Pesticides diuron

A method for analysis of polar pesticides in wine by the use of automated in-tube SPME coupled with LC/ESI-MS was proposed (Wu et al., 2002). In-tube SPME is a microextraction and preconcentration technique that can be coupled on-line with high-performance liquid chromatography (HPLC), suitable for the analysis of less volatile and/ or thermally labile compounds. This technique uses a coated open tubular capillary as an SPME device and automated extraction. Using a polypyrrole coating, six phenylurea pesticides (diuron, fluometuron, linuron, monuron, neburon, siduron) and six carbamates (barban, car-baryl, chlorpropham, methiocarb, promecarb, propham) were analyzed in wine. Structures of compounds are reported in Fig. 9.4. Due to the high extraction efficiency of the fiber toward polar compounds, benzene compounds, and anionic species, LODs ranging between 0.01 and 1.2pg/L were achieved, even if the sample ethanol content affects the recoveries of analytes. 

The urea pesticides diuron, fluormeturon, neburon and Hnuron cited as potential groundwater contaminants from US EPA in the National Pesticide Survey were quantitatively determined by APCI-LC-MS(-t) [354]. APCI-LC-MS was also used to test for 46 pesticide compounds in shallow groundwater samples from two sandy and two clay catchment areas. Of the neutral polars observed, isopro-turon belonged to the most frequently found compound [351]. Sphid et al. described an APCI-LC-MS method for the determination of isoproturon and different types of pesticides and their degradation products in ground water samples. Detection Umits, recovery, precision and Hnearity data were reported [350]. 

It should be noted that tyrosinase can be inhibited by many different compounds such as carbamate and dithiocarbamate pesticides, diuron, atrazines, desisopropy-latrazine, chlorophenols, and thioureas. Based on this characteristic, tyrosinase has been used to develop enzymatic biosensors for the detection of many pesticides with a similar sensing mechanism with AChE and BChE (Fig. 11.4). Despite the... 

Urea hydrolysis is frequently observed as the initial reaction for pesticides having urea bonds, such as linuron, diuron, and chlorsulfuron (10) (eq. 14)... 

Although most nonionic organic chemicals are subject to low energy bonding mechanisms, sorption of phenyl- and other substituted-urea pesticides such as diuron to sod or sod components has been attributed to a variety of mechanisms, depending on the sorbent. The mechanisms include hydrophobic interactions, cation bridging, van der Waals forces, and charge-transfer complexes. 

A solvent free, fast and environmentally friendly near infrared-based methodology was developed for the determination and quality control of 11 pesticides in commercially available formulations. This methodology was based on the direct measurement of the diffuse reflectance spectra of solid samples inside glass vials and a multivariate calibration model to determine the active principle concentration in agrochemicals. The proposed PLS model was made using 11 known commercial and 22 doped samples (11 under and 11 over dosed) for calibration and 22 different formulations as the validation set. For Buprofezin, Chlorsulfuron, Cyromazine, Daminozide, Diuron and Iprodione determination, the information in the spectral range between 1618 and 2630 nm of the reflectance spectra was employed. On the other hand, for Bensulfuron, Fenoxycarb, Metalaxyl, Procymidone and Tricyclazole determination, the first order derivative spectra in the range between 1618 and 2630 nm was used. In both cases, a linear remove correction was applied. Mean accuracy errors between 0.5 and 3.1% were obtained for the validation set. 

Figure 5.2 Electrospray-MS-MS signal response of seven of the pesticides versus eluent flow rate, based on (a) peak area, and (b) peak height , atrazine , simazine , diuron x, isoproturon , chlorfenvinphos , chlorpyrifos O, alachlor. Reprinted from 7. Chromatogr., A, 937, Asperger, A., Efer, J., Koal, T. and Engewald, W., On the signal response of various pesticides in electrospray and atmospheric pressure chemical ionization depending on the flow rate of eluent applied in liquid chromatography-mass spectrometry , 65-72, Copyright (2001), with permission from Elsevier Science.

Comparison of the pesticide concentrations (ng/L) found in this study in sites HDCD and HD AD with those measured in a previous study performed in 2005 in the same sampling sites [ 16, 20] showed a general good agreement for all pesticides except for bentazone, MCPA, propanil, and atrazine, which presented now comparatively lower concentrations, and alachlor, malathion, diuron, and molinate, whose concentrations have increased considerably (Fig. 3). 

Pesticides containing methyl or other alkyl substituents maybe linked to N or 0 (i.e., N- or O-alkyl substitution). An N- or O-dealkylation catalyzed by microorganisms frequently results in loss of the pesticide activity. Phenylurea (see Chap. 1) becomes less active when microorganisms AT-demethylate the molecules (e. g., the conversion of Diuron to the normethyl derivative, Fig. 7). The subsequent removal of the second AT-methyl group renders the molecule fully nontoxic [169]. On the other hand, the microbial O-demethylation of Chloroneb creates the non-toxic product 2,5-dichloro-4-methoxyphenol (Fig. 7). 

