Bifenox Research Articles

Study of the degradation of diphenyl-ether herbicides aclonifen and bifenox in different environmental waters

The degradation of the diphenyl-ether herbicides aclonifen (ACL) and bifenox (BF) in water samples has been studied under different laboratory conditions, using in-tube solid-phase microextraction (IT-SPME) coupled to capillary liquid chromatography (capLC). The working conditions were selected in order to detect also bifenox acid (BFA), a compound formed as a result of the hydroxylation of BF. Samples (4 mL) were processed without any previous treatment, which allowed the detection of the herbicides at low ppt levels. The effects of temperature, light and pH on the degradation of ACL and BF have been tested using standard solutions prepared in nanopure water. The effect of the sample matrix has been evaluated by analysing different environmental waters spiked with the herbicides, namely ditch water, river water and seawater. The kinetics of the degradation have been studied and the half-life times (t1/2) have been calculated. The results obtained have demonstrated that the sample matrix is the most important parameter affecting the degradation of the tested herbicides. The degradation of both ACL and BF was much faster in ditch and river water samples, where t1/2 values of only a few days were observed. However, both compounds showed a better stability in seawater samples, where they can persist for several months. In all matrices ACL was found to be more stable than BF. In samples where BF had been substantially degraded, BFA was also detected, although the stability of this compound was also limited. Other degradation products have been detected along the study.

Spectrofluorometric and computational approaches for the interaction studies of aclonifen and bifenox with human serum albumin

Interaction of two broadly used herbicides, aclonifen (ACF) and bifenox (BIF) with the major transporter in human circulation, human serum albumin (HSA) were examined using fluorescence and absorption spectral measurements combined with in silico analyses. Assessment of the fluorescence and absorption spectral results affirmed the complexation between ACF/BIF and HSA. Increase in the KSV value with temperature characterized the ACF/BIF-induced quenching of the protein fluorescence as dynamic quenching. The moderate binding affinities (Kf = 1.74×104 – 1.95×106 M−1 for ACF–HSA complex; Kf = 2.00×103 – 1.02×106 M−1 for BIF–HSA complex) were pointed out between ACF/BIF and HSA, showing a relatively higher binding constant values with increasing temperatures. Quantitative evaluation of thermodynamic data (ΔS = +0.86 kJ mol−1 K−1 and ΔH = +225.43 kJ mol−1 for ACF–HSA complex; ΔS = +1.11 kJ mol−1 K−1 and ΔH = +304.63 kJ mol−1 for BIF–HSA complex) predicted the contribution of hydrophobic interactions in the ACF–HSA and BIF–HSA association processes, which were well supported by our molecular docking results. In silico analyses were made to acquire insight details into the ACF and BIF binding to HSA at the binding sites and suggested the locations of ACF and BIF binding sites as both subdomain IIA (site I) and subdomain IIIA (site II) of HSA, showing more preference toward site I.

Determination of three diphenyl ether herbicides in rice by magnetic solid phase extraction using Fe<sub>3</sub>O<sub>4</sub>@MOF-808 coupled with high performance liquid chromatography

利用溶剂热法构筑了Fe3O4@MOF-808吸附剂,将其用于大米中除草醚(NIT)、乙氧氟草醚(OXY)和甲羧除草醚(BIF)3种二苯醚类除草剂的富集,结合高效液相色谱法,建立了大米中该类除草剂的分析方法。研究通过傅里叶变换红外光谱、X射线衍射仪、扫描电子显微镜以及振动样品磁强计对构筑的磁性吸附剂的结构、表面形貌及磁强度进行表征。表征结果显示,球形的Fe3O4纳米颗粒与八面体形貌的MOF-808成功复合,Fe3O4@MOF-808饱和磁化强度可达40.35 emu/g,可以满足磁性固相萃取的需求;对吸附剂用于大米中3种二苯醚类除草剂富集的磁性固相萃取条件(吸附剂用量、吸附时间、洗脱溶剂种类以及洗脱体积)进行了优化。优化结果显示,25 mg吸附剂在6 min内即可达到对目标物的完全吸附,洗脱溶剂采用0.5 mL×2的甲醇。在最优的磁性固相萃取条件下,结合高效液相色谱-紫外检测法,建立了大米中3种二苯醚类除草剂的分析方法。方法在2~300 μg/L范围内线性关系良好(r > 0.998), NIT、OXY、BIF的检出限和定量限依次为0.6、0.6、0.4 μg/kg和2.0、2.0、1.5 μg/kg,在5、10和20 μg/kg 3个加标水平下的回收率为87.3%~96.7%,相对标准偏差不超过10.8%,且富集因子在25~29之间。将所建方法用于大米中NIT、OXY、BIF的分析,各样品均未检出这3种二苯醚类除草剂。该方法具有操作简单、快速、准确的特点,适用于大米样品中除草剂的残留分析。

Simultaneous determination of bifenox, dichlobenil and diclofop methyl by hollow carbon nanospheres enhanced magnetic carboxylic multi-walled carbon nanotubes

