Polycyclic Aromatic Hydrocarbons In Edible Oils Research Articles

Fabrication and application of Zn5 functionalized copolymer monolithic column for pipette tip micro-solid phase extraction of 4 polycyclic aromatic hydrocarbons in edible oil

The contamination of polycyclic aromatic hydrocarbons (PAHs) in edible oil is a health threat. Thus, trace analysis of PAHs is of high necessity. Based on the efficient adsorption of PAHs on Zn5 metal cluster, a Zn5 functionalized copolymer monolithic column was rationally designed for pipette tip micro-solid phase extraction (μ-SPE). The modified Zn5 improved the adsorption selectivity and capacity of the monolith for naphthalene, phenanthrene, fluoranthene and pyrene. Chemical doping and copolymerization stabilized the monolith with a long life. Under optimal extraction conditions, a μ-SPE-high performance liquid chromatography with ultraviolet detector method was established for the detection of 4 PAHs in edible oils. The method yielded detection ranges of 0.15–250 μg L−1 (R2 > 0.997), detection limits of 0.050–1.5 μg L−1, satisfactory recoveries (86.3–101.5 %), and high precisions (RSDs < 7.9 %). The results indicated that the Zn5 functionalized copolymer monolithic column was an ideal separation medium for the detection of PAHs residues in edible oils.

Determination of polycyclic aromatic hydrocarbons in edible oil by magnetic solid phase extraction based on a mesoporous molybdenum disulfide/graphite prior to gas chromatography-mass spectrometry

In this work, a magnetic mesoporous molybdenum disulfide/graphite nanosheets (mm-MoS2/GN) was successfully synthesized and applied to magnetic solid phase extraction (MSPE) of 13 polycyclic aromatic hydrocarbons (PAHs) from edible oil samples. The prepared mm-MoS2/GN was characterized by FT-IR, XRD, VSM, BET, SEM and TEM. The influence of various parameters such as the adsorbent mass, adsorption/desorption time, and elution solvent through response surface methodology in MSPE was investigated. The porous and fluffy structure with rich active sites (π interactions, electrostatics, hydrogen bonds) and amphiphilicity properties of mm-MoS2/GN make it an ideal material for the separation and enrichment of trace PAHs in edible oils. Under optimal MSPE and GC-MS conditions, the linearity ranges of the proposed method were 1.0–100.0 μg·kg−1 with a satisfactory correlation coefficient above 0.9907. The limits of detection and quantification for 13 PAHs were 0.10–2.50 μg·kg−1 and 0.85–5.00 μg·kg−1, respectively. The intra- and inter-day precisions were less than 3.0 % and 3.6 %, respectively. The recoveries for spiked edible oil samples ranged from 70.2 % to 112.6 % with RSDs of less than 5.8 %. In this work, a novel, rapid, economic and effective method was proposed, and successfully applied to detect polycyclic aromatic hydrocarbons in several oil samples from local market.

Monitoring and Occurrence of Heavy PAHs in Pomace Oil Supply Chain Using a Double-Step Solid-Phase Purification and HPLC-FLD Determination.

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental and processing contaminants generated by both spontaneous and anthropogenic incomplete combustion processes of organic matter. Contamination of PAHs in vegetable oils can result from several factors and processes, including environmental contamination, oil processing, and migration from food contact materials. The determination of PAHs in edible oil presents a challenge because of the complexity of the matrix. Since PAHs are present at lower levels than triglycerides, it is necessary to isolate the compounds of interest from the rest of the matrix. To this purpose, a new purification approach based on a double solid-phase extraction (SPE) step followed by high performance liquid chromatography–fluorometric detector (HPLC-FLD) analysis was developed. The method involves a first purification step by using a 5 g silica SPE cartridge, previously washed with dichloromethane (20 mL), dried completely, and then conditioned with n-hexane (20 mL). The triglycerides are retained by the silica, while the PAH-containing fraction is eluted with a mixture of n-hexane/dichloromethane (70/30, v/v). After evaporation, the residue is loaded on a 5 g amino SPE cartridge and eluted with n-hexane/toluene (70/30, v/v) before HPLC-FLD analysis. The focus was the evaluation of the contribution of the various phases of the pomace oil supply chain in terms of the heavy PAHs (PAH8) concentration. Data collected showed that pomace contamination increased (by 15 times) as storage time increased. In addition, the process of pomace drying, which is necessary to reduce its moisture content before solvent extraction of the residual oil, appeared to significantly contribute to the total heavy PAHs content, with increases in value by up to 75 times.

