Photolytic degradation of fluoroquinolone carboxylic acids in aqueous solution .2. Isolation and structural elucidation of polar photometabolites

Subsequent to irradiation with a xenon lamp simulating sunlight, fluoroquinolone carboxylic acids in aqueous solution form polar pyridone dicarboxylic and tricarboxylic acids. After liquid/liquid partition with chloroform/water these substances can be isolated by ion exchange chromatography of the aqueous phase. They can be regarded as intermediate compounds on the route to a complete photomineralization. The structural elucidation is performed by such mass spectroscopic methods as MS, GC/MS and HPLC/MS, whereby HPLC/MS shows the highest reliability. Additionally H-1- and C-13-NMR measurements confirm the structure of the main polar degradation product.