Synonyms AF 101 AI3-614378 Anduron Ansaron Bioron BRN 2215168 Caswell No. 410 CCRIS 1012 Cekiuron Crisuron Dailon DCMU DCMU 99 Dialer Dichlorfenidim 3-(3,4-Di-chlorophenol)-l,l-dimethylurea 3-(3,4-Dichlorophenyl)-l,l-dimethylurea A -(3,4-Dichloro-phenyl)-A,A-dimethylurea l,l-Dimethyl-3-(3,4-dichlorophenyl)urea Dion Direx 4L Diurex Diurol DMU DP hardener 95 Duran Durashield Dynex EINECS 206-354-4 EPA pesticide chemical code 035505 Farmco diuron Herbatox HW 920 Karmex Karmex diuron herbicide Karmex DW Krovar Lucenit Marmer NA 2767 NSC 8950 Seduron Sup r flo Telvar Telvar diuron weed killer UN 2767 Unidron Urox D USAF P-7 USAF XR-42 Vonduron. 

The most ubiquitous pesticide was simazine, present in 80% of the samples, followed by atrazine, diuron, DEA and diazinon, present in more than 50% of the samples (64%, 56%, 56% and 50%, respectively). Cyanazine, molinate, fenitro-thion and mecoprop were detected in less than 5% of the samples. The maximum individual concentrations were observed for alachlor (9,950 ng/L in M33, 2008), dimethoate (2,277 ng/L in M35, 2010), DEA (1,370 ng/L in M48, 2007) and linuron (1,010 ng/L in M33, 2008), while many others, such as terbuthylazine, DIA, atrazine and metolachlor, presented levels also higher than 500 ng/L. Results are consistent when evaluated with the GUS index (see Table 2). Mots triazines and metolachlor, i.e., the compounds with GUS index > 3 and therefore with higher leaching potential, were among the most ubiquitous an abundant compounds. In contrast, fenitrothion, which according to its GUS index (0.64) is a nonlixiviable pesticide, was detected at low levels in less than 5% of the samples. 

SPE LC/MS/MS methods have been developed for the determination of polar pesticides (as propanyl, thiobencarb, diuron, simazine, bentazone etc.) and of their degradation products in waters with LOQ aronnd 25 ng L (Figure 18.1) [73], for the determination of chloroacetamide herbicides (LOD=25ng L ) [74], of sulfonylureas, bentazone, and phenoxyacids in river and drainage waters (LOD of the order of few ng L" ) [9]. 

Finally, in fourth place we find 2,4-D, which is used at a little over 1 million pounds per year. This is the first pesticide which we might normally think of when considering the most common pesticides. This is followed in 7th-10th positions by four other herbicides, Diuron, Vapam, Dinoseb, and Eptam. 

Ruepert and Ploeger [170] have described a procedure which allows the simultaneous determination of 22 pesticides (eg metamitron, simazine, diuron chlorpham) which is applicable to potable, ground and surface waters. The method relied on high performance... 

Extension Toxicology Network (EXTOXNET). 1996, June (revised). Diuron. Pesticide Information Profiles. A Pesticide Information Project of Cooperative Extension Offices of Cornell University, Oregon State University, the University of Idaho, and the University of California at Davis and the Institute for Environmental Toxicology, Michigan State University USDA/Extension Service/National Agricultural Pesticide Impact Assessment Program, http //extoxnet.orst.edu/pips/diuron.htm (accessed May 8, 2006). 

Maltby et al. (2002) and Van den Brink et al. (2006a) compared SSDs based on acute and chronic laboratory toxicity data for aquatic test species exposed to pesticides. The SSDs were constructed with toxicity data for the most sensitive taxonomic group, because of the specific toxic mode of action of the pesticides selected. The SSDs were used to calculate the hazardous concentration to 5% of the species (HC5) by means of a log-normal distribution model, and comparisons were performed for 2 insecticides and 7 herbicides (Table 6.4). The log-normal model did not fit the diuron (herbicide) short-term L(E)C50 data or the atrazine (herbicide) long-term NOEC data. Consequently, the L(E)C50 HC5 value for diuron and the NOEC HC5 value for atrazine should be interpreted with caution, as well as their acute HC5-chronic... 

Pesticide residues Acetochlor Alachlor Atrazine Carbendazin/Benomyl Cyclodienes, 2,4-D DDE Diuron Glyphosate Metolachlor Organophosphate/Carbamate Pyrethroids Spynosyn Surfactants Alkyl ethoxylate (AE) Alkylphenol ethoxylate (APE) Linear alkylbenzene sulfonate (LAS) Estrogens 17-B-Estradiol (E2) ... 

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