LC/MS/MS and LC/NMR for the Structure Elucidation of Ciprofloxacin Transformation Products in Pond Water Solution

摘要

LC/MS/MS and LC/NMR have been utilized to investigate the transformation of the fluoroquinolone antibiotic, ciprofloxacin, in a natural water sample. Antibiotics, such as fluoroquinolones, are often prescribed in relatively high doses of which only a percentage of the active drug is actually effectively metabolized. The unmetabolized drug has the potential to make its way into the environment where it can have a major impact on the natural microbial community. Although the human metabolites of these pharmaceuticals are well characterized, the identification and structure elucidation of metabolites formed in the environment presents a significant analytical challenge. LC/MS/MS and LC/NMR methods have been developed for the separation and structure elucidation of ciprofloxacin and its transformation products. Two predominant transformation products were identified using NMR to obtain chemical shift, coupling and integration information. Tandem mass spectrometry was exploited to confirm the structure elucidated by NMR through the fragmentation patterns and neutral losses observed. The transformation products identified included (1) the substitution of the fluorine on the fluoroquinolone ring with a hydroxyl group and (2) the loss of ethylene by cleavage of the piperazine ring.