Phenylureas monuron

Metolachlor 2-Chloro-N-[2-ethyl-6-methylphenyl]-N-[2-methoxy-l-methylethyl] acetamide atrazine 2-chloro-4-ethylamino-6-isopropylamino-j-triazine. Prometon 2,4-bis(isopropylamino)-6-methoxy-5-triazine. Cyanazine 2-[[4-chloro-6-(ethylamino)-5-triazin-2-yl]amino]-2-methylpropionitrile. Fenuron 1,1-dimethyl-3-phenylurea. Monuron l,l-dimethyl-3-(4-chlorophenyl)urea. Isotherms in water suspensions at room temperature unless otherwise indicated. Standard error of the slope. Assuming organic matter is twice the organic carbon. U.S. Environmental Protection Agency reference sediments. 

Following the earlier work of Kirkland [125] on phenylurea herbicides, Sidwell and Ruzicka [126] applied liquid chromatography to the identification and determination of active ingredient contents of phenylurea herbicide formulations. Smith and Lord [118] have used liquid chromatography for the determination of Chlorotoluron residues in soil, but Diuron and Monuron interfered in their chromatographic system. 

Fig. 7 Chromatograms obtained after the preconcentration of 50 ml of a diluted industrial effluent spiked at 1 pg L 1 with a mixture of triazines and phenylureas through a styrene-divinylbenzene (SDB) SPE cartridge (a) and through the terbutylazine MIP cartridge (b). Compounds (1) deethylatrazine (DEA), (2) monuron, (3) deethylterbutylazine (DET), (4) atrazine, (5) diuron, (6) terbutylazine, (7) neburon. UV detection at 220 nm [46]...

The first two derivatives in the series, monuron and metobromuron, are related to the 4-haloanilines. Their primary photochemistry has been studied by Boulkamh and Richard by means of nanosecond absorption spectroscopy [80]. The transients detected from both compounds in aqueous solution could be assigned to the N-substituted 4-iminocarbene, imino-p-benzoquinone-O-oxide and anilino radical from a complete analogy of their spectral and reactive behavior with that of the species obtained from 4-chloroaniline [55,57]. The quantum yields of carbene formation were determined to be = 0.051 for monuron and

halogen-substituted phenylurea derivatives underwent the same heterolytic dehalogenation process as the 4-haloanilines, which could be understood with reference to the protonability of the amine nitrogen, as in the case of 4-chloro-N,N-dimethylanilinc [55]. 

Fig. 1.33. Top the resolution window diagram for the gradieni-elulion separation of a mixture of twelve phenylurea herbicides on a Separon SGX Cix. 7.5 nm. column (150 x 3.3 mm i.d.) in dependence on the initial concentration of methanol in water at the start of the gradient, A. with optimum gradient volume Mg = 73 ml. Column plate number N =. 5000.. Sample compounds hydroxymetoxuron (/). desphenuron (2), phenuron (.1). metoxuron (4). monuron (5), monolinuron (6). chlorotoluron (7), metobromuron (X), diuron (9), linuron (/O), chlorobromuron (//). neburon U2). Bottom the separation of the twelve phenylurea herbicides with optimised binary gradient from 24 to l(X)9f methanol in water in 73 min. Flow rate I ml/min.

Pig. 9.12. (a) Principle of immunoaffinity solid-phase extraction, (b) An example of on-line immunotrapping and RP-HPLC of 13 phenylurea herbicides spiked into water. Analytes 1, phenuron 2, metoxuron 3, monuron 4, methabenzthiazuron 5, chlortoluron 6, fluomethuron 7, isoproturon 8, difenoxuron 9, buturon 10, Unuron 11, chlorbromuron 12, difluzbenzuron 13, neburon [65]. (Reprinted with permission.)... 

The appearance of ESI mass spectra depends on the solvent conditions, especially on the extent of sodium contamination. Sodiated molecules were observed as the base peak for chlortoluron, isoproturon, diuron, linuron, and diflubenzuron [34], while protonated molecules and only weak sodiated molecules were observed for monuron, diuron, and neburon [14], Some phenylureas can also be analysed in negative-ion ESI, where deprotonated molecules as well as acetate or formate adducts can be observed, depending on the mobile-phase composition [9],... 

