Behavior of amoxicillin in wastewater and river water: identification of its main transformation products by liquid chromatography/electrospray quadrupole time‐of‐flight mass spectrometry

Abstract

The identification of transformation products (TPs) of pharmaceuticals in the environment is essentially a challenging task due to the lack of standards and the instrumental capabilities required to detect compounds (sometimes unknowns) that are produced under environmental conditions. In this work, we report the use of liquid chromatography/electrospray quadrupole time-of-flight mass spectrometry (LC/QTOF-MS/MS) as a tool for the identification of amoxicillin (AMX) and its main TPs in wastewater and river water samples. Laboratory degradation experiments of AMX were performed in both alkaline and acidic media in order to confirm that the expected transformation pathway in the aquatic media is through the β-lactam ring cleavage. A thorough study was carried out with both standards and real samples (wastewater and river water samples). Four compounds were identified as main TPs: both amoxicillin diketopiperacine-2',5' and amoxilloic acid diastereomers. Amoxilloic acid stereoisomers are reported for the first time in environmental matrices. The transformation product (5R)-amoxicillin diketopiperacine-2',5' was frequently detected in river waters. Besides, another AMX transformation product formed during analysis was also structurally elucidated for the first time (amoxicilloic acid methyl ester) via accurate mass measurements. Collected data show that although AMX is not present as such in environmental samples, different TPs occur. This study represent a valuable indicator of the potential of LC/QTOF-MS/MS for the identification and structural elucidation of TPs in the environment using accurate MS/MS experiments, enabling thus the recognition of the environmental transformation pathway.

Targeted and non-targeted liquid chromatography-mass spectrometric workflows for identification of transformation products of emerging pollutants in the aquatic environment

“…Due to the increasing occurrence of EPs in wastewaters, the formation of TPs during biological treatment and the mechanisms involved have been investigated for various classes of compounds {i.e., antibiotics [35,45,54], analgesics (painkillers) [39], anticonvulsants [37], anti-inflammatories [40,41], iodinated X-ray contrast media (ICM) [46,47] and anti-viral/-bacterial/-fungal agents [33,56,57]}. Most of the studies were performed in batch systems with activated sludge.…”

“…There are few studies with direct injection of environmental samples for the identification of TPs. More often, sediments, activated sludge, wastewater and river-water samples were collected and subjected to solid-phase extraction (SPE) or liquidliquid extraction (LLE) prior to analysis, for enrichment of the analytes [35,44,51]. To achieve sufficient enrichment for a broad range of compounds, including TPs with different physical-chemical properties, Kern et al used simultaneously four different SPE sorbents in one HPLC-UV, UPLC-Q-ToF-MS/MS Waters MassLynx, mass accuracy, fragmentation pattern [75] cartridge (weak anion, weak cation-exchange material, and nonpolar and hydrophilic-lipophilic interaction sorbents) [5].…”

Development and Validation of a Fast Procedure To Analyze Amoxicillin in River Waters by Direct-Injection LC–MS/MS

“…[1][2][3] When ingested, 80 to 90% of this antibiotic is excreted unmodified 4 via urine and faeces into the domestic sewage and subsequently discharged to wastewater treatment plants (WWTPs). [4][5][6] Because most WWTPs are not designed to remove antibiotics, amoxicillin is released into the environment.…”

“…[1][2][3] When ingested, 80 to 90% of this antibiotic is excreted unmodified 4 via urine and faeces into the domestic sewage and subsequently discharged to wastewater treatment plants (WWTPs). [4][5][6] Because most WWTPs are not designed to remove antibiotics, amoxicillin is released into the environment. [7][8][9] This situation became an emerging issue because the antibiotics can act as persistent and bioaccumulative contaminants, inducing toxic effects in aquatic or terrestrial ecosystems, even in low concentrations levels (in the range of µg-ng.L -1 ).…”

Advanced analytical tools for the investigation of licit and illicit drug residues in water

“…Pérez-Parada et al [91] performed solely hydrolysis degradation experiments on amoxicillin in both alkaline and acidic aqueous media. Four compounds were identified as main TPs by LC-QTOF-MS. Data showed that although this antibiotic is not present as such in environmental samples, different TPs might occur.…”