Application of microcolumn liquid chromatography-continuous-flow fast atom bombardment mass spectrometry in environmental studies of sulfonylurea herbicides

Reiser, R. W.; Barefoot, Aldos C.; Dietrich, Roland; Fogiel, Arthur J.; Johnson, Walter; Scott, Marcia S.

doi:10.1016/s0021-9673(01)88440-5

Cited by 47 publications

(26 citation statements)

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“…IdentiÐcation of the puriÐed chlorsulfuron hydrolysis products was achieved using micro-column liquid chromatography/ continuous-Ñow fast atom bombardment mass spectrometry. For detailed discussion of the methods employed, see Reiser et al 25 were placed in water-jacketed beakers under sterile conditions and covered with quartz lids to prevent evaporation and permit ultraviolet (UV) light transmission. The beakers were maintained at 25(^1)¡C and placed in natural sunlight in Wilmington, DE during the period 23 JuneÈ24 July 1989.…”

Section: Chlorsulfuronmentioning

confidence: 99%

Fate of chlorsulfuron in the environment. 1. Laboratory evaluations

Strek

1998

Pestic. Sci.

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:The behaviour and fate of chlorsulfuron in aqueous and soil systems were examined in laboratory studies. Aqueous hydrolysis was pH-dependent and followed pseudo-Ðrst-order degradation kinetics at 25¡C, with faster hydrolysis occurring at pH 5 (half-life 24 days) than at either pH 7 or 9 (half-lives [365 days). Degradation occurred primarily by cleavage of the sulfonylurea bridge to form the major metabolites chlorobenzenesulfonamide (2-chlorobenzenesulfonamide) and triazine amine (4-methoxy-6-methyl-1,3,5-triazin-2-amine). This route is a major degradation pathway in water and soil systems. Aqueous photolysis (corrected for hydrolysis) proceeded much more slowly (half-life 198 days) than aqueous hydrolysis and is not expected to contribute signiÐ-cantly to overall degradation. Hydrolysis in soil thin-layer plates exposed to light (half-life 80 days), however, progressed at a much faster rate than in dark controls (half life 130 days), which suggests that a mechanism other than direct photolysis may have been operative. An aerobic soil metabolism study (25¡C) in a Keyport silt loam soil (pH 6É4, 2É8% OM) showed that degradation was rapid (half-life 20 days). Dissipation in an anaerobic sediment/water system (initial pH of water phase 6É7, Ðnal pH 7É4) progressed much more slowly (half-life [365 days) than in aerobic soil systems. Major degradation products in aerobic soil included the chlorobenzenesulfonamide and triazine amine as in the aqueous hydrolysis study. Neither of these degradation products exhibited phytotoxicity to a variety of crop and weed species in a glasshouse experiment, and both exhibited an acute toxicological proÐle similar to that of chlorsulfuron in a battery of standard tests. Demethylation of the 4-methoxy group on the triazine moiety and subsequent cleavage of the triazine ring is another pathway found in both aqueous solution and soils, though di †erent bonds on the triazine amine appear to be cleaved in the two systems. Hydroxylation of the benzenesulfonamide moiety is a minor degradation pathway found in soils. Two soils amended with 0É1 and 1É0 mg kg~1 chlorsulfuron showed slight stimulation of nitriÐcation. The 1É0 mg kg~1 concentration of chlorsulfuron resulted in minor stimulation and inhibition of 14C-cellulose and 14C-protein degradation, respectively, in the same soils. Batch equilibrium adsorption studies conducted on four soils showed that adsorption was low in this system 13È54). Soil thin-layer (K oc chromatography of chlorsulfuron and its major degradation products demon-(R f \ 0É55È0É86) strated that the chlorobenzenesulfonamide had slightly less mobility and that the (R f \ 0É34È0É68) triazine amine was much less mobile than chlorsulfuron. In an aged column (R f \ 0É035È0É40) leaching study, subsamples of a Fallsington sandy loam 5É6, OM 1É4%) or a Flanagan silt (pH water loam 6É4, OM 4É0%) were treated with chlorsulfuron, aged moist for 30 days in a glass-(pH water house and then placed upon a prewet column of the same soil type prior to initiation of leaching....

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Section: Chlorsulfuronmentioning

confidence: 99%

Fate of chlorsulfuron in the environment. 1. Laboratory evaluations

Strek

1998

Pestic. Sci.

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“…It can be explained by the cleavage of the two N±C ureic bonds, which is the typical degradation pathway of sulfonylurea herbicides. The three compounds (3, 4 and 5) also represent the most important metabolites of chlorsulfuron and metsulfuron-methyl in the environment 3,8,9 Previous work has identi®ed 6 as a photoproduct of 1 in water. 3 In this study, the product 6 was probably formed by oxidation of 4 in analogy to the photochemical generation of the nitrosoproduct from N-(4-chlorophenyl)benzenesulfonamide 10 We have noticed that the alcoholysis of chlorsulfuron did not yield saccharin (7) according to Sabadie,11 though saccharin was often reported as a hydrolysis product or metabolite of some sulfonylurea herbicides.…”

Section: Discussionmentioning

confidence: 99%

Photolysis of chlorsulfuron and metsulfuron-methyl in methanol

et al. 1999

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Photolysis of chlorsulfuron and metsulfuron-methyl was studied in methanol under UV light. Their rates of primary photolysis followed ®rst-order kinetics. The main photoproducts were identi®ed as 2-methoxy-4-methyl-1,3,5-triazin-6-amine, 2-chloro-benzenesulfonamide and methyl 2-(aminosulfonyl)benzoate, which entailed the cleavage of the two N±C ureic bonds. Further photolysis of benzenesulfonamide derivatives involved oxidation of ÀNH 2 , cyclisation with loss of CH 3 OH, and scission of the C±S bond A trace of methyl o-mercaptobenzoate was also detected. The corresponding photolysis pathways of chlorsulfuron and metsulfuron-methyl were tentatively proposed.

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“…It was tentatively identified as methyl 2-[[[[[amino(imino)methyl]amino]carbonyl]amino]sulfonyl]benzoate. A compound analogous to 10 was identified in poultry metabolites of bensulfuron-methyl [13].…”

Section: Hydrolysis Metabolitesmentioning

confidence: 99%

“…A low-temperature mass spectral ionization technique, such as fast-atom bombardment (FAB) or electrospray ionization (ESI), is needed to obtain prominent molecular ions for unequivocal molecular-weight assignments. Reiser et al have shown LC/FAB-MS to be a very powerful analytical method for the identification of unknown sulfonylurea herbicide metabolites [13].…”

Section: Introductionmentioning

confidence: 99%