Degradation Products Of Antioxidants Research Articles

Comparative analysis of additive decomposition using one-dimensional and two–dimensional gas chromatography: Part II - Irgafos 168 and zinc stearate

Plastic production has experienced a significant increase in the last sixty years due to its cost-efficiency and adaptable characteristics, leading to the extensive use of additives to improve its performance and longevity. Due to the high demand for plastic, plastic waste production has increased, contaminating the environment and living beings by leaching additives, among other substances. Pyrolysis stands out among recycling techniques because it can handle mixed polymer waste feedstock. However, understanding the pyrolyzates distribution of additives is fundamental to assessing pyrolysis process of plastic waste. This study investigated the pyrolysis product distributions of two commonly used antioxidants, namely, Irgafos 168 and zinc stearate (ZnSt), using one-dimensional gas chromatography equipped with a quadruple mass spectrometer (GC–MS) and two-dimensional gas chromatography coupled to flame ionization detector and time–of–flight mass spectrometer (GC×GC–FID/TOF–MS). While GC separation technique provided limited information on product distribution, GC×GC offered enhanced resolution and identification of the decomposition products. In the pyrolysis of Irgafos 168 at 550 °C, GC identified 18 products, while GC×GC identified 198 products, representing an increase of approximately 11-fold. Similarly, for ZnSt, GC identified 67 products, while GC×GC identified 434 products, representing a 6-fold increase. GC×GC identified decomposition products from 15 different chemical classes for Irgafos 168 and 16 chemical classes for ZnSt, compared to 4 and 11 chemical classes identified by GC, respectively. Phenols and their derivatives were the major chemical class in the decomposition products of Irgafos 168 with a yield of 9.51 wt.%. In contrast, olefinic products were the dominant ones for ZnSt, with a yield of 9.73 wt.%. The major decomposition product of Irgafos 168 and ZnSt was 2‑tert‑butyl‑methylphenol (C11H16O) and C6 olefin (C6H12) with yields of 3.88 wt.%, and 1.13 wt.%, respectively. Utilizing the GC×GC separation method improved the ability to identify decomposition products, which can ultimately lead to a better understanding of antioxidant degradation that occurs during the pyrolysis process. GC×GC also provided thorough characterization of minor and co-eluted products along with major antioxidant degradation products. Additionally, the decomposition product distribution of Irgafos 168 and ZnSt was also compared with the primary antioxidants, Irganox 1010, Irganox 1076, and BHT, studied in part 1. The analysis indicated that the olefinic chemical class was the predominant one in Irganox 1010, Irganox 1076, and ZnSt, while ketones were the major chemical class in the decomposition of BHT and phenolics had the highest yield in Irgafos 168.

Screening and safety assessment of migrating substances released from biodegradable packaging materials into milk

Biodegradable polymeric packaging materials are being studied for their potential to replace traditional petroleum-based ones for food contact applications. However, potential safety concerns associated with the utilization of these biodegradable polymers have not been studied in detail. In this study, we conducted non-targeted screening and migration studies on two types of biodegradable milk packaging materials, which were composed of a mixture of polylactic acid (PLA), poly(butylene adipate-co-terephthalate) (PBAT), polybutylene succinate (PBS), and cellulose. In particular, we monitored the transfer of migrating substances from the packaging materials into a food simulant (50% ethanol) and into a real food (fat free and whole milk). A screening study identified seven compounds in the biodegradable packaging bags, including degradation products of antioxidants, lubricants, and plasticizers such as triethylene glycol, diethyl succinate, glycerin, 2,4-di-tert-butylphenol, and 13-docosenamide were identified. The migration studies indicated that the types and amounts of migrating substances transferred into the real food were appreciably lower than those transferred into the food simulant. Most of the detected migrating substances were below the levels established in the European Union regulations. However, the triethylene glycol levels (68-144 mg/kg) in the food simulant exceeded the limits (60 mg/kg) for one of the packaging materials tested. A safety assessment suggested that there is a low level of safety risk associated with one of the biodegradable packaging materials. This study provides important insights into the safety of biodegradable packaging materials that might be used in the food industry.

