2 research outputs found
Origin of Xylitol in Chewing Gum: A Compound-Specific Isotope Technique for the Differentiation of Corn- and Wood-Based Xylitol by LC-IRMS
The sugar replacement compound xylitol
has gained increasing attention
because of its use in many commercial food products, dental-hygiene
articles, and pharmaceuticals. It can be classified by the origin
of the raw material used for its production. The traditional ābirch
xylitolā is considered a premium product, in contrast to xylitol
produced from agriculture byproducts such as corn husks or sugar-cane
straw. Bulk stable-isotope analysis (BSIA) and compound-specific stable-isotope
analysis (CSIA) by liquid-chromatography isotope-ratio mass spectrometry
(LC-IRMS) of chewing-gum extracts were used to determine the Ī“<sup>13</sup>C isotope signatures for xylitol. These were applied to elucidate
the original plant type the xylitol was produced from on the basis
of differences in isotope-fractionation processes of photosynthetic
CO<sub>2</sub> fixation. For the LC-IRMS analysis, an organic-solvent-free
extraction protocol and HPLC method for the separation of xylitol
from different artificial sweeteners and sugar-replacement compounds
was successfully developed and applied to the analysis of 21 samples
of chewing gum, from which 18 could be clearly related to the raw-material
plant class
Direct Photolysis of Sulfamethoxazole Using Various Irradiation Sources and Wavelength RangesīøInsights 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 (Īµ<sub>C</sub> = ā4.8 Ā± 0.1 ā°).
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