Trace residue analysis of the herbicide chlorsulfuron in soil by gas chromatography-electron capture detection

Ahmad, Ijaz; Crawford, George

doi:10.1021/jf00091a029

Cited by 41 publications

(25 citation statements)

References 5 publications

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“…After derivatization with diazomethane (in diethyl ether solution), the final residue was reconstituted in 1.0 ml of hexane, and an aliquot was subjected to achiral HPLC analysis. Diazomethane was prepared as described in the literature and stored in diethyl ether at −20 °C . The extraction procedure gave recoveries of >80% with <8% relative standard deviations at 1.0 and 0.1 µg/g spike levels ( n = 3) for quizalofop‐ethyl and quizalofop‐acid.…”

Section: Methodsmentioning

confidence: 99%

Enantioselectivity in degradation and transformation of quizalofop‐ethyl in soils

Cheng

et al. 2012

Chirality

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The enantioselective degradation of quizalofop-ethyl and its metabolite quizalofop-acid in two soils, a Wuhan acidic soil and a Baoding alkaline soil, was investigated. The dissipation of quizalofop-ethyl consisted of two phases, a rapidly deceasing first phase that lasted 1 day and a slowly decreasing second phase that extended till the end of the incubation. It is shown that S-quizalofop-ethyl degraded slightly faster than R-quizalofop-ethyl in the two soils. Further incubation of enantiopure enaniomers showed that quizalofop-ethyl was configurationally stable in soil. Quizalofop-acid was produced quickly, and its amount reached a maximum at 1-6 days time and then decreased slowly with half-lives ranging from 11 to 21 days. The results also showed that quizalofop-acid degraded faster in the acidic Wuhan soil than in the alkaline Baoding soil. At last, significant enantiomerization from S-quizalofop-acid to R-quizalofop-acid was observed, and the enantiomerization was fast, resulting in residues enriched with R-quizalofop-acid whatever racemic quizalofop-ethyl or pure enantiomers were initially applied in the soils.

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Section: Methodsmentioning

confidence: 99%

Enantioselectivity in degradation and transformation of quizalofop‐ethyl in soils

Cheng

et al. 2012

Chirality

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“…Sulfonylurea herbicides are generally not directly amenable to separation by gas chromatography (GC) because of their low volatility and thermal instability. GC applications are thus limited to detection of the esters employing, for example, diazomethane derivatization (Ahmad & Crawford, 1990;Klaffenbach, Holland, & Lauren, 1993) and pentafluorobenzyl bromide derivatization (Cotterill, 1992). Liquid chromatography combined with mass spectrometry (LC-MS) is thus the technique of choice for the analysis of sulfonylurea herbicides (Di Corcia et al, 1997;Krynitsky, 1997;Furlong et al, 2000).…”

Section: Mass Spectrometrymentioning

confidence: 99%

Mass spectrometry of the photolysis of sulfonylurea herbicides in prairie waters

Headley

Peru

et al. 2009

Mass Spectrometry Reviews

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This review of mass spectrometry of sulfonylurea herbicides includes a focus on studies relevant to Canadian Prairie waters. Emphasis is given to data gaps in the literature for the rates of photolysis of selected sulfonylurea herbicides in different water matrices. Specifically, results are evaluated for positive ion electrospray tandem mass spectrometry with liquid chromatography separation for the study of the photolysis of chlorsulfuron, tribenuron-methyl, thifensulfuron-methyl, metsulfuron-methyl, and ethametsulfuron-methyl. LC-MS/MS is shown to be the method of choice for the quantification of sulfonylurea herbicides with instrumental detection limits ranging from 1.3 to 7.2 pg (on-column). Tandem mass spectrometry coupled with the use of authentic standards likewise has proven to be well suited for the identification of transformation products. To date, however, the power of time-of-flight MS and ultrahigh resolution MS has not been exploited fully for the identification of unknown photolysis products. Dissipation of the herbicides under natural sunlight fit pseudo-first-order kinetics with half-life values ranging from 4.4 to 99 days. For simulated sunlight, radiation wavelengths shorter than 400 nm are required to induce significant photolytic reactions. The correlation between field dissipation studies and laboratory photolysis experiments suggests that photolysis is a major pathway for the dissipation of some sulfonylurea herbicides in natural Prairie waters.

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“…The mass spectrum of first minor product (2) showed molecular ion peak at m/z 173 (M + ) with fragment ion peaks at m/z 158 (M + -15) due to loss of methyl from the parent molecule at m/z 138 (M + -35) due to loss of chlorine atom from the parent molecule ( Figure 1). On the basis of mass spectrum it was tentatively identified as 4-chloro-6-methoxy-2-N-methylamino pyrimidine (2).…”

Section: Resultsmentioning

confidence: 99%

Reaction of chlorimuron‐ethyl with diazomethane

Choudhury

Dureja

1996

Toxicological & Environmental Chemistry

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Methylation of chlorimuron-ethyl with etheral solution of diazomethane gave ethyl-2-[[[[(4-chloro-6-methoxy-2-pyrimidinyl) N-methylamino] carbonyl] N-methylamino] sulfonyl] benzoate (dimethyl derivative of chlorimuron-ethyl) as the major product along with 4-chloro-6-methoxy-2-N-methylamino pyrimidine, 2-aminomethyl sulfonyl benzoic acid, ethyl-2-[(N-methylamino) sulfonyl] benzoate, ethyl-2-[N,N-dimethylamino) sulfonyl] benzoate and o-benzoic sulf-N-methylimide as the minor products.

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Trace residue analysis of the herbicide chlorsulfuron in soil by gas chromatography-electron capture detection

Cited by 41 publications

References 5 publications

Enantioselectivity in degradation and transformation of quizalofop‐ethyl in soils

Enantioselectivity in degradation and transformation of quizalofop‐ethyl in soils

Mass spectrometry of the photolysis of sulfonylurea herbicides in prairie waters

Reaction of chlorimuron‐ethyl with diazomethane

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