Ultrasensitive SERS quantitative detection of antioxidants via diazo derivatization reaction and deep learning for signal fluctuation mitigation.

Synthetic antioxidants serve as essential protectors against oxidation and deterioration of edible oils, however, prudent evaluation is necessary regarding potential health risks associated with excessive intake. The direct adsorption of antioxidants onto conventional surface-enhanced Raman scattering (SERS) substrates is challenging due to the presence of phenolic hydroxyl groups in their molecular structures, resulting in weak Raman scattering signals and rendering direct SERS detection difficult. In this study, a diazo derivatization reaction was employed to enhance SERS signals by converting antioxidant molecules into azo derivatives, enabling the amplification of the weak Raman scattering signals through the strong vibrational modes induced by the N = N double bond. The resulting diazo derivatives were characterized using UV-visible absorption and infrared spectroscopy, confirming the occurrence of diazo derivatization of the antioxidants. The proposed method successfully achieved the rapid detection of three commonly used synthetic antioxidants, namely butylated hydroxyanisole (BHA), tert-butylhydroquinone (TBHQ), and propyl gallate (PG) on interfacial self-assembled gold nanoparticles. Furthermore, rapid predictions of BHA, PG, and TBHQ within the concentration range of 1 × 10-6 to 2 × 10-3 mol/L were achieved by integrating a convolutional neural network model. The predictive range of this model surpassed the traditional quantitative method of manually selecting characteristic peaks, with linear coefficients (R2) of 0.9992, 0.9997, and 0.9997, respectively. The recovery of antioxidants in real soybean oil samples ranged from 73.0 % to 126.4 %. Based on diazo derivatization, the proposed SERS method eliminates the need for complex substrates and enables the analysis and determination of synthetic antioxidants in edible oils within 20 min, providing a convenient analytical approach for quality control in the food industry.

Preparation and structural characterization of epoxidized soybean oils-based pressure sensitive adhesive grafted with tea polyphenol palmitate.

Vegetable oils-based pressure sensitive adhesives (PSAs) are green and sustainable but face unsatisfactory adhesion strengths and are prone to aging during storage and application due to the existence of residual double bonds and massive ester bonds. Nine common antioxidants (tea polyphenol palmitate (TPP), caffeic acid, ferulic acid, gallic acid, butylated hydroxytoluene, tertiary butylhydroquinone, butylated hydroxyanisole, propyl gallate, and tea polyphenols) were grafted into epoxidized soybean oils-PSA (ESO-PSA) system to enhance antiaging properties and adhesion strengths. Results showed ESO-PSAs grafted with caffeic acid, tertiary butylhydroquinone, butylated hydroxyanisole, propyl gallate, tea polyphenols, or TPP didn't occur failure with TPP having best performance. The optimal conditions were ESO reacted with 0.9 % TPP, 70 % rosin ester, and 7.0 % phosphoric acid at 50 °C for 5 min, under which peel strength and loop tack increased to 2.460 N/cm and 1.66 N, respectively, but peel strength residue reduced to 138.09 %, compared with control (0.407 N/cm, 0.43 N, and 1669.99 %). Differential scanning calorimetry and thermogravimetric results showed TPP grafting increased the glass transition temperature of ESO-PSA slightly but improved its thermal stability significantly. Fourier transform infrared spectroscopy and 1H nuclear magnetic resonance results showed TPP, phosphoric acid, and rosin ester all partially participated in the covalently crosslinking polymerization of ESO-PSAs and the rest existed in the network structures in the free form.

A polypyrrole-cotton pad sorbent as micro-solid phase extractor enclosed in tea bag envelope for determination of synthetic antioxidants in non-alcoholic beverage products.

A polypyrrole (PPy)-cotton pad sorbent enclosed in tea bag envelope was developed and used in micro-solid phase extraction (µ-SPE) for the determination of butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT). After extraction, the extract was qualified and quantified by a gas chromatograph equipped with a flame ionization detector (GC-FID). Parameters influencing this developed method and the efficiency of µ-SPE were studied and optimized. Under the optimal conditions, the developed method provided good linearity in a concentration range of 0.100-100 µg L-1 for BHA and 0.050-50 µg L-1 for BHT, respectively. The limits of detection were 39.27 ± 0.52 ng L-1 for BHA and 16.96 ± 0.17 ng L-1 for BHT. Satisfactory relative recoveries of BHA and BHT were achieved in the range from 86.8 ± 1.9 to 117.1 ± 2.3% with acceptable relative standard deviation (RSD) below 8.1%. Good reproducibility was obtained with RSDs < 3.1%, for n = 6. The developed adsorbent is easy to operate, low cost, eco-friendly, reusable, with high extraction efficiency, and was successfully applied in the simultaneous synthetic antioxidant determination of non-alcoholic beverage samples.