Comparison of migration and cumulative risk assessment of antioxidants, antioxidant degradation products, and other non-intentionally added substances from plastic food contact materials

Antioxidants are used in the production of synthetic resins to prevent oxidative degradation. However, non-intentionally added substances (NIAS) and the degradation products of antioxidants may contaminate food contact materials (FCM) and migrate into food. Herein, NIAS and antioxidant degradation products in synthetic resins and their migration into food simulants under various conditions were evaluated. Risk assessment was performed based on the toxicity reference values or with threshold of toxicological concern (TTC) approach. The antioxidant degradation products migrated mainly to fatty-food simulants, with the highest migration in isooctane, followed by n-heptane (similar to or lower than isooctane) and 95 % ethanol. Especially, the migration of 2,4-di-tert-butylphenol was high when the FCM was used for the first time under daily use conditions such as ultraviolet sterilization or heating in a pot, oven, or microwave. In addition, 36 target substances were monitored in 142 products of 18 synthetic resins. Of these, 2,4-di-tert-butylphenol was most sensitively detected. Risk assessment demonstrated that all the investigated substances were below the toxicity reference values. However, the risk associated with polyethylene was relatively high compared to other synthetic resins. The cumulative risks of oxidizing Irgafos 168, (z)−9-octadecenamide, tri-o-tolyl phosphite, tri-p-tolyl phosphite, and 7,9-di-tert-butyl-1-oxaspiro(4,5)deca-6,9-diene-2,8-dione using the TTC approach were calculated to range from 34.81 % to 73.74 %, suggesting that the TTC is a more conservative risk assessment.

Divergent Forms of Pyroplastic: Lessons Learned from the M/V X-Press Pearl Ship Fire.

In late May 2021, the M/V X-Press Pearl container ship caught fire while anchored 18 km off the coast of Colombo, Sri Lanka and spilled upward of 70 billion pieces of plastic or "nurdles" (∼1680 tons), littering the country's coastline. Exposure to combustion, heat, chemicals, and petroleum products led to an apparent continuum of changes from no obvious effects to pieces consistent with previous reports of melted and burned plastic (pyroplastic) found on beaches. At the middle of this continuum, nurdles were discolored but appeared to retain their prefire morphology, resembling nurdles that had been weathered in the environment. We performed a detailed investigation of the physical and surface properties of discolored nurdles collected on a beach 5 days after the ship caught fire and within 24 h of their arrival onshore. The color was the most striking trait of the plastic: white for nurdles with minimal alteration from the accident, orange for nurdles containing antioxidant degradation products formed by exposure to heat, and gray for partially combusted nurdles. Our color analyses indicate that this fraction of the plastic released from the ship was not a continuum but instead diverged into distinct groups. Fire left the gray nurdles scorched, with entrained particles and pools of melted plastic, and covered in soot, representing partial pyroplastics, a new subtype of pyroplastic. Cross sections showed that the heat- and fire-induced changes were superficial, leaving the surfaces more hydrophilic but the interior relatively untouched. These results provide timely and actionable information to responders to reevaluate cleanup end points, monitor the recurrence of these spilled nurdles, gauge short- and long-term effects of the spilled nurdles to the local ecosystem, and manage the recovery of the spill. These findings underscore partially combusted plastic (pyroplastic) as a type of plastic pollution that has yet to be fully explored despite the frequency at which plastic is burned globally.

Identification of Potential Migrants in Polyethylene Terephthalate Samples of Ecuadorian Market.

