The aqueous photolysis of four pharmaceuticals with varying fluorinated functional groups was assessed under neutral, alkaline, advanced oxidation, and advanced reduction conditions with varying light sources. Solar simulator quantum yields were 2.21 × 10−1 mol Ei−1for enrofloxacin, 9.36 × 10−3 mol Ei−1for voriconazole, and 1.49 × 10−2 mol Ei−1for flecainide. Florfenicol direct photolysis was slow, taking 150 h for three degradation half‐lives. Bimolecular rate constants between pharmaceuticals and hydroxyl radicals were 109to 1010 M−1 s−1. Using a combined quantitative fluorine nuclear magnetic resonance spectroscopy (19F‐NMR) and mass spectrometry approach, fluorine mass balances and photolysis product structures were elucidated. Enrofloxacin formed a variety of short‐lived fluorinated intermediates that retained the aryl F motif. Extended photolysis time led to complete aryl F mineralization to fluoride. The aliphatic F moiety on florfenicol was also mineralized to fluoride, but the resulting product was a known antibiotic (thiamphenicol). For voriconazole, the two aryl Fs contributed more to fluoride production compared with the heteroaromatic F, indicating higher stability of the heteroaromatic F motif. The two aliphatic CF3moieties in the flecainide structure remained intact under all conditions, further supporting the stability of these moieties found in per‐ and polyfluoroalkyl substances under a variety of conditions. The advanced treatment conditions generating hydroxyl radicals or hydrated electrons accelerated the degradation, but not the defluorination, of flecainide. The combination of19F‐NMR and mass spectrometry proved powerful in allowing identification of fluorinated products and verifying the functional groups present in the intermediates and products. The results found in the present study will aid in the understanding of which fluorinated functional groups should be incorporated into pharmaceuticals to ensure organofluorine byproducts are not formed in the environment and help determine the water‐treatment processes that effectively remove specific pharmaceuticals and more generally fluorinated motifs.
Fluoride is an environmental toxin prevalent in water, soil, and air. A fluoride transporter called Fluoride EXporter (FEX) has been discovered across all domains of life, including bacteria, single cell eukaryotes, and all plants, that is required for fluoride tolerance. How FEX functions to protect multicellular plants is unknown. In order to distinguish between different models, the dynamic movement of fluoride in wildtype (WT) and
- NSF-PAR ID:
- 10490349
- Publisher / Repository:
- Springer Science + Business Media
- Date Published:
- Journal Name:
- Plant Molecular Biology
- Volume:
- 114
- Issue:
- 1
- ISSN:
- 0167-4412
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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