Colorimetric sensor array based on CoOOH nanoflakes for rapid discrimination of antioxidants in food.

The identification of synthetic antioxidants has considerable significance in food safety. Here, we described the development of a colorimetric sensor array for rapid detection of eight antioxidants in food through the redox reaction between CoOOH and antioxidants in the presence of colorimetric signal indicators. The CoOOH nanoflakes exhibited high catalytic oxidation activity and can independently catalyze oxidation signal indicators showing different colors. The color reaction was inhibited to different degrees in the presence of antioxidants, which resulted in distinct signal response patterns for their discrimination. The method showed good linearity in the range from 50 to 1000 nM for butylated hydroxytoluene (BHT), butylhydroxyanisole (BHA), propyl gallate (PG) and tert-butyl hydroquinone (TBHQ). Moreover, different proportions of antioxidants were located in the middle pattern of each single antioxidant, and showed certain linear relationships among different concentration ratios. Finally, the proposed colorimetric sensor array was used for practical applications where TBHQ and BHT were detected in biscuits and sausages, and BHA and PG were detected in fried pork kebabs, respectively. The results were further confirmed by high-performance liquid chromatography, which demonstrated the great potential of the colorimetry sensor array for practical applications.

[Study of Rapid HPLC Method for the Determination of Antioxidants in Foods, and Standard Solution Stability during Storage].

In this study, we simultaneously determined three antioxidants, butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA), and tert-butylhydroquinone (TBHQ), using HPLC equipped both with a photodiode array detector and a fluorescence detector in 25 minutes per sample. Due to the combined use of the two detectors, we could achieve improved target selectivity. Further, quantification at the specific wavelengths for each target substance particularly increased BHT detection sensitivity. This approach enabled us to avoid repeated measurements during daily inspections. Furthermore, detections were performed using LC-MS/MS instead of GC-MS to overcome the problem of helium gas shortage.In addition, we investigated antioxidant stability in standard solutions during storage. Although TBHQ was stable in methanol with ascorbic acid at -20℃, ascorbic acid storage has possibility to lead to decrease in BHT and BHA concentrations. We recognized that the mixture of BHT and BHA dissolved in methanol at 4℃ and that of BHT, BHA and TBHQ dissolved in methanol with ascorbic acid at -20℃ were suitable for about one year.

Migration analysis, antioxidant, and mechanical characterization of polypropylene-based active food packaging films loaded with BHA, BHT, and TBHQ.

Polypropylene (PP) based active composite films were prepared by adding butylated hydroxy anisole (BHA), butylated hydroxytoluene (BHT), and tertiary butylated hydroquinone (TBHQ) antioxidants using the extrusion molding process. All concentrations of BHT, 2% to 3% BHA, and 3% TBHQ significantly increased the tensile strength (TS) of the composite films compared with control films. Increasing antioxidant concentration decreased TS values for BHT films, whereas an opposite trend was observed for BHA and TBHQ films. BHA at < 2%, BHT at > 2%, and TBHQ at all added concentrations significantly reduced elongation at break (Eb ) of the composite films compared to control films. Water vapor permeability (WVP) of 1% BHT film was not significantly different from control. However, other antioxidants especially at increased concentrations significantly increased WVP values. TBHQ films with 300% to 662% increase had the highest WVP and BHT films with 5% to 81% increase had the lowest WVP among composite films. All three antioxidants had a negative effect on the transparency of the films; however the effect of BHA at higher concentrations was greater. The antioxidants did not change the color attributes of the films. Films containing all antioxidants showed 2,2-diphenyl-1-picrylhydrazyl radical-scavenging activity, which increased with increase in their concentration, especially for those containing 3 wt.% BHT and TBHQ. Overall, incorporating BHA and BHT into a PP matrix improved mechanical, barrier, antioxidant properties, and film appearance and consequently were proposed for the development of antioxidant active PP films. TBHQ film is not recommended for food packaging because of its weak mechanical properties (lower Eb and TS values, higher WVP, and greater migration).

Comparative study of rosemary extracts and several synthetic and natural food antioxidants. Relevance of carnosic acid/carnosol ratio.