Polyethylene terephthalate (PET) is the plastic packaging material most widely used to produce bottles intended for contact with food and beverages. However, PET is not inert, and therefore, some chemical compounds present in PET could migrate to food or beverages in contact, leading to safety issues. To evaluate the safety of PET samples, the identification of potential migrants is required. In this work, eight PET samples obtained from the Ecuadorian market at different phases of processing were studied using a well-known methodology based on a solvent extraction followed by gas chromatography–mass spectrometry analysis and overall migration test. Several chemical compounds were identified and categorized as lubricants (carboxylic acids with chain length of C12 to C18), plasticizers (triethyl phosphate, diethyl phthalate), thermal degradation products (p-xylene, benzaldehyde, benzoic acid), antioxidant degradation products (from Irgafos 168 and Irganox), and recycling indicator compounds (limonene, benzophenone, alkanes, and aldehydes). Additionally, overall migration experiments were performed in PET bottles, resulting in values lower than the overall migration limit (10 mg/dm2); however, the presence of some compounds identified in the samples could be related to contamination during manufacturing or to the use of recycled PET-contaminated flakes. In this context, the results obtained in this study could be of great significance to the safety evaluation of PET samples in Ecuador and would allow analyzing the PET recycling processes and avoiding contamination by PET flakes from nonfood containers.

Development of an accelerated artificial ageing method for the characterization of degradation products of antioxidants in lubricants by mass spectrometry.

The understanding of ageing mechanisms of antioxidants in base oils is indispensable for the development of improved lubricants. In this study, a novel artificial ageing method based on the application of peroxide as oxidant is presented for improved monitoring of thermo-oxidative degradation processes in combination with mass spectrometry. Model oils containing aminic and phenolic antioxidants were aged and chemical structures of their oxidation products were elucidated by ultrahigh performance liquid chromatography and electrospray ionization high resolution (Orbitrap) mass spectrometry. Additionally, synergistic mixtures of four antioxidants were investigated, because the formation of condensed molecules from amines and phenols would have a major influence on the antioxidant potential but could not be detected in the bulk lubricant.

Release of drinking water contaminants and odor impacts caused by green building cross-linked polyethylene (PEX) plumbing systems

Green buildings are increasingly being plumbed with crosslinked polyethylene (PEX) potable water pipe. Tap water quality was investigated at a six month old plumbing system and chemical and odor quality impacts of six PEX pipe brands were examined. Eleven PEX related contaminants were found in the plumbing system; one regulated (toluene) and several unregulated: Antioxidant degradation products, resin solvents, initiator degradation products, or manufacturing aides. Water chemical and odor quality was monitored for new PEX-a, -b and -c pipes with (2 mg/L free chlorine) and without disinfectant over 30 days. Odor and total organic carbon (TOC) levels decreased for all pipes, but odor remained greater than the USA's Environmental Protection Agency's (USEPA) secondary maximum contaminant level. Odors were not attributed to known odorants ethyl-tert-butyl ether (ETBE) or methyl-tert-butyl ether (MTBE). Free chlorine caused odor levels for PEX-a1 pipe to increase from 26 to 75 threshold odor number (TON) on day 3 and affected the rate at which TOC changed for each brand over 30 days. As TOC decreased, the ultraviolet absorbance at 254 nm increased. Pipes consumed as much as 0.5 mg/L as Cl2 during each 3 day stagnation period. Sixteen organic chemicals were identified, including toluene, pyridine, methylene trichloroacetate and 2,4-di-tert-butylphenol. Some were also detected during the plumbing system field investigation. Six brands of PEX pipes sold in the USA and a PEX-a green building plumbing system impacted chemical and drinking water odor quality.

Phthalates and Other Plastic Additives in Surface Sediments of the Cross River System, S.E. Niger Delta, Nigeria: Environmental Implication

