1 research outputs found
Direct Photolysis of Sulfamethoxazole Using Various Irradiation Sources and Wavelength Rangesî—¸Insights from Degradation Product Analysis and Compound-Specific Stable Isotope Analysis
The
environmental micropollutant sulfamethoxazole (SMX) is susceptible
to phototransformation by sunlight and UV-C light which is used for
water disinfection. Depending on the environmental pH conditions SMX
may be present as neutral or anionic species. This study systematically
investigates the phototransformation of these two relevant SMX species
using four different irradiation scenarios, i.e., a low, medium, and
high pressure Hg lamp and simulated sunlight. The observed phototransformation
kinetics are complemented by data from compound-specific stable isotope
and transformation product analysis using isotope-ratio and high-resolution
mass spectrometry (HRMS). Observed phototransformation kinetics were
faster for the neutral than for the anionic SMX species (from 3.4
(LP lamp) up to 6.6 (HP lamp) times). Furthermore, four phototransformation
products (with <i>m</i>/<i>z</i> 189, 202, 242, and 260) were detected by HRMS that have not yet
been described for direct photolysis of SMX. Isotopic fractionation
occurred only if UV-B and UV-A wavelengths prevailed in the emitted
irradiation and was most pronounced for the neutral species with simulated
sunlight (ε<sub>C</sub> = −4.8 ± 0.1 ‰).
Phototransformation of SMX with UV-C light did not cause significant
isotopic fractionation. Consequently, it was possible to differentiate
sunlight and UV-C light induced phototransformation of SMX. Thus,
CSIA might be implemented to trace back wastewater point sources or
to assess natural attenuation of SMX by sunlight photolysis. In contrast
to the wavelength range, pH-dependent speciation of SMX hardly impacted
isotopic fractionation