The antiradical power, at equal concentrations of active principles, of the following antioxidants were studied using the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) assay: butylated-hydroxyanisole, butylated-hydroxytoluene, tert-butylhydroquinone, ascorbyl palmitate, tocopherol, grape seed extract, olive extract and five rosemary extracts with different concentrations of carnosic acid (CA) and carnosol (COL). The reaction kinetics of DPPH scavenging activity in each studied substance identified significant variations in the time needed to reach the steady state. Rosemary extracts were seen to be more effective than the other compounds. CA had higher antioxidant activity than COL, although COL seemed to react faster with DPPH. The relevance of the CA/COL ratio for the antioxidant activity of rosemary extracts was also analysed. The presence of COL in rosemary extracts increased the antioxidant activity with an optimal CA/COL ratio of 2.5-3.0. Olive extract and grape seed extract seem to be very promising additives for use as technological antioxidants.

Migration Study of Butylated Hydroxytoluene and Irganox 1010 from Polypropylene Treated with Severe Processing Conditions.

Safety concerns have emerged over the increased use of polypropylene (PP) in food-packaging markets. Some antioxidants in PP can migrate to foods and cause undesirable effects in humans. In this study, migration behaviors of butylated hydroxytoluene (BHT) and Irganox 1010 (I-1010) in PP sheets were determined according to the US FDA migration test conditions. In particular, we tested the effects of severe conditions of food processing and storage, such as autoclave heating (sterilization at about 121 °C), microwave radiation (700 W), and deep freezing (-30 °C) on migration of antioxidants. Migrant concentrations were higher in 95% ethanol as lipid food simulant, because of the hydrophobic nature of both PP and antioxidants. Autoclave heating treatment increased migrant concentrations compared with other processing conditions. Moreover, increased migrant concentrations by deep freezing condition were attributed to the brittleness of PP at freezing temperature. Regardless of processing conditions, BHT which has a lower molecular weight, migrated faster than I-1010. PRACTICAL APPLICATION: The antioxidants with hydrophobic nature such as butylated hydroxytoluene (BHT) and Irganox 1010 (I-1010) in polypropylene sheets would be migrated to foods, which is an important issue for industrial production food packaging materials. Migration behavior was promoted by severe processing conditions such as autoclave heating, microwave radiation, freezing, and especially autoclave heating treatment led the highest migration among them. Therefore, control of chemical additive migration from polypropylene food packaging is needed for safe food processing.

A stir foam composed of graphene oxide, poly(ethylene glycol) and natural latex for the extraction of preservatives and antioxidant.

A stir foam composed of graphene oxide, poly(ethylene glycol) and natural latex (GO-PEG-NL) was prepared for use in micro-solid phase extraction sorbent of preservative agents and antioxidants from cosmetic products. The extracted analytes were quantified by GC-MS. Under the optimized conditions, the calibration plots are linear in the concentration ranges between 5.0 µg·L-1 to 1.0 mg·L-1 for benzoic acid, of 10.0 µg·L-1 to 1.0 mg·L-1 for 2-methyl-3-isothiazolinone (MI), and between 1.0 µg·L-1 and 1.0 mg·L-1 for both 3-tert-butyl-4-hydroxyanisole (BHA) and 2,6-di-tert-butyl-p-hydroxytoluene (BHT). The LODs are 1.0 µg·L-1 for benzoic acid, 5.0 µg·L-1 for MI and 0.5 µg·L-1 for both BHA and BHT. The stir-foam can be easily prepared, is inexpensive and well reproducible (RSDs <3%, for n = 6). It can be re-used for up to 12 times after which extraction efficiency has dropped to 90%. The method was successfully applied to the determination of preservatives and antioxidants in cosmetic samples. Recoveries from spiked samples ranged between 94.5 ± 2.1% and 99.8 ± 1.8%. Graphical abstract A stir foam was prepared from graphene oxide, poly(ethylene glycol) and natural latex (GO-PEG-NL) and is shown to be a most viable sorbent for the microextraction of trace amounts of preservative agents and antioxidants from cosmetic products.

Determination of synthetic phenolic antioxidants in edible oils using microvial insert large volume injection gas-chromatography.

