Screening triclocarban and its transformation products in river sediment using liquid chromatography and high resolution mass spectrometry.

An analytical method was developed and validated for the target screening of triclosan (TCS), triclocarban (TCC) and its lesser and higher chlorinated congeners namely, 4,4'-dichlorocarbanilide (DCC) 3,3',4,4'-tetrachlorocarbanilide (3-Cl-TCC) and 2,3',4,4'-tetrachlorocarbanilide (2-Cl-TCC) in river sediment. Sediment samples were extracted by pressurized liquid extraction and quantification and identification of target compounds were carried by liquid chromatography high resolution mass spectrometry (LC-HRMS). The overall method recoveries were 89% with relative standard deviations below 6%. Method detection limits ranged from 0.01 to 0.12 ng/g. The usefulness of the method was demonstrated on sediment samples collected downstream of three wastewater treatment plants in an attempt to provide with a set of occurrence data of these biocides in France and for a better understanding of their fate in river. Major results are the following: TCC, DCC and 3-Cl-TCC were ubiquitously detected demonstrating that these emerging contaminants have been probably overlooked in France. Reductive dechlorination of TCC into DCC was also ubiquitous but predominated in anoxic sediment. 3-Cl-TCC is probably more persistent than TCC and LC-HRMS enabled the detection and identification of a suite of other chlorinated biocides in river sediment.

Presence of illicit drugs and metabolites in influents and effluents of 25 sewage water treatment plants and map of drug consumption in France.

Consumption of illicit drugs is a new concern for water management that must be considered not only because of the social and public health aspects but also in an environmental context in relation with the contamination of surface waters. Indeed, sewage treatment plant (STP) effluents contain drug residues that have not been eliminated since STP treatments are not completely efficient in their removal. We developed and validated an HPLC-MS/MS analytical method to assess the concentrations of 17 illicit drugs and metabolites in raw urban wastewaters: cocaine and its metabolites, amphetamine and amphetamine-likes (methamphetamine, MDMA, MDEA, MDA), opiates and opiate substitutes (methadone and buprenorphine), and THC-COOH cannabis metabolite. This method has been applied to the analysis of influent and effluent samples from 25 STPs located in France all over the country. The results allowed evaluating the drug consumption in the areas connected to the STPs and the efficiency of the treatment technology implied. We selected STPs according to their volume capacity, their treatment technologies (biofilters, activated sludges, MBR) and their geographical location. In influents, the concentrations varied between 6 ng/L for EDDP (main metabolite of methadone) and 3050 ng/L for benzoylecgonine (cocaine metabolite). Consumption maps were drawn for cocaine, MDMA, opiates, cannabis and amphetamine-like compounds. Geographical significant differences were observed and highlighted the fact that drug consumption inside a country is not homogeneous. In parallel, comparisons between STP technology processes showed differences of efficiency. More, some compounds appear very resistant to STP processes leading to the contamination of receiving water.

GC-MS(n) and LC-MS/MS couplings for the identification of degradation products resulting from the ozonation treatment of Acetochlor.

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 MS(n) 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.

Investigation of the dissociation pathways of metolachlor, acetochlor and alachlor under electron ionization - application to the identification of ozonation products.

With the future aim of using gas chromatography coupled with mass spectrometry to characterize the transformation products of ozonated herbicides: metolachlor, acetochlor and alachlor, an interpretation of their electron ionization mass spectra is presented. Fragmentation mechanisms are proposed on the basis of isotopic labelling and multiple-stage mass spectrometry experiments carried out on an ion trap mass spectrometer. We also give examples in order to demonstrate how the elucidation of such fragmentation mechanisms for herbicides may simplify the characterization of their ozonation products.