Quantitative determination of phthalates and other plastic additives was carried out using GC-MS in order to understand the distribution and fate of these compounds in surface sediments of the Cross River System. Results show the concentration ranges (mean±standard deviation) of the three phthalates as: di(ethylhexyl)phthalate (DEHP; 1.97– 86.76 [24.06 ± 29.88 mg/kg dry weight dw]); di(n-butyl)phthalate (DnBP; 0.16 – 17.41 [3.25 ± 5.03 mg/kg dw]); di(isobutyl)phthalate (DiBP; 1.14 – 29.64 [9.82 ± 10.23 mg/kg dw]). However, examination of n-hexane procedural blank (used also in the study for clean-up protocol) GC trace revealed the presence of certain amounts of DEHP and tris-2,6-di(t-butyl)phenylphosphite (PhP) which interfere with the targeted analytes. Therefore, extract/blank (E/B) ratios were calculated and were in the range 1.05 – 12.54, indicating that the concentrations of DEHP and PhP previously assigned to the sediments were partly derived from laboratory artifacts. Differences in grain size distribution, partitioning behavior, volatility and solubility in the aqueous phase as well as localized influx may account for the observed spatial variation of phthalates and other plastic additives in the river system. The primary sources of these phthalates and tris-2,6-di(t-butyl)phenylphosphate (PhP’) were considered to be the result of direct discharge of untreated effluent/solid waste and emission arising from burning of refuse containing plastic materials, respectively. The occurrence of certain anti-oxidant degradation products in sediments (not in the blank) such as 2,6-di(t-butyl)-4-hydroxybenzaldehyde (HBA) and 2,6-di(t-butyl)quinine (Qn) and PhP’ (a compound proposed here as a possible marker for plastic combustion for the region/air basin), suggests that phthalates contamination had occurred before sample contact with laboratory artifacts.

Ultrahigh‐performance liquid chromatography/electrospray ionization linear ion trap Orbitrap mass spectrometry of antioxidants (amines and phenols) applied in lubricant engineering

For the qualification and quantification of antioxidants (aromatic amines and sterically hindered phenols), most of them applied as lubricant additives, two ultrahigh-performance liquid chromatography (UHPLC) electrospray ionization mass spectrometric methods applying the positive and negative ion mode have been developed for lubricant design and engineering thus allowing e.g. the study of the degradation of lubricants. Based on the different chemical properties of the two groups of antioxidants, two methods offering a fast separation (10 min) without prior derivatization were developed. In order to reach these requirements, UHPLC was coupled with an LTQ Orbitrap hybrid tandem mass spectrometer with positive and negative ion electrospray ionization for simultaneous detection of spectra from UHPLC-high-resolution (HR)-MS (full scan mode) and UHPLC-low-resolution linear ion trap MS(2) (LITMS(2)), which we term UHPLC/HRMS-LITMS(2). All 20 analytes investigated could be qualified by an UHPLC/HRMS-LITMS(2) approach consisting of simultaneous UHPLC/HRMS (elemental composition) and UHPLC/LITMS(2) (diagnostic product ions) according to EC guidelines. Quantification was based on an UHPLC/LITMS(2) approach due to increased sensitivity and selectivity compared to UHPLC/HRMS. Absolute quantification was only feasible for seven analytes with well-specified purity of references whereas relative quantification was obtainable for another nine antioxidants. All of them showed good standard deviation and repeatability. The combined methods allow qualitative and quantitative determination of a wide variety of different antioxidants including aminic/phenolic compounds applied in lubricant engineering. These data show that the developed methods will be versatile tools for further research on identification and characterization of the thermo-oxidative degradation products of antioxidants in lubricants.

HS-SPME-GC-MS analysis of antioxidant degradation products migrating to drinking water from PE materials and PEX pipes

Polyethylene (PE) and cross-linked polyethylene (PEX) pipes are frequently used in water supply systems. Such pipes contain added antioxidants with phenolic structures, e.g. Irgafos 168, Irganox 1010 and 1076, in order to improve durability. However, phenol, ketone and quinone antioxidant degradation products may leach and enter drinking water. The aim of this investigation was to develop a method for measuring these degradation products with a performance meeting the drinking water quality criteria of 20 µg L−1. Using headspace solid phase microextraction coupled to a gas chromatograph with a mass spectrometer, a method was established revealing limits of detection and quantification less than 0.4 and 1 µg L−1 respectively. The method was applied to migration experiments for two PEX pipes and one PE material, quantifying the release of two degradation products. Highest concentrations were observed for 2,6-di-tert-butyl-p-benzoquinone which in one of the two pipes was found in concentrations of 18–57 µg L−1 in each of eight consecutive release experiments.

