Health & Environmental Research Online (HERO)


Print Feedback Export to File
3173284 
Journal Article 
New hydrolysis products of the beta-lactam antibiotic amoxicillin, their pH-dependent formation and search in municipal wastewater 
Hirte, K; Seiwert, B; Schüürmann, G; Reemtsma, T 
2016 
1 
Water Research
ISSN: 0043-1354
EISSN: 1879-2448 
88 
880-888 
English 
26613181 
Amoxicillin (AMX) is a widespread β-lactam-antibiotic and, together with some of its transformation products (TPs) originating from hydrolysis, a known environmental contaminant. To shed light on the abiotic degradation of AMX and the stability of its known TPs, laboratory hydrolysis experiments of AMX were carried out at pH 3, 7 and 11. Not only the rate of hydrolysis but also the pattern of TPs was strongly pH-dependent. The time courses of the obtained transformation products were analyzed by UPLC-HR-QToF-MS. AMX penicilloic acid (TP 1), AMX 2',5'-diketopiperazine (TP 2), AMX penilloic acid (TP 3) and 3-(4-hydroxyphenyl)pyrazinol (TP 4) were found at neutral pH. Surprisingly, the first three were not stable but transformed into 23 yet unknown TPs within three to four weeks. Seven TPs were tentatively identified, based on their product ion spectra and, where possible, confirmed with reference standards, e.g. penicillamine disulfide, 2-[amino(carboxy)methyl]-5,5-dimethyl-1,3-thiazolidine-4-carboxylic acid and dehydrocarboxylated amoxicillin penilloic acid. Analysis of samples from municipal wastewater treatment plants confirmed these findings with TP 1 being the dominant TP in the influent and a shift towards TP 2, TP 3 and TP 4 in the effluents. The lab experiments predicted up to 13 consecutive TPs from TP 1, TP 2 and TP 3 under neutral conditions. Their detection from surface waters will be difficult, because their large number and slow formation kinetics will lead to comparatively low environmental concentrations. Nevertheless the abiotic degradation of TP 1, TP 2 and TP 3 to further TPs needs to be considered in future studies of the environmental fate of amoxicillin.