Quality alert from direct discrimination of polycyclic aromatic hydrocarbons in edible oil by liquid-interfacial surface-enhanced Raman spectroscopy

Edible oil is easy to be polluted by polycyclic aromatic hydrocarbons (PAHs) in production, processing, storage and use. Rapid screening of oil quality and safety is a huge demand in food industry and government regulation. Usually, sample pretreatment is needed for PAHs detection due to the complexity of the oil base but greatly limits the detection speed. Here we develop a liquid-interfacial surface-enhanced Raman spectroscopy (SERS) technology without sample pretreatment to realize the rapid and direct detection of ultra-trace PAHs in edible oil within 3 min. A quantitative analysis curve of benzopyrene (BaP) content in soybean oil is established in the range of 0.1 ppb–100 ppm with a high coefficient correlation (R2) of 0.9959 in curve fitting. It was found that only 4.5 h of frying would make the BaP content exceed the limit of 10 ppb in the Chinese Food Safety National Standard. Four common PAHs can be quickly identified in frying oil samples collected from special snack streets and the SERS profiles of soybean oil with adulteration of refined gutter oil could be well classified. This study paves a reliable method to rapid analyze edible oil with broad application prospects in the field of grain and oil safety.

Effervescence-assisted dual microextraction of PAHs in edible oils using lighter-than-water phosphonium-based ionic liquids and switchable hydrophilic/hydrophobic fatty acids.

Herein, we developed a novel effervescence-assisted dual microextraction method, abbreviated as EM-LPSH, using lighter-than-water phosphonium-based ionic liquids (LPILs) and switchable hydrophilic/hydrophobic fatty acids (SHFAs). The EM-LPSH method was utilized for quick enrichment/extraction of polycyclic aromatic hydrocarbons (PAHs) in edible oils. Owing to lower density than water, LPILs used as the first extractant were floated on the upper layer of the aqueous phase, leading to a convenient separation/collection compared with traditional heavier-than-water imidazolium-based ionic liquids. Interestingly, SHFAs play triple functions: a dispersive solvent in the microextraction process, an acidic source in effervescent reaction, and the second extractant in dual microextraction, due to switchability from hydrophilicity to hydrophobicity. Consequently, the integration of LPILs with SHFAs greatly enhanced the extraction efficiency for PAHs owing to the quick dual microextraction process. Some important variables were rigorously optimized using a one-factor-at-a-time approach. Under optimized conditions, the EM-LPSH/HPLC-FLD method provided a wide linear range (0.07~0.63-200μgkg-1), satisfactory recovery (80.12-103.27%), and low limit of detection (0.02-0.19μgkg-1), as well as high intra-day and inter-day precision (0.03-6.55) for six PAHs in edible oils. By using certified reference material in olive oil samples (GBW10162), the recoveries ranged from 97.40 to 98.39%, demonstrating high accuracy and precision. According to the detected levels of PAHs in six unheated and heated oils, their edible safety was evaluated in detail. In short, the newly developed method is simple, convenient, and highly efficient, thereby showing great prospects for application in conventional monitoring of trace-level PAHs in edible oils.

On-site separation and identification of polycyclic aromatic hydrocarbons from edible oil by TLC-SERS on diatomite photonic biosilica plate

The accumulated polycyclic aromatic hydrocarbons (PAHs) in edible oil can bring serious health concerns because of their carcinogenic features. PAHs could accumulate in edible oil from contaminated environment or food stuff. In this study, the combination uses of on-site thin layer chromatography and surface enhanced Raman scattering (SERS) spectroscopy has been successfully displayed to identify PAHs from edible oil samples. Diatomite which is a kind of porous biosilica was used to construct stationary phase on TLC plate, the photonic crystal feature of diatomite is beneficial for SERS enhancement. The highly-porous stationary phase composed of porous diatomite with void shell structure could promote mobile phase interaction with the stationary phase, which leading to improved mass transfer, uniformity and analyte resolution compare with the conventional silica gel plate. The edible oil (1 µL) was directly applied to the diatomite plate without pretreatment, and subjected to TLC separation. The polarity of target analytes was calculated for eluent optimization, on which four compounds of PAHs(benzo[a]pyrene, pyrene, anthracene and indeno[1,2,3-cd] pyrene) were successfully separated by using hexane/chloroform (15/1, v/v) as eluent, including compounds with similar polarity(benzo[a]pyrene 0.0477, indeno[1,2,3-cd] pyrene 0.6545, pyrene and anthracene are 0). 2 µL of Au colloid at 2.4 × 10−7 M were transferred onto the diatomite plate for the SERS measurement. The limit of detection was found to be nearly at 1 ppm. The obtained results can easily identify the four compounds of PAHs in edible oil by their own characteristic Raman peaks. This proposed method provides a simple, instant and effective strategy for on-site identification PAHs from food samples.

The effects of extracting procedures on occurrence of polycyclic aromatic hydrocarbons in edible oils.

