Image Credit: TOFWERK
The unsaturated, long-chain fatty acids plentiful in fish oil products have been found to be highly vulnerable to oxidation processes.
This article outlines the utilization of a TOFWERK Vocus PTR-TOF for online monitoring of volatile fish oil oxidation byproducts in capsuled fish oil.
No pretreatment or sample preparation is required by this technique, which can be employed to non-invasively evaluate levels of fish oil degradation throughout processes of production or for high-throughput investigation of product samples.
Two series of measurements were carried out. For the first measurement, fish oil was taken from the capsules, deposited in temperature regulated vials (30 °C), and subjected to significant ozone concentrations to replicate atmospheric oxidation.
A Vocus PTR-TOF repeatedly sampled the headspace of the vials to track the quick development of oxidation products. In the second investigation, the same quantity of capsule fish oil was deposited inside a new, translucent bottle each day for six days consecutively, and was sealed at room temperature with ambient air.
After the sixth day, the headspace of each of the six bottles was quantified by the Vocus PTR-TOF to identify aging and oxidation products as a function of time.
Figure 1 describes the efficient development of specific volatile oxidation byproducts in the headspace of capsuled fish oil in the minutes after ozone infusion. The majority of the oxidation products developed seconds following ozone treatment.
Figure 1. Continuous measurement of oxidation byproducts in the headspace of fish oil before and after ozone treatment. Most of the oxidation products emerged seconds after ozone infusion. Image Credit: TOFWERK.
Figure 2 collates the concentrations of a wider range of oxidation byproducts in the fish oil headspace prior to and following the ozone injection.
The amount of acetone (resp-propanal) and acetaldehyde increased by factors of ~50 and ~8, respectively.
Further large peaks controlling the O3-treated mass spectra were characterized as the known degradation byproducts butanal, hexenal, and propanediol.
The injection of ozone also caused huge increases in large oxygenated species, like nonanedione, nonanal, and nonenal.
Compared to the typical VOCs which can emerge from a range of sources, these more functionalized molecules with a higher molecular weight can function as unique identifiers for identifying the extent of degradation in fish oil.
Figure 2. Concentration of selected oxidation byproducts measured in the headspace of fish oil before and after ozone treatment. The oxidation produced many high molecular weight functionalized compounds that can serve as unique traces for diagnosing fish oil degradation. Image Credit: TOFWERK.
Figure 3 presents the concentration of specific volatile species from samples aged within ambient environments for extending numbers of days. The concentration of each species is positively correlated with the duration of aging. Certain VOCs plateaued before others, likely as a result of the different degradation pathway used.
Various external factors, for example humidity, temperature, ozone, and radiation, are understood to strongly impact the headspace composition of aged samples. A systematic investigation including all experimental stimulus is likely to specify quantitative and qualitative VOC markers for the oxidation of unsaturated fatty acids in fish oil.
Figure 3. Concentration of oxidation byproducts in the headspace of fish oil stored under closed ambient air for an increasing number of days. The concentrations of all species are positively correlated with the aging time but plateau at different rates. Image Credit: TOFWERK.
Produced from materials originally authored by Wen Tan, Veronika Pospisilova, Liang Zhu and Felipe Lopez-Hilfiker from TOFWERK.
TOFWERK is a global leader in time-of-flight mass spectrometry, delivering sensitive instruments for laboratory, industrial, and field analyses. Our customers’ interests range from materials science and geochemistry to metabolomics and trace-gas
TOFWERK engineers and scientists collaborate with research laboratories and OEM customers to develop custom MS solutions based on our modular design platform. This platform enables rapid design and manufacturing of novel instrumentation for research laboratories and OEM customers.
Our end-user product line includes the icpTOF, Vocus PTR-TOF, IMS-TOF, and EI-TOF for GC. These mass spectrometers bring the speed and sensitivity of TOFMS to many disciplines and sample types.
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