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. 

Some carbamates (carbosulfan, benfuracarb, carbofuran, pirimicarb, diethofencarb, and diuron) and phenylurea pesticides (monuron and monolinuron) were sampled from different fruit juices by using 50-pm carbowax-templated resin (CW-TPR) and a 60-pm PDMS/DVB SPME fiber (Sagratini et al., 2007). The fiber desorption into the SPME-LC/MS interface chamber previously filled with 70% methanol and 30% water, was performed in static mode. 

Figure 9.4. Phenylurea pesticides and carbamates detected in wine by automated intube SPME and LC/ESI-MS analysis (Wu et al., 2002). (14) monuron, (15) fluome-turon, (16) siduron, (17) diuron, (18) linuron, (19) neburon, (20) propham, (21) chlorpropham, (22) barban, (23) promecarb (structures of carbaryl and methiocarb are reported in Figs. 9.1 and 9.11, respectively).

The most important substances of this group are l,l-dimethyl-3-phenylurea (fenuron, 5) 3-(4-chlorophenyl)-1,1-dimethylurea, (monuron, 6) 3-(3,4-dichlorophenyl)-1,1 -dimethylurea (diuron,7) 1,1 -dimethyl-3-(a,a,a-trifluoro-m-tolyl)urea (fluometuron, 8) l,l-dimethyl-3-( ,a,a-trifluoro-p-tolyl)urea (para-fluron, 9) 3-(3-chloro-/j-tolyl)-1,1-dimethylurea (chlortoluron, 10) 3-(3-chloro-4-methoxyphenyl)-l,l-dimethylurea (metoxuron, 11) 3-[(4-chlorophenoxy)phenyl]-... 

A number of other structural types of pesticides are/may be also of carcinogenicity concern. These include the biphenyl ethers, hydrazides, substituted phenylureas and substituted amino-s-triazines as represented by nitrofen (NCI Technical Report No. 26), daminozide (NCI Technical Report No. 83), monuron (NTP Technical Report No. 266) and propazine (see ref. 29),... 

FIGURE 25.9 Capillary GC with fused-silica column coated with CP-Sil 5 (analogous to SB 30 and OV-101) of HFB derivatives of 13 phenylureas obtained after extraction of a Bosbaan river water sample spiked at 1 fjig/ level, and direct derivatization with HFB A. Injected amount corresponds to 0.1 ng of each herbicide. Symbol explanation Fm, fluometuron Fe, fenuron Mo, monuron Ml, monolinuron Ip, isoproturon Ct, chlorotoluron Mb, metobromuron Bu, buturon Di, diuron Li, linuron Cb, chlorbromuron Mx, metoxuron Nb, neburon. (From Brinkman, U. A. Th., de Kok, A., and Geerdink, R. E., J. Chromatogr., 283, 113, 1984. With permisssion.)... 

FIGURE 25.20 SIM LC-ES/MS of an extract of 4 1 drinking water spiked with PUHs and their metabolites. Individual spike level 2 ng/1. MS data acquisition was performed by using 8 retention windows. Acronyms AA, aromatic amine M, metabolite PhU, partial or total dealkylated phenylurea herbicid IS, internal standard (monuron). (From Di Corcia, A., Costantino, A., Crescenzi, C., and Samperi, R., J. Chromatogr., 852, 465, 1999.)... 

The phenylureas were adsorbed in small amounts by anion and cation exchange resins (51) and in large amounts by charcoal 182, 381, 383). Yuen and Hilton (383) found that diuron and monuron adsorbed on charcoal was readily desorbed with water and that a surface active agent (type not specified) decreased adsorption. They suggested that this was evidence that the compounds were physically adsorbed, probably through van der Waals forces. 

Phenylamides. The phenylamide herbicide diphenamid (Table IX) probably behaves much like the acetanilides in aqueous and soil systems. The compound is moderately soluble, 260 ppm, and leaches much more readily in soils than the phenylurea herbicide linuron 371), Deli and Warren 384) also found that diphenamid was readily leached through several types of soil. Harris 151) found that diphenamid was moderate to high in its mobility in soil, falling between the phenylureas norea and monuron. Diphenamid moved more through course textured soils than... 