Three synthetic phenolic antioxidants, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and tert-butyl hydroquinone (TBHQ), were determined in different edible vegetable oil samples. The analyses were carried out by gas chromatography-mass spectrometry (GC-MS) using microvial insert large volume injection (LVI). Several parameters affecting this sample introduction step, such as temperatures, times and gas flows, were optimised. Quantification was carried out by the matrix-matched calibration method using carvacrol as internal standard, providing quantification limits between 0.08 and 0.10 ng g(-1), depending on the compound. The three phenolic compounds were detected in several of the samples, BHT being the most frequently found. Recovery assays for oil samples spiked at two concentration levels, 2.5 and 10 ng g(-1), provided recoveries in the 86-115% range.

High-selective and sensitive voltammetric sensor for butylated hydroxyanisole based on AuNPs-PVP-graphene nanocomposites.

Gold nanoparticles (AuNPs) and reduced graphene oxide (graphene) composites were synthesized via a simple one-pot approach in the presence of polyvinylpyrrolidone (PVP). Further, the Au-PVP-graphene nanocomposite was used as a new sensing material for the electrochemical detection of butylated hydroxyanisole (BHA). Because of the greatly enlarged surface area, the enhanced electron transfer rate, and a stronger enrichment of BHA, the sensor based on Au-PVP-graphene modified glassy carbon electrode (GCE) displayed highly sensitive electrochemical responses to BHA. Applying linear sweep voltammetry, a good linear relationship of the oxidation peak current with respect to concentrations of BHA across the range of 0.2-100.0 µM and a detection limit of 0.04 µM was achieved. The practical analytical performance of the Au-PVP-graphene/GCE was examined by evaluating detection of BHA in soybean oil and the flour samples. Satisfactory results revealed that this work offered a new way for the sensitive and simple determination of BHA in complex samples.

Determination of synthetic phenolic antioxidants in soft drinks by stir-bar sorptive extraction coupled to gas chromatography-mass spectrometry.

The synthetic phenolic antioxidants butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and tert-butyl hydroquinone (TBHQ) were pre-concentrated by stir-bar sorptive extraction and thermally desorbed (SBSE-TD) before analysis by GC-MS. Several parameters affecting the derivatisation step and both SBSE extraction and thermal desorption were carefully optimised. When the analyses of BHA and TBHQ in their acetylated, silylated and underivatised forms were compared, the best results were obtained when the in-situ derivatisation procedure with acetic anhydride was employed. Quantification was carried out using carvacrol as the internal standard, providing quantification limits of between 0.11 and 0.15 ng ml(-1), depending on the compound. Recovery assays for samples spiked at two concentration levels, 1 and 5 ng ml(-1), provided recoveries in the 81-117% range. The proposed method was applied in the analysis canned soft drinks and the analytes were found in five of the 10 samples analysed.

Water-contained surfactant-based vortex-assisted microextraction method combined with liquid chromatography for determination of synthetic antioxidants from edible oil.

For the first time, a novel water-contained surfactant-based vortex-assisted microextraction method (WSVAME) was developed for the extraction of two synthetic antioxidants (t-butyl hydroquinone (TBHQ) and butylated hydroxyanisole (BHA)) from edible oil samples. The novel microextraction method is based on the injection of an aqueous solution of non-ionic surfactant, Brij-35, into the oil sample in a conical bottom glass tube to form a cloudy solution. Vortex mixing was applied to accelerate the dispersion process. After extraction and phase separation by centrifugation, the lower sediment phase was directly analyzed by HPLC. The effects of the four experimental parameters including volume and concentration of extraction solvent (aqueous solution of Brij-35), percentage of acetic acid added to the oil sample and vortex time on the extraction efficiency were studied with a full factorial design. The central composite design and multiple linear regression method were applied for the construction of the best polynomial model based on experimental recoveries. The proposed method showed good linearity within the range of 0.200-200 µg mL(-1), the square of correlation coefficient higher than 0.999 and appropriate limit of detection (0.026 and 0.020 µg mL(-1) for TBHQ and BHA, respectively), while the precision for inner-day was ≤ 3.0 (n=5) and it was ≤ 3.80 (n=5) for inter-day assay. Under the optimal condition (30 µL of 0.10 mol L(-1) Brij-35 solution as extraction solvent and vortex time 1 min), the method was successfully applied for determination of TBHQ and BHA in different commercial edible oil samples. The recoveries in all cases were above 95%, with relative standard deviations below 5%. This approach is considered as a simple, sensitive and environmentally friendly method because of biodegradability of the extraction phase and no use of organic solvent in the extraction procedure.

