Kinetic study on acid-base catalyzed hydrolysis of azimsulfuron, a sulfonylurea herbicide

Khan, M. Niyaz; Bakar, Baki Bin; Yin, Fenny W. N.

doi:10.1002/(sici)1097-4601(1999)31:4<253::aid-kin2>3.0.co;2-x

Cited by 9 publications

(7 citation statements)

References 27 publications

(28 reference statements)

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“…To check a possible matrix effect, the study was also performed for solution 5.00 mg L Ϫ1 of tribenuron methyl in paddy water that underwent solar box irradiation for times 5,13,15,18, and 20 days. Also, in paddy water solution the degradation process is firstorder reaction with a value of t 1/2 of 120 h (kinetic constant ϭ 0.006 h Ϫ1 ), much greater than that obtained in ultrapure water solution (t 1/2 ϭ 6.80 h) that underwent irradiation but lower with respect to dark control.…”

Section: Hplc-dad-ms/ms Analysis Of Tribenuron Methyl Solutions In Pamentioning

confidence: 99%

Hydrolytic and photoinduced degradation of tribenuron methyl studied by HPLC-DAD-MS/MS

Bottaro

Frascarolo

Gosetti

et al. 2008

J. Am. Soc. Mass Spectrom.

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The©paper©studies,©with©the©help©of©HPLC-DAD-MS/MS©technique,©the©hydrolytic©and photoinduced©degradation©processes©that©take©place©in©aqueous©solutions©of©tribenuron methyl,© both© when© preserved© in© the© dark© and© when© undergoing© solar© box© irradiation© under conditions© that© simulate© sun© light.© The© results© indicate© that© the© degradation© products© formed by© hydrolysis© alone© and© by© photoirradiation© are© the© same,© but© kinetics© of© the© hydrolysis reaction©is©much©slower.©The©degradation©products©are©identified©as©2-methoxy-4-methylamino-6-methyl-1,3,5-triazine© (P1),© methyl© 2-aminosulfonylbenzoate© (P2),© and© saccharin© (P3)© and© quantified.© Ecotoxicological© biotests© performed© on© 0.1© g L Ϫ1 photoirradiated solutions of the herbicide give a border line toxicity situation comparable to that of the precursor and indicate that the herbicide is characterized by low persistence in the environment, as required. Its degradation, however, does not lead to mineralization but to the formation of products of comparable toxicity. To evaluate the matrix effects, the photodegradation of the herbicide is also studied in the presence of rice paddy waters: the process is slower than in ultrapure water but leads to the same products. Experiments performed for comparison by irradiating ultrapure water solutions with UV lamp (254 nm) show that the degradation process is not only faster with respect to sunlight, but gives a different pathway, without in anyway leading to mineralization. T he more recent herbicide formulations are designed to offer advantages of the highest selectivity together with the lowest persistence in the environment: sulfonylurea herbicides meet these requirements. But, unfortunately, lower persistence in the environment does not necessarily correspond to lower toxicity, since many herbicides undergo natural degradation reactions in the environment that do not lead to mineralization but to the formation of new species potentially more toxic and stable than the precursors [1][2][3][4][5]. The evaluation of the degradation pathway and the structures and toxicity of the degradation products is therefore of paramount importance.The natural degradation of sulfonylurea herbicides takes place through aqueous hydrolysis reactions [6 -8], microbial processes (mainly occurring in soils) [9 -11], or photodegradation reactions [1-3, 5, 12-14]. These processes in surface waters and in soil are concomitant [7,15,16].HPLC-DAD-MS/MS methods are employed here to investigate and compare the hydrolytic and photoinduced degradation pathways of aqueous solutions of tribenuron methyl (methyl [2-4-methoxy-6-methyl-1,3,5-triazin-2-yl(methyl)carbamoyl sulfamoyl]benzoate) (Scheme 1), largely used against broad-leaved weeds in crops of cereals and in particular of rice.TiO 2 assisted photodegradation often leads to complete mineralization and can be used to dissipate pollutants in remediation strategy [17][18][19][20]. We are interested here to study the natural photodegradation of tribenuron methyl in...