Apphcation of PBl to phenylurea pesticides [74, 92-94] and their chlorinated compounds such as diuron, Hnuron and monuron [95] in environmental samples allowed their determination in surface and drinking waters in underivatized form. An improvement in sensitivity for the determination of phenylurea and isocyanates was obtained with a post[Pg.754]

Volmer et al. studied phenylureas and sulfonylureas by TSP-LC-MS after sample concentration by Cjg SPE [175]. 15 phenylurea- and 1 thiourea pesticides besides 112 polar pesticides from other pesticide classes were examined by TSP ionisation, detection limits and TSP mass spectra of these polar compounds were presented [245], Besides other polar pesticides, the phenylurea pesticides isoproturon and diuron were on-line concentrated on a precolumn from several surface and drinking water samples and then determined by TSP-LC-MS [247]. A multi-residue TSP-LC-MS method was published by Moore et al. for the determination of the urea pesticides chlortoluron, diuron, isoproturon, and Unuron in water samples after Cig-SPE [248]. Ci8 Empore disks were applied to concentrate phenylureas from river water and spiked seawater samples prior to TSP-LC-MS. Detection limits of 2-20 (ig L and recoveries between 80 and 125% were observed [239]. TSP-LC-MS (SIM) in the positive mode allowed determination of the urea pesticides chlor-bromuron, diuron, linuron, metobromuron, monuron, neburon in apples, beans, lettuce, peppers, potatoes and tomatoes with detection limits of 0.025-1 ppm [255]. 20 other polar pesticides, linuron, which was under suspicion of being a dietary oncogenic risk (US Natl. Res. Council) was determined by TSP-LC-MS a single rapid procedure in vegetables with detection limits of 0.05-0.10 ppm [270]. TSP-LC-MS and ESI were used in a multi-residue method for determination of the sul-... 

Fig. 5 Top. The resolution window diagram for RP gradient elution separation of phenylurea herbicides on a Separon SGX C18 7.5 p,m column (150 X 3.3 mm I.D.) dependent on the initial concentration of methanol in water at the start of the gradient A with optimum gradient volume Vg — 73 ml. Column plate number N = 5000 sample compounds 1, hydroxymetoxuron 2, desphe-nuron 3, phenuron 4, metoxuron 5, monuron 6, monolinuron 7, chlorotoluron 8, metobromuron 9, diuron 10, linuron 11, chlor-obromuron and 12, neburon. Bottom. The separation with optimized binary gradient from 24% to 100% methanol in water in 73 min. Flow rate = 1 ml/min T = 40°C.

The separation of 12 phenylurea hebicides (metabenzthiazuron, fenuron, metoxuron, monuron, chlortoluron, fluometuron, isoproturon, diuron, chloroxuron, chlorbro-muron, buturon, neburon) extracted from drinking water was attempted on a base deactivated Cg column (2 = 245nm) using a 35/65 acetonitrile/water [10 mM... 

Figure 26 In situ positive-ion FAB-MS/MS analysis of the phenylurea herbicide monuron.

The use of herbicides that inhibit or interact with the photosynthetic machinery is seen, superficially, to be advantageous because of the likelihood of fewer problems of animal toxicity. However, the identical nature of the process in both crop and weed species, apart from C4 plants, means that herbicide selectivity must be achieved by differential uptake, movement, or metabolism. Following the discovery of the herbicidal action of N (4-chlorophenyl)-N,N-dimethylurea (subsequently known as CMU or monuron) by Bucha and Todd in 1951, Wessels and Van der Veen and Cooke showed that this compound was a potent inhibitor of photosynthetic electron transport. This, the first so-called Hill reaction inhibitor, was followed subsequently by numerous other phenylureas, triazines, uracils,... 

Turning to the substituted phenylureas, such as monuron (9) and diuron (10), JV-dealkylation features prominently in their metabolism in plants (Figure 10.5b). Whereas monodemethylated derivatives possess residual phytotoxicity, iV-didealkylation generally results in complete detoxification, as indicated by failure of such products to inhibit the Hill reaction of... 

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