Screening for antiradical efficiency of 21 semi-synthetic derivatives of quercetin in a DPPH assay

The group of 21 novel semi-synthetic derivatives of quercetin was screened for the antiradical efficiency in a DPPH assay. The initial fast absorbance decrease of DPPH, corresponding to the transfer of the most labile H atoms, was followed by a much slower absorbance decline representing the residual antiradical activity of the antioxidant degradation products. Initial velocity of DPPH decolorization determined for the first 75-s interval was used as a marker of the antiradical activity. Application of the kinetic parameter allowed good discrimination between the polyphenolic compounds studied. The most efficient chloronaphthoquinone derivative (compound Ia) was characterized by antiradical activity higher than that of quercetin and comparable with that of trolox. Under the experimental conditions used, one molecule of Ia was found to quench 2.6±0.1 DPPH radicals.

Antioxidant consumption in squalane and polyethylene exposed to chlorinated aqueous media

Squalane stabilized with 0.2 wt.% of Irganox 1010 and a medium-density polyethylene containing 0.1 wt.% of the same antioxidant were exposed to two different aqueous media (water solutions containing either 10 ppm Cl2 or 10 ppm ClO2, both buffered to pH = 6.8) at different temperatures between 30 and 70 °C. The squalane phase was characterized by differential scanning calorimetry (oxidation induction time, OIT) and infrared spectroscopy, and the aqueous media were analysed after concentrating the analytes using liquid–liquid extraction by liquid chromatography, mass spectrometry and infrared spectroscopy. OIT measurements were carried out on the polyethylene samples after exposure to the chlorinated aqueous media. Exposure of the squalane systems to water containing ClO2 resulted in discolouration by the formation of quinoid structures and a faster depletion of the antioxidant than exposure to water containing Cl2. The activation energy for the loss of antioxidant activity on exposure to ClO2-water was very low (<10 kJ mol−1) in the squalane test (no diffusion control) and 21 ± 2 kJ mol−1 at a depth of 1–2 mm from the surface of polyethylene plaques (diffusion control). Calculation from earlier published OIT data from a HDPE exposed to Cl2-water yielded an activation energy for the loss antioxidant activity of 68 kJ mol−1. The antioxidant degradation products obtained from the exposure to the ClO2 aqueous medium were found at a higher concentration, were more polar and exhibited a higher proportion of low molar mass species than those obtained after exposure to the Cl2 aqueous medium. The important chemical difference between ClO2 and Cl2 is that the former is a one-electron oxidant whereas the latter preferentially reacts by hydrogen substitution. Possible further reactions, in agreement with the observations made, are proposed.

CID of singly charged antioxidants applied in lubricants by means of a 3D ion trap and a linear ion trap–Orbitrap mass spectrometer

The aim of this study was to investigate the fragmentation behavior induced by low-energy collision-induced dissociation (LE-CID) of four selected antioxidants applied in lubricants, by two different types of ion trap mass spectrometers: a three-dimensional ion trap (3D-IT) and a linear IT (LIT) Orbitrap MS. Two sterically hindered phenols and two aromatic amines were selected as model compounds representing different antioxidant classes and were characterized by positive-ion electrospray ionization (ESI) and LE-CID. Various types of molecular ions (e.g. [M](+•) , [M + H](+) , [M + NH(4) ](+) or [M + Na](+) ) were used as precursor ions generating a significant number of structurally relevant product ions. Furthermore, the phenolic compounds were analyzed by negative-ion ESI. For both IT types applied for fragmentation, the antioxidants exhibited the same unusual LE-CID behavior: (1) they formed stable radical product ions and (2) CC bond cleavages of aliphatic substituents were observed and their respective cleavage sites depended on the precursor ion selected. This fragmentation provided information on the type of structural isomer usually not obtainable for branched aliphatic substituents utilizing LE-CID. Comparing the two instruments, the main benefit of applying the LIT-Orbitrap was direct access to elemental composition of product ions enabling unambiguous interpretation of fragmentation trees not obtainable by the 3D-IT device (e.g. loss of isobaric neutrals). It should be emphasized that the types of product ions formed do not depend on the type of IT analyzer applied. For characterizing degradation products of antioxidants, the LIT-Orbitrap hybrid system, allowing the determination of accurate m/z values for product ions, is the method of choice.