A novel analytical method based on magnetic solid-phase extraction (MSPE) coupled with high performance liquid chromatography-diode array detection (HPLC-DAD) was established for three herbicides simultaneous determination. The key of the method was the explored extractant, which was a composite of hollow carbon nanospheres (HCSs) enhanced magnetic carboxylic MWCNTs (HCSs@Fe3O4-MWCNTs-COOH). MWCNTs-COOH was inserted in the pores of HCSs by oscillation and sonication with the capillary forces, making the carboxylic groups and structure intervals of the composite increase as compared to MWCNTs-COOH, therefore the extractant exhibited enhanced hydrophilicity, dispersibility, adsorptivity and selectivity. The extractant was sensitive to analytes with the structure of multi-aromatic ring, more hydrogen bond acceptor and large molecular polar surface area, which can be attributed to hydrogen bonding and π-π electron-donor-acceptor (EDA) interactions. The morphology, structure and magnetic property of the extractant were characterized. Then the explored extractant based MSPE-HPLC-DAD method was applied for bifenox (BFO), dichlobenil (DCB) and diclofop methyl (DCM) determination from wheat flour samples. Prior to real sample analysis, critical extraction parameters such as solution pH, extraction time, salt addition and temperature were investigated and optimized, and the analytical method was evaluated. It was indicated that the method had satisfactory linearities with the linear coefficients above 0.99, good precision with the RSD less than 3.5%, desirable recoveries ranged from 88.8% to 96.6%, and low limits of detection (LOD) that were 0.39, 0.24, and 0.68 ng/g for DCB, BFO and DCM, respectively. The established MSPE-HPLC-DAD method has great potentials for trace polar herbicides selective determination from complex matrix samples.

Electrochemical study of fenitrothion and bifenox and their simultaneous determination using multiwalled carbon nanotube modified glassy carbon electrode

Electrochemical behavior of fenitrothion (FT) and bifenox (BF) was investigated using cyclic voltammetry on the glassy carbon electrode. Cathodic peaks for the reduction of an Ar–NO2 group in both fenitrothine (o,o-dimethyl o-(3-methyl-4-nitrophenyl) phosphorothioate) (FT) and bifenox (methyl 5-(2,4-dichlorophenoxy)-2-nitrobenzoate) (BF) overlap strongly, and it is difficult to determine the compounds individually from their mixtures by these cathodic peaks. By an electrochemical irreversible reduction of Ar–NO2 in FT and BF it was transformed into a reversible redox couple (Ar–NHOH/Ar–NO) which can be used for simultaneous determination of fenitrothion (FT) and bifenox (BF) by square wave voltammetry (SWV). The experimental parameters, such as pH value, prepotential magnitude, time of the applied prepotential and pulse amplitude of SWs were optimized. To obtain better detection limit and sensitivity, the surface of the glassy carbon electrode was modified by a pretreated multi-walled carbon nanotube. Scanning electron microscopy (SEM) and square wave voltammetry (SWV) were used to characterize the performance and structure of the modified electrode. Under the optimized experimental conditions FT and BF give linear response over the range of 0.2–60.0μM. The detection limit for both FT and BF was found to be 0.08μM. The practical application of the modified electrode was demonstrated by measuring the concentration of FT and BF in river water samples.

Selection and Characterization of Protoporphyrinogen Oxidase Inhibiting Herbicide (S23142) Resistant Photomixotrophic Cultured Cells of Nicotiana tabacum

Summary S23142 and Acifluorfen-ethyl (AFE) inhibit protoporphyrinogen oxidase (Protox) and induce accumulation of protoporphyrin IX (Proto IX) which is a strong phytotoxic photosensitizer. A S23142-resistant cell line, YZI-1 S, of photomixotrophically cultured tobacco was selected and its resistance mechanism was characterized. While growth rates of wild-type and YZI-1 S cells were similar in the absence of the herbicide, S23142 concentrations that reduced the chlorophyll contents by 50 % were 2 and 250 nM for wild-type and YZI-1 S cell lines, respectively. The YZI-1 S cells also exhibited resistance for other types of Protox inhibiting herbicides (acifluorfenethyl, acif luorf en, bif enox, oxadiazon, chlomethoxynil, nitrof en and chloronitrofen), but were sensitive to atrazine and DCMU, which inhibit photosynthetic electron transport. YZI-1S cells did not accumulate Proto IX, even at 100nM S23142 in which the wild-type cells accumulated large amounts of Proto IX. Protox isolated from YZI-1S cells showed a 2-fold higher activity than that of wild-type cells and also exhibited a 20-fold increase in tolerance to S23142. On the other hand, treatment with 1 mM 6-Aminolevulinic acid (ALA), a tetrapyrrole precursor, induced photobleaching by accumulation of Proto IX in both YZI-1 S and wild-type cells under high light irradiation. From these results, we conclude that the resistance of YZI-1S cells to S23142 is due mainly to the increase of Protox activity.

Degradation of Bifenox, a biphenyl Ether Herbicide, Methyl 5-(2, 4-Dichlorophenoxy)-2-Nitrobenzoate, in Soils

ジフェニルエーテル系除草剤ビフェノックス [Modown®, methyl 5-(2,4-dichlorophenoxy)-2-nitrobenzoate] の土壌中における挙動を, 14C-ニトロベンゼン環およびジクロルベンゼン環標識化合物を用いて調べた. 14CO2の放出は非湛水土壌 (畑水分条件) ではかなり認められたが, 湛水土壌ではきわめて少なかった. 有機の揮散性物質は両水分条件とも認められなかった. 各種溶媒による抽出実験から, 分解の早い時期においては, ビフェノックスの分解物の土壌吸着形態は非共有結合的なものがかなり多くあるものと推定された. 殺菌土壌等, 数種の異なった分解条件での分解様式は, エステル結合の加水分解は主として微生物反応によるものであり, ニトロ基のアミノ基への還元は主として化学 (非生物) 反応によることを示唆した.