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Section: Hplc-dad-ms/ms Analysis Of Tribenuron Methyl Solutions In Pamentioning

confidence: 99%

Hydrolytic and photoinduced degradation of tribenuron methyl studied by HPLC-DAD-MS/MS

Bottaro

Frascarolo

Gosetti

et al. 2008

J. Am. Soc. Mass Spectrom.

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“…Nicosulfuron, a member of the sulfonylurea herbicides used to control broad-leaved weeds and sedge weeds in corn, rice, citrus, vines, and potatoes field, was introduced into China and became the utmost frequently used herbicide on account of its high herbicidal activity at low application rates 1 . The persistence of nicosulfuron in dugout water was longer than sulfosulfuron and rimsulfuron 2 .…”

Section: Introductionmentioning

confidence: 99%

Hydrolysis of nicosulfuron under acidic environment caused by oxalate secretion of a novel Penicillium oxalicum strain YC-WM1

Feng

Zheng

Song

et al. 2017

Sci Rep

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A novel Penicillium oxalicum strain YC-WM1, isolated from activated sludge, was found to be capable of completely degrading 100 mg/L of nicosulfuron within six days when incubated in GSM at 33 °C. Nicosulfuron degradation rates were affected by GSM initial pH, nicosulfuron initial concentration, glucose initial concentration, and carbon source. After inoculation, the medium pH was decreased from 7.0 to 4.5 within one day and remained at around 3.5 during the next few days, in which nicosulfuron degraded quickly. Besides, 100 mg/L of nicosulfuron were completely degraded in GSM medium at pH of 3.5 without incubation after 4 days. So, nicosulfuron degradation by YC-WM1 may be acidolysis. Based on HPLC analysis, GSM medium acidification was due to oxalate accumulation instead of lactic acid and oxalate, which was influenced by different carbon sources and had no relationship to nicosulfuron initial concentration. Furthermore, nicosulfuron broke into aminopyrimidine and pyridylsulfonamide as final products and could not be used as nitrogen source and mycelium didn’t increase in GSM medium. Metabolomics results further showed that nicosulfuron degradation was not detected in intracellular. Therefore, oxalate secretion in GSM medium by strain YC-WM1 led to nicosulfuron acidolysis.

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“…1996). As for the most sulfonylureas, azimsulfuron hydrolytic degradation involves the cleavage of the sulfonylurea bridge, leading to the formation of a substituted pyrimidine and the corresponding sulfonamide (Khan et al. 1999).…”

Section: Introductionmentioning

confidence: 99%

“…In soil and water, indirect photolysis and microbial activity are considered the most important azimsulfuron degradation mechanisms (Barefoot et al 1996). As for the most sulfonylureas, azimsulfuron hydrolytic degradation involves the cleavage of the sulfonylurea bridge, leading to the formation of a substituted pyrimidine and the corresponding sulfonamide (Khan et al 1999). The highest levels of sorption have been observed in soil at low pH values and with high organic carbon and/or clay content .…”

Section: Introductionmentioning

confidence: 99%

The microbial degradation of azimsulfuron and its effect on the soil bacterial community

et al. 2006

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Aims: Azimsulfuron is a recently introduced sulfonylurea herbicide useful in controlling weeds in paddy fields. To date very little information is available on the biodegradation of this pesticide and on its effect on the soil microbial community. The aim of this work was to study its biodegradation both in slurry soil microcosms and in batch tests with mixed and pure cultures. Methods and Results: Azimsulfuron was applied to forest bulk soil in order to study its effect on the structure of the bacterial soil community, as detectable by denaturant gradient gel electrophoresis (DGGE) analyses. Biodegradation and abiotic processes were investigated by HPLC analyses. In addition, a microbial consortium was selected, that was able to use azimsulfuron as the sole energy and carbon source. One of the metabolites produced by the consortium was isolated and identified through LC‐MS analyses. Cultivable bacteria of the consortium were isolated and identified by 16S rDNA sequencing (1400 bp). Conclusions: Azimsulfuron treatment seems to have the ability to cause changes in the bacterial community structure that are detectable by DGGE analyses. It is easily biodegraded both in microcosms and in batch tests, with the formation of an intermediate that was identified as 2‐methyl‐4‐(2‐methyl‐2H‐tetrazol‐5‐yl)‐2H‐pyrazole‐3‐sulfonamide. Significance and Impact of the Study: The study increases the knowledge on the biodegradation of azimsulfuron and its effects on the soil microbiota.

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Kinetic study on acid-base catalyzed hydrolysis of azimsulfuron, a sulfonylurea herbicide

Cited by 9 publications

References 27 publications

Hydrolytic and photoinduced degradation of tribenuron methyl studied by HPLC-DAD-MS/MS

Hydrolytic and photoinduced degradation of tribenuron methyl studied by HPLC-DAD-MS/MS

Hydrolysis of nicosulfuron under acidic environment caused by oxalate secretion of a novel Penicillium oxalicum strain YC-WM1

The microbial degradation of azimsulfuron and its effect on the soil bacterial community

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