Polycyclic aromatic hydrocarbons (PAHs) are one of the most hazardous naturally occurring chemical contaminants of food. Edible oils are easily contaminated by PAHs generated during high-temperature processing steps such as oil extraction and refining. In this study, the effects of different extraction methods on the levels of PAHs in sesame oils and red pepper seed oils were assessed. GC-MS was used to determine the levels of PAHs in edible oils. Sesame oils extracted from seeds by plate-pressing extraction method had lower levels of PAHs than those extracted by screw-expeller extraction method from sesame flour. Furthermore, the levels of PAHs increased by 62.2% when the extraction time was longer. Notably, the PAHs already present in oils could be effectively reduced by refining procedures such as sinking, centrifugation, filtration, and neutralization with alkali.

Incidence and survey of polycyclic aromatic hydrocarbons in edible vegetable oils in China

Polycyclic aromatic hydrocarbons (PAHs) occurrence in eighty-five samples of edible vegetable oils from China was described for the first time. Analytes were determined based on a simplified solvent extraction and liquid chromatography-atmospheric pressure photoionization-tandem mass spectrometry method. PAHs were detected in all of the oil samples and the concentrations of BaP, PAH4 and PAH16 were 0.12–6.28, 1.48–27.84 and 9.25–154.27 μg/kg, respectively. Levels of BaP were all conformed to the upper limit 10 μg/kg set by China. However, each had 13% of oil samples (11 samples) exceeded the maximum limit 2 and 10 μg/kg set for BaP and PAH4 by EU. The light PAHs were primary in oil samples, and the contribution of the heavy PAHs was much less significant. A high variability of PAH levels between different oil types was observed, and peanut oils and sesame oils were two types of oils that were highly contaminated. The relationship between BaP and PAH4, BaP and PAH16 and PAH4 and PAH16 suggested that PAH4 was more suitable than BaP acted as a surrogate for the contamination level of PAHs in edible oils.

Simultaneous determination of 24 polycyclic aromatic hydrocarbons in edible oil by tandem solid-phase extraction and gas chromatography coupled/tandem mass spectrometry.

An efficient and fast tandem SPE method followed by GC/MS/MS has been developed for the determination and the quantification of 24 polycyclic aromatic hydrocarbons (PAHs) in edible oil. This method includes the monitoring of 15 + 1 PAHs designated as a priority by the European Union in their 2005/108/EC recommendation and 16 PAHs listed by the U. S. Environmental Protection Agency. The sample preparation procedures were based on SPE in which PAH-dedicated cartridges with molecularly imprinted polymers and graphitized carbon black were used in series. The novel tandem SPE combination of selective extraction and purification of light and heavy PAHs provided highly purified analytes. Identification and quantification of 24 target PAHs were performed using GC/MS/MS with the isotope dilution approaches using D-labeled and (13)C-labeled PAHs. The advantages of GC/MS/MS as compared to other detection methods include high sensitivity, selectivity, and interpretation ability. The method showed satisfactory linearity (R(2) > 0.998) over the range assayed (0.5-200 μg/kg); the LODs ranged from 0.03 to 0.6 μg/kg, and LOQs from 0.1 to 2.0 μg/kg. The recoveries using this method at three spiked concentration levels (2, 10, and 50 μg/kg) ranged from 56.8 to 117.7%. The RSD was lower than 12.7% in all cases. The proposed analytical method has been successfully applied for the analysis of the 24 PAHs in edible oil.

Screening of edible oils for polycyclic aromatic hydrocarbons using microwave-assisted liquid–liquid and solid phase extraction coupled to one- to three-way fluorescence spectroscopy analysis

The potential of microwave-assisted liquid–liquid and solid phase extraction coupled with fluorescence spectroscopy and employing one- to three-way spectral data was assessed in terms of their capacity for the rapid detection of heavy polycyclic aromatic hydrocarbons (PAHs) in olive and sunflower oils. Tocopherols and pigments groups (chlorophyll and pheophytin) present in oil matrices were the main interference compounds in the detection of PAHs using fluorescence spectroscopy. Partial spectral overlap and inner-filter effects were observed in the emission range of the analytes. The effectiveness of removing these interferences using solid phase extraction (silica, C18 and graphitized carbon black) was examined. Solid phase extraction with silica was the most effective method for the removal of pigments and tocopherol and allowed for the detection of PAHs in edible oils using fluorescence spectroscopy. The limit of detection was observed to depend on the use of one-, two- or three-way fluorescence spectral data in the range of 0.8 to 7.0μgkg−1. The individual recoveries of PAHs following the microwave-assisted L–L extraction and SPE with silica were assessed using HPLC–FD with satisfactory results.

