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

- LC-HRMS method was validated to quantify TCC and transformation products in sediment
- TCC, DCC and 3-Cl-TCC were ubiquitously detected in the 1-500 ng/g range
- DCC/TCC ratio increase highlighted reductive dechlorination in anoxic sediment
- 3-Cl-TCC is probably more persistent than TCC
- Other suspected chlorinated biocides were also detected in sediment

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.