whereas fasudil therapy showed little effect on vasoconstriction.Endothelium-dependent vasodilation to acetylcholine was reduced in the NO-deficient group but was normalized by the fasudil therapy.The increased expression of RhoA and Rho-kinase(ROCK)in the vasculature was corrected well to normal level by either valsartan or fasudil administration,which seemed to be at least partially responsi ble for the beneficial effect of the drug infusion.These findings suggest that the angiotensin Ⅱ receptor antagonist interferes more with the contractile response than Rho-kinase inhibitor,whereas inhibition of Rho-kinase activity exhibits a better improvement on vasorelaxation than blockade of angiotensin Ⅱ receptor.