Single laboratory validation of a SPE method for the determination of PAHs in edible oils by GC-MS

This article describes a method for the quantification of seven Polycyclic Aromatic Hydrocarbons (PAHs) in edible oils (soy, sunflower and olive). It involved the application of a low-volume liquid–liquid extraction (LLE) technique followed by a solid-phase extraction (SPE) clean-up with C18 and silica cartridges. Separation and analysis of compounds were performed by gas chromatography coupled to mass spectrometry (GC-MS). 13C-labeled PAHs as internal standards were used to aid the identification of compounds and to determine the efficiency of the extraction method in an isotope dilution mass spectrometry (IDMS) approach. Low-volume LLE and SPE clean-up procedures allowed the reduction of solvent consumption, eliminated the necessity of a previous saponification step and provided less sample preparation time when compared to traditional PAHs extraction and clean-up methods. The analytical procedure was validated according to recommendations of the European Commission Decision 2002/657/EC and European Commission Regulations (2007/333/EC and 2011/836/EU). Acceptable values (except for chrysene) were obtained for the following parameters: linearity (r2 > 0.98), limit of quantification (0.12 < LOQ < 0.68 μg kg−1), limit of detection (0.04 < LOD < 0.23 μg kg−1), trueness (recovery rates and certified reference material normalized error), and precision (repeatability and intermediate precision). Recoveries higher than 80% were attained for seven PAHs, at three concentration levels (0.75, 2.00 and 4.00 μg kg−1). This validated method will be used by the Ministry of Agriculture, Livestock and Food Supply in Brazil.

Rapid Magnetic Solid-Phase Extraction Based on Magnetic Multiwalled Carbon Nanotubes for the Determination of Polycyclic Aromatic Hydrocarbons in Edible Oils

In this study, magnetic multiwalled carbon nanotubes were fabricated by a simple method and applied to magnetic solid-phase extraction (MSPE) of eight heavy molecular weight polycyclic aromatic hydrocarbons (PAHs) including chrysene, benzo[a]anthracene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, indeno[1,2,3-cd]pyrene, dibenzo[a,h]anthracene and benzo[g,h,i]perylene from edible oil samples. Several parameters affecting the extraction efficiency were investigated, including the type and volume of desorption solvent, extraction and desorption time, washing solution and the amount of sorbent. Under the optimized conditions, a simple and effective method for the determination of PAHs in edible oils was developed by coupling with gas chromatography-mass spectrometry (GC-MS). The whole pretreatment process was rapid, and it can be accomplished within 10 min. The limits of quantitation for the target PAHs were found to be 0.34-2.9 ng/g. The recoveries in oil sample were in the range 87.8-122.3% with the RSDs less than 6.8% (intraday) and 9.6% (interday). This method was successfully applied to the analysis of PAHs in seven kinds of edible oils from local markets.

Development and optimisation of a dopant assisted liquid chromatographic-atmospheric pressure photo ionisation-tandem mass spectrometric method for the determination of 15 + 1 EU priority PAHs in edible oils

European food legislation defines a set of 16 polycyclic aromatic hydrocarbons (PAHs) as of high concern for human health. The EU set contains structurally very similar PAHs with ring numbers between 4 and 6, and so raises some separation aspects and problems, which were not experienced with traditionally analysed PAHs. Many of the currently applied gas chromatographic mass spectrometric (GC–MS) methods suffer from separation problems, while high performance liquid chromatography with fluorescence detection (HPLC-FLD) is neither capable of detecting the whole set of EU priority PAHs nor does it (compared to GC–MS) allow structural identification. In addition HPLC-FLD shows limitations with difficult matrices due to interferences. The aim of this paper is to fill this gap by describing a liquid chromatographic dopant assisted atmospheric pressure photo ionisation tandem mass spectrometric (LC-DA-APPI-MS/MS) method for the determination of 15+1 EU priority PAHs in edible oil, which complies with the requirements set by European food legislation. Measurements were performed in positive ion mode. Anisole at a flow rate of 30μl/min was used as dopant. Sample preparation was performed offline by donor–acceptor complex chromatography (DACC). Compared to HPLC-FLD methods the presented method enables the determination of all 15+1 EU priority PAHs at the low μg/kg concentration range including less fluorescence active compounds like benzo[j]fluoranthene and indeno[1,2,3-cd]pyrene. By analysing four reference materials it could be demonstrated that this method provides accurate results and is sufficiently sensitive for food control purposes. Statistically significant differences between the reference values and the measured analyte contents were not found. The method performs well also for very complex samples. Repeatability relative standard deviations (RSDr) of the determination of the target PAHs in olive oil were for most analytes below 5%. The limit of detection (LOD) of the method met the requirement set by EU legislation (0.3μg/kg).