Background Food contact materials (FCM) may contain non-intentionally added substances (NIAS) as a result of reaction by-products, oligomers, degradation processes, chemical reactions between packaging materials and foodstuff, or as impurities from the raw materials used for their production.
A gas permeable liquid core waveguide (LCW) was successfully used for the simulation and in situ spectroscopic analysis of the photodegradation processes of the two dyes crystal violet and eosin Y.
In many areas, studying
photostability or the mechanism of photodegradation
is of high importance. Conventional methods to do so can be rather
time-consuming, laborious, and prone to experimental errors. In this
paper we evaluate an integrated and fully automated system for the
study of light-induced degradation, comprising a liquid handler, an
irradiation source and exposure cell with dedicated optics and spectrograph,
and a liquid chromatography (LC) system. A liquid core waveguide (LCW)
was used as an exposure cell, allowing efficient illumination of the
sample over a 12 cm path length. This cell was coupled to a spectrograph,
allowing in situ absorbance monitoring of the exposed sample during
irradiation. The LCW is gas-permeable, permitting diffusion of air
into the cell during light exposure. This unit was coupled online
to LC with diode array detection for immediate and automated analysis
of the composition of the light-exposed samples. The analytical performance
of the new system was established by assessing linearity, limit of
detection, and repeatability of the in-cell detection, sample recovery
and carryover, and overall repeatability of light-induced degradation
monitoring, using riboflavin as the test compound. The applicability
of the system was demonstrated by recording a photodegradation time
profile of riboflavin.
Photodegradation greatly affects everyday life. It poses
challenges
when food deteriorates or when objects of cultural heritage fade,
but it can also create opportunities applied in advanced oxidation
processes in water purification. Studying photodegradation, however,
can be difficult because of the time needed for degradation, the inaccessibility
of pure compounds, and the need to handle samples manually. A novel
light-exposure cell, based on liquid-core-waveguide (LCW) technology,
was embedded in a multiple-heart-cut two-dimensional liquid chromatography
system by coupling the LCW cell to the multiple-heart-cut valve. The
sample was flushed from the heart-cut loops into the cell by an isocratic
pump. Samples were then irradiated using different time intervals
and subsequently transferred by the same isocratic pump to a second-dimension
sample loop. The mixture containing the transformation products was
then subjected to the second-dimension separation. In the current
setup, about 30–40% of the selected fraction was transferred.
Multiple degradation products could be monitored. Degradation was
found to be faster when a smaller sample amount was introduced (0.3
μg as compared to 1.5 μg). The system was tested with
three applications, that is, fuchsin, a 19th-century synthetic organic
colorant, annatto, a lipophilic food dye, and vitamin B complex.
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