Experience with the application of the draft European Standard prEN 15768 to the identification of leachable organic substances from materials in contact with drinking water by GC-MS

In this work, the draft European Standard prEN 15768 “The GC-MS identification of water leachable organic substances from materials in contact with water intended for human consumption” was applied to test 17 different commonly used plastic pipes for domestic plumbing systems for the migration of unexpected substances into drinking water. The tested pipes were made from 8 different plastic materials. Substances detected in the migration waters from the different pipe materials at concentrations exceeding 2 μg l−1 are reported. More than 60% of them could be identified by library search with the NIST mass spectral database. The migrated substances found and identified are discussed concerning their concentration trends with increasing time of testing. A significant number of substances identified were degradation products of antioxidants that are used as additives for the plastic materials. Possible degradation pathways for important antioxidants leading to frequently identified substances like 2,4-di-tert-butylphenol, 3-(3,5-di-tert-butyl-4-hydroxy-phenyl) propanoic acid, 7,9-di-tert-butyl-1-oxaspiro(4,5)deca-6,9-diene-2,8-dione, 3,5-di-tert-butyl-4-hydroxybenzaldehyde, and 2,6-di-tert-butyl-p-benzoquinone are proposed and discussed. As a conclusion, this study showed a good performance of the preliminary standard in practice.

Identification of degradation products of antioxidants in polyolefins by liquid chromatography combined with atmospheric pressure photoionisation mass spectrometry

Round robin tests have revealed the trend that the concentration of stabilizers in polyolefins is usually underestimated. However, it is still unclear whether this underestimation is due to systematic errors of the analysis procedures or to degradation of the stabilizers during the production of the round robin sample itself. Within the present work, the degradation pathways of six common antioxidants (ADK Stab AO-60, Everfos 168, Kinox 30, Irganox 3114, Irganox 1076, and Cyanox 1790) were investigated. Methods based on high-performance liquid chromatography with UV detection or hyphenated with mass spectrometry (employing either an ion trap or a quadrupole/time-of-flight instrument) were developed, whereby the suitability of atmospheric pressure photoionisation was studied and compared with the performance of more established ionisation techniques like electrospray ionisation and atmospheric pressure chemical ionisation. While ADK Stab, Kinox 30, Everfos 168, and Irganox 1076 turned out to be thermally stable at 115 °C, Irganox 3114 and Cyanox 1790 were partly degraded by oxidation. In the presence of talcum, which is a widely used inorganic filler for polyolefins, additional degradation reactions such as the cleavage of ester bonds and the loss of tert-butyl groups were observed at elevated temperature.

Analysis of the Volatile Organic Matter of Engine Piston Deposits by Direct Sample Introduction Thermal Desorption Gas Chromatography/Mass Spectrometry

This article establishes an alternative method for the characterization of volatiles organic matter (VOM) contained in deposits of the piston first ring grooves of diesel engines using a ChromatoProbe direct sample introduction (DSI) device coupled to gas chromatography/mass spectrometry (GC/MS) analysis. The addition of an organic solvent during thermal desorption leads to an efficient extraction and a good chromatographic separation of extracted products. The method was optimized investigating the effects of several solvents, the volume added to the solid sample, and temperature programming of the ChromatoProbe DSI device. The best results for thermal desorption were found using toluene as an extraction solvent and heating the programmable temperature injector from room temperature to 300 degrees C with a temperature step of 105 degrees C. With the use of the optimized thermal desorption conditions, several components have been positively identified in the volatile fraction of the deposits: aromatics, antioxidants, and antioxidant degradation products. Moreover, this work highlighted the presence of diesel fuel in the VOM of the piston deposits and gave new facts on the absence of the role of diesel fuel in the deposit formation process. Most importantly, it opens the possibility of quickly performing the analysis of deposits with small amounts of samples while having a good separation of the volatiles.

