GC‐MSⁿ and LC‐MS/MS couplings for the identification of degradation products resulting from the ozonation treatment of Acetochlor

Abstract

The degradation of the chloracetamide herbicide acetochlor has been studied under simulated ozonation treatment plant conditions. The degradation of acetochlor included the formation of several degradation products that were identified using GC/ion‐trap mass spectrometry with EI and CI and HPLC/electrospray‐QqTOF mass spectrometry. Thirteen ozonation products of acetochlor have been identified. Ozonation of the deuterated herbicide combined to MSn and high‐resolution mass measurement allowed effective characterization of the degradation products. At the exception of one of them, the product B (2‐chloro‐2', ethyl‐6', methyl‐acetanilide), none of the identified degradation products has been already reported in the literature. Post‐ozonation kinetics studies revealed that the concentrations of most degradation products evolved noticeably with time, particularly during the first hours following the ozonation treatment. This raises concerns about the fate of degradation products in the effluents of treatment plants and suggests the need for a better control on these products if their toxicity was demonstrated. Copyright © 2012 John Wiley & Sons, Ltd.

Photolysis and photocatalysis of ibuprofen in aqueous medium: characterization of by‐products via liquid chromatography coupled to high‐resolution mass spectrometry and assessment of their toxicities against Artemia Salina

“…6(d)). This result suggests that UV-A radiation is not energetic enough to excite 1 and thus to cause its conversion into the subsequent intermediates (2)(3)(4)(5)(6)(7)(8)(9)(10)(11), as observed for the other systems (TiO 2 / UV-C, TiO 2 /UV-A and UV-C) evaluated herein.…”

“…It is important to mention that some of these intermediates (1, 2, 6, 8 and 9) have been previously reported by several research groups. [25,32,36,38,45,51,53,54] The evolution of each intermediate (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11) formed during the photodegradation processes could then be monitored by LC-HRMS. The results from the extracted-ion chromatograms ( Fig.…”

“…To improve the efficiency of removal of pharmaceutical compounds in aqueous media, novel and powerful technologies have been developed, especially the so‐called advanced oxidation processes (AOPs). Moreover, there has been a growing interest in the detection and identification of degradation products resulting from the application of AOPs . Among the AOPs, the following processes are noteworthy: photolysis, photocatalysis, electrochemistry and photoelectrochemistry .…”

“…Moreover, there has been a growing interest in the detection and identification of degradation products resulting from the application of AOPs. [9,10] Among the AOPs, the following processes are noteworthy: photolysis, [11][12][13][14][15][16] photocatalysis, [17] electrochemistry and photoelectrochemistry. [18,19] However, many challenging issues still remain, which are mainly related to the fact that products arising from the degradation of pollutants may present higher toxicity than their predecessors.…”

Photodegradation of dimethenamid-P in deionised and ground water

“…From the analysis of the obtained peaks identified by the value of m/z ratios, based on the molecular weight and the nature of the chemical bond in the molecule of DMA-P, the occurrence of transformation products can be confirmed, which is illustrated in Figure 7. The efficiency of LC-MS hyphenated techniques for the characterization of various photodegradation [30,31] products has been recently reported for chloracetamide herbicide acetochlor, which has similar structure as the investigated dimethenamide-P. HPLC/MS analysis of the reaction mixture after 10 minutes of the photocatalytic degradation, revealed the presence of one degradation product with m/z of 110.5. From the structural analysis of DMA-P it can be assumed that the cleavage of C-N bond occurred (path I) and that the dimethylthiophenyl cation has been formed, as shown in Figure 7.…”