Simple simultaneous determination of butylated hydroquinone (TBHQ) and butylated hydroxyanisole (BHA) antioxidants in oil using high-performance liquid chromatography with chemiluminescence detection.

A highly sensitive and convenient high-performance liquid chromatography technique coupled with chemiluminescence detection for the simultaneous determination butylated hydroquinone (TBHQ) and butylated hydroxyanisole (BHA) in oil is established. The detection is based on the inhibitory effect on the CL reaction between luminol and potassium ferricyanide in an alkaline medium. Samples were separated through a reverse-phase C18 column using a mobile phase of methanol and water (80: 20, v/v) at a flow rate of 0.5 mL/min. The effects of various parameters including mobile phase, flow rate and chemiluminescence regent were studied. Under optimum conditions, both TBHQ and BHA showed good linear relationships in the range 1 × 10(-7) -1 × 10(-5) g/mL with detection limits of 24 and 33 ng/mL, respectively. The proposed method is simple and sensitive, with low costs. The method was successfully applied for the quantification of TBHQ and BHA in sesame oil. The possible inhibition mechanism is also discussed briefly.

[Simultaneous determination of three antioxidants BHA, BHT and TBHQ in food by liquid chromatography and gas chromatography].

OBJECTIVE: To develop a method for determining 3 kinds of antioxidants in food in same time with HPLC and GC. METHODS: Firstly, extracted fat with petroleum ether, then extracted antioxidants with 13 ml methnol, centrifuged, repeated the above procedure twice, combined the extracts, next evaporated to 5 ml, constanted volume to 10 ml, then kepted in freezer (- 1h), lastly, the supernatant injected into high performance liquid chromatography (HPLC) and Gas chromatography (GC) which had been optimized condition. RESULTS: The limits of quantitation for BHA,BHT and TBHQ were 0.002, 0.010 and 0.002g/kg respectively in HPLC, The limits of quantitation for BHA, BHT and TBHQ were 0.003, 0.002 and 0.005 g/kg respectively in GC, The mean recoveries at the two spiked levels were 82.8% - 109.0%. There were no significant difference between HPLC and GC. CONCLUSION: The method can be used to determine the antioxidants in food accurately and sensitively, the comparative results are constant between liquid and gas chromatography.

Glassy carbon electrodes modified with gold nanoparticles for the simultaneous determination of three food antioxidants.

Electrochemical behavior of three antioxidants: butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and butylated hydroquinone (TBHQ), was investigated at a glassy carbon electrode modified with gold nanoparticles (AuNPs/GCE). This electrode was characterized by scanning electron microscopy (SEM). The experimental results indicated that the modified electrode was strongly electroactive during the redox reactions of BHA, BHT and TBHQ, and this was confirmed by the observed increased redox peak currents and shifted potentials; in addition, the oxidation products of BHA and TBHQ were found to be the same. The experimental conditions were optimized and the oxidation peaks of BHA and BHT were clearly separated. Based on this, an electrochemical method was researched and developed for the simultaneous determination of BHA, BHT and TBHQ in mixtures with the use of first derivative voltammetry; the linear concentration ranges were 0.10-1.50 µg mL(-1), 0.20-2.20 µg mL(-1) and 0.20-2.80 µg mL(-1), and detection limits were 0.039, 0.080 and 0.079µgmL(-1), for BHA, BHT and TBHQ, respectively. The proposed method was successfully applied for the analysis of the three analytes in edible oil samples.

New opportunities of the application of natural herb and spice extracts in plant oils: application of electron paramagnetic resonance in examining the oxidative stability.

The aim of this study was to establish the applicability of natural water-ethanol extracts of herbs and spices in increasing the oxidative stability of plant oils and in the production of novel food. Different concentrations (0, 100, 300, 500, and 700 ppm) of spice extracts and butylated hydroxyanisole (BHA) (100 ppm) were added to the studied oils. The antioxidant activity of spice extracts was determined with electron paramagnetic resonance (EPR) spectroscopy using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical assay. The study showed that the extracts significantly increased the oxidative stability of the examined oils when compared to one of the strongest synthetic antioxidants--BHA. The applied simple production technology and addition of herb and spice extracts to plant oils enabled enhancement of their oxidative stability. The extracts are an alternative to the oils aromatized with an addition of fresh herbs, spices, and vegetables because it did not generate additional flavors thus enabling the maintenance of the characteristic ones. Moreover, it will increase the intake of natural substances in human diet, which are known to possess anticarcinogenic properties.