Determination of the concentration profile and homogeneity of antioxidants and degradation products in a cross-linked polyethylene type A (PEXa) pipe

A solvent extraction technique has been developed to determine the concentration profile of two antioxidants and five degradation products of antioxidants in cross-linked polyethylene (PEX) materials. Irganox ® 1076 and two degradation products in a PEX pipe type A (PEXa) were detected after extraction in chloroform. Fick's second law of diffusion was used to verify that 24 h of extraction at room temperature was sufficient to extract Irganox ® 1076 and the degradation products from PEX materials with a thickness of 5 μm. With the use of gas chromatography and mass spectrometry, the concentration profile was measured at four different places on a 100 m PEXa pipe. A two-way ANOVA analysis showed that the composition of Irganox ® 1076 was homogenous in the radial direction and heterogeneous in the longitudinal direction. Two degradation products of antioxidants were detected, 2,6-di- tert-butyl- p-benzoquinone and 2,4-di- tert-butyl phenol. The composition of 2,6-di- tert-butyl- p-benzoquinone was found to be homogeneous in the radial and longitudinal direction. 2,4-Di- tert-butyl phenol was homogeneous in the radial direction but heterogeneous in the longitudinal direction.

Solid-phase microextraction for qualitative and quantitative determination of migrated degradation products of antioxidants in an organic aqueous solution

Low molecular weight aromatic substances may migrate out from plastic packaging to their contents, especially if they consist of organic aqueous solutions or oils. It is, therefore, extremely important to be able to identify and quantify any migrated substances in such solutions, even at very low concentrations. We have in this work investigated and evaluated the use of solid-phase microextraction for the specific task of extraction from an organic aqueous solution such as a simulated pharmaceutical solution consisting of 10 vol.% ethanol in water. The goal was furthermore to investigate the possibility of simultaneously identifying and quantifying the substances in spite of differences in their chemical structures. Methods were developed and evaluated for extraction both with direct sampling and with headspace sampling. Difficulties appeared due to the ethanol in the solution and the minute amounts of substances present. We have shown that a simultaneous quantification of migrated low molecular weight degradation products of antioxidants using only one fibre is possible if the extraction method and temperature are adjusted in relation to the concentration levels of the analytes. Comparions were made with solid-phase extraction.

Functionality changes of natural antioxidants during food processing and storage

Food raw materials and products contain inhibitors of oxidation reactions, both in the lipidic phase and the aqueous phase. The most important inhibitors are phenolic antioxidants. During food processing and storage, concentrations of antioxidants in the two phases reach an equilibrium. Phenolics react with lipidic free radicals, being converted into antioxidant free radicals, quinones, polymers and copolymers. Some degradation products possess an antioxidant activity, too. The relative antioxidant activity decreases with decreasing concentration of oxygen in the system and with increasing temperature. Antioxidants are more rapidly decomposed in surface layers. Health aspects of antioxidant degradation products are often neglected as the safety of antioxidant degradation products is mostly unknown.

酸化防止剤含有ポリエチレン, ポリプロピレン及びポリスチレンに対するガンマ線照射の影響

The polyethylene (PE), polypropylene (PP) and polystyrene (PS) films and sheets were made with antioxidants, and the contents of additives, volatiles and other chemicals, tensile strength, color and odor were tested after gamma irradiation of 0, 10, 30 and 50 kGy dose. The antioxidants decreased uponradiation, BHT and Irgafos 168 disappeared more rapidly than Irganox 1076 and 1010. The degradation products of polymer, such as acetic acid, propionic acid, 2-methyl-2-propanol and 2, 2-dimethylpropanoic acid, were produced more in PP than PE, and the presence of antioxidants reduced their formation.On the other hand, 2, 4-di-tert-butylphenol and 2, 6-di-tert-butyl-1, 4-benzoquinone were found as degradation products of antioxidants. PP films became fragile upon irradiation and even a high level of BHT could not protect, while the combination of three antioxidants was more effective. Coloration was more pronounced, and odors were stronger in the films containing BHT. In PS sheets, the antioxidants decreased only slowly and the degradation product was formed only in small amounts.