[Determination of antioxidant residues in polymer food package using gas chromatography].

A new method for the determination of antioxidants, butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA) and tertiary butylhydroquinone (TBHQ) in plastic food package by gas chromatography-electron capture detection (ECD) was developed. The antioxidants were extracted by cyclohexane with ultrasonic extraction, separated by an HP-50 + chromatographic column (30 m x 0.53 mm x 1 microm) and quantified by external standard method with an ECD detector. The average recoveries of antioxidants were 88% -93%, 92% - 101% and 83% -97% for BHT, BHA and TBHQ, respectively, at the spiking levels of 3.00 - 10.0 mg/kg. The corresponding relative standard deviations (RSDs, n = 5) were 2.01% - 2.89%, 2.11% - 3.19% and 2.99% - 4.02%, respectively. The limits of detection (S/N = 3) were 0.5, 0.5 and 0.8 mg/kg for BHT, BHA and TBHQ, respectively. The proposed method has been applied to the analysis of 5 kinds of polymer food package. The results indicated that all the above antioxidants were found in the practical polymer food package samples. Plastic food package contained BHT and BHA with the concentrations varying from 6.3 to 7.8 mg/kg and rubber food package contained all the three antioxidants with the concentrations varying from 9.3 to 28.4 mg/kg. This method is accurate, sensitive, highly reproducible and suitable for the analysis of residual antioxidants in polymer food package.

Cloud-point extraction and reversed-phase high-performance liquid chromatography for the determination of synthetic phenolic antioxidants in edible oils.

A cloud-point extraction (CPE) method using Triton X-114 (TX-114) nonionic surfactant was developed for the extraction and preconcentration of propyl gallate (PG), tertiary butyl hydroquinone (TBHQ), butylated hydroxyanisole (BHA), and butylated hydroxytoluene (BHT) from edible oils. The optimum conditions of CPE were 2.5% (v/v) TX-114, 0.5% (w/v) NaCl and 40 min equilibration time at 50 °C. The surfactant-rich phase was then analyzed by reversed-phase high-performance liquid chromatography with ultraviolet detection at 280 nm, using a gradient mobile phase consisting of methanol and 1.5% (v/v) acetic acid. Under the studied conditions, 4 synthetic phenolic antioxidants (SPAs) were successfully separated within 24 min. The limits of detection (LOD) were 1.9 ng mL(-1) for PG, 11 ng mL(-1) for TBHQ, 2.3 ng mL(-1) for BHA, and 5.9 ng mL(-1) for BHT. Recoveries of the SPAs spiked into edible oil were in the range 81% to 88%. The CPE method was shown to be potentially useful for the preconcentration of the target analytes, with a preconcentration factor of 14. Moreover, the method is simple, has high sensitivity, consumes much less solvent than traditional methods, and is environment-friendly. Practical Application: The method established in this article uses less organic solvent to extract SPAs from edible oils; it is simple, highly sensitive and results in no pollution to the environment.

Levels of synthetic antioxidants (ethoxyquin, butylated hydroxytoluene and butylated hydroxyanisole) in fish feed and commercially farmed fish.

Several synthetic antioxidants are authorized for use as feed additives in the European Union. Ethoxyquin (EQ) and butylated hydroxytoluene (BHT) are generally added to fish meal and fish oil, respectively, to limit lipid oxidation. The study was conducted to examine the concentrations of EQ, BHT and butylated hydroxyanisole (BHA) in several commercially important species of farmed fish, namely Atlantic salmon, halibut and cod and rainbow trout, as well as concentrations in fish feed. The highest levels of BHT, EQ and BHA were found in farmed Atlantic salmon fillets, and were 7.60, 0.17 and 0.07 mg kg(-1), respectively. The lowest concentrations of the synthetic antioxidants found were in cod. The concentration of the oxidation product ethoxyquin dimer (EQDM) was more than ten-fold higher than the concentration of parent EQ in Atlantic salmon halibut and rainbow trout, whereas this dimer was not detected in cod fillets. The theoretical consumer exposure to the synthetic antioxidants EQ, BHA and BHT from the consumption of farmed fish was calculated. The contribution of EQ from a single portion (300 g) of skinned fillets of the different species of farmed fish would contribute at most 15% of the acceptable daily intake (ADI) for a 60 kg adult. The consumption of farmed fish would not contribute measurably to the intake of BHA; however, a 300 g portion of farmed Atlantic salmon would contribute up to 75% of the ADI for BHT.