Ultrasonication extraction and gel permeation chromatography clean-up for the determination of polycyclic aromatic hydrocarbons in edible oil by an isotope dilution gas chromatography–mass spectrometry

Recent Advances in Sample Preparation and Chromatographic/Mass Spectrometric Techniques for Detecting Polycyclic Aromatic Hydrocarbons in Edible Oils: 2010 to Present

Polycyclic aromatic hydrocarbons are considered to be potentially genotoxic and carcinogenic to humans. For non-smoking populations, food is the main source of polycyclic aromatic hydrocarbons exposure. Due to their lipophilic nature, oils and fats rank among the food items with the highest polycyclic aromatic hydrocarbon content. Consequently, the detection of polycyclic aromatic hydrocarbons in edible oils is critical for the promotion of human health. This paper reviews sample pretreatment methods, such as liquid-phase-based extraction methods, adsorbent-based extraction methods, and the QuEChERS (quick, easy, cheap, effective, rugged, and safe) method, combined with detection techniques like mass spectrometry and chromatography-based techniques for accurate quantification of polycyclic aromatic hydrocarbons in edible oils since 2010. An overview on the advances of the methods discussed herein, along with a commentary addition of current challenges and prospects, will guide researchers to focus on developing more effective detection methods and control measures to reduce the potential risks and hazards posed by polycyclic aromatic hydrocarbons.

Rapid Screening of 22 Polycyclic Aromatic Hydrocarbons Residues in Vegetable Oils by Gas Chromatography-Electrostatic Field Orbitrap High Resolution Mass Spectrometry

A method for simultaneous determination of 22 polycyclic aromatic hydrocarbons (PAHs) residues in vegetable oils by gas chromatography-electrostatic field orbitrap high resolution mass spectrometry (Orbitrap GC-MS) was established. The samples were vortexed with acetonitrile, centrifuged at 8,000 r/min for 5 min, and frozen at −70°C for 10 min. The extracts of upper layer were poured out, dried with nitrogen at 40°C, redissolved in dichloromethane, and measured by Orbitrap GC-MS. The matrix interference in vegetable oil could be effectively removed by determining the accurate mass number of target compounds under the full scan mode. Six typical vegetable oil samples (soybean oil, sesame oil, peanut oil, olive oil, rapeseed oil, sunflower oil) were used for method validation. The calibration curve displayed good linearity in the range of 1–100 ng/mL, with correlation coefficients > 0.9950. The limits of detection (LODs) were in the range of 0.10–0.60 μg/kg, and the limits of quantification (LOQs) were in the range of 0.35–2.00 μg/kg. The average spiked recoveries of 22 PAHs in 6 matrices at 5, 50 and 100 μg/kg levels were 76.4–115.4%, and the average relative standard deviations (RSDs) were 1.8–10.8%. The results showed that 22 PAHs were detected in 6 types of 90 edible vegetable oil samples in the Chinese market by this method. Meanwhile, the abundance of light PAHs (LPAHs) was higher than that of heavy PAHs (HPAHs), and its relative contribution of LPAHs to the total PAHs was higher. All levels of BaP conformed to the Chinese requirement of upper limit, 10 μg/kg. However, 13.3 and 11.1% of the samples exceeded the maximum limits of BaP and PAH4 set by EU, 2 and 10 μg/kg, respectively. The total concentrations of 22 PAHs (defined as PAH22) varies greatly among different oil species, and the average PAH22 contents were listed in descending order as follows: peanut oil > sesame oil > olive oil > rapeseed oil > soybean oil > sunflower seed oil. The established method effectively avoided interference from large amounts of lipids and pigments. Therefore, the method is simple, sensitive and suitable for rapid screening and confirmation of PAHs in vegetable oil.

Advanced Gel Permeation Chromatography system with increased loading capacity: Polycyclic aromatic hydrocarbons detection in olive oil as a case of study

Gel permeation chromatography (GPC) is herein used as size exclusion clean-up technique for highly sensitive and straightforward detection of Polycyclic Aromatic Hydrocarbons (PAHs) in olive oil samples. An advanced chromatographic system has been developed to isolate a series of PAHs with cancerogenic potential, including PAH4 (benzo(a)pyrene BaP, benzo(a)anthracene BaA, benzo(b)fluoranthene BbF and chrysene Chry) reported in the European Regulation. The system avails of two glass chromatographic columns and a switching valve, that allow removal of interfering analytes in olive oil without resorting to any preliminary extraction process. A seven-fold increase of the loaded sample amount versus conventional chromatographic systems (1 g vs 0.150 g) has been pursued, as well as improved PAHs detection and quantification limits (LOD-LOQ for PAH4: 0.21-0.70 ng/g for BaA, 0.26-0.86 ng/g for Chry, 0.23-0.76 ng/g for BbF, 0.32-1.06 ng/g for BaP), in accordance with the continuous need of more and more reducing these limits in food analysis by the European Regulation. The protocol developed represents a highly innovative and efficient analytical method for organic pollutants in complex biological matrices as olive oil, that can have huge impact on technology for PAHs detection in food samples, being suitable for both industrial and small-scale laboratories.

Determination of polycyclic aromatic hydrocarbons in olives exposed to three different industrial sources and in their respective oils

Atmospheric contamination of plant raw material with Polycyclic Aromatic Hydrocarbons (PAHs) helps explain their presence in edible vegetable oils. This study compared PAH contamination of Turkish olive fruits during their growing period on the tree and their respective oils from three different industrial sources (petroleum refinery, thermal power plant and heavy industry site). The method included liquid-liquid extraction solid-phase extraction for cleanup followed by HPLC with fluorescence detector. There were statistically significant differences between the three industrial sources in benzo[a]pyrene content, the sum of light, total PAHs and PAH4 (p˂0.05), but only slight differences in PAH profiles. The highest level of PAH compounds was measured in samples exposed to pollution from the petroleum refinery, nearly twice as high as samples exposed to the thermal power plant which showed the lowest contamination levels. None of the samples analysed exceeded the limits stipulated by current legislation. The transfer ratios of PAH compounds from olives to olive oil were 22.8-73.2%. This indicates that PAHs either diffuse directly from skin to oil within the fruit or transfer during oil extraction.

Detection, Risk Assessment, and Survey of Four Polycyclic Aromatic Hydrocarbon Markers in Infant Formula Powder

A gas chromatography-mass spectroscopy (GC-MS) method was developed to assess the infant exposure assessment from four important polycyclic aromatic hydrocarbon (PAH) markers in infant formula powder: benzo[a]anthracene, chrysene, benzo[b]fluoranthene, and benzo[a]pyrene (collectively referred to as PAH4). The developed method required the addition of an isotopically labeled internal standard, sample extraction under alkali conditions, a saponification step, and a solid-phase extraction purification step. In a controlled spike test, the average recovery rates of PAH4 were 77.3% to 111.8% and the relative standard deviations were 4.8% to 14.2% (n = 6). The quantitative limit (LOQ) and detection limit (LOD) of the method were 0.5 and 0.1 μg·kg−1, respectively. The PAH4 content was analyzed in 30 commercially available infant formula powders. The PAH4 content was found to be in the range of 0.1 to 0.87 μg·kg−1. Combined with the daily intake of infant milk powder in China, the average and maximum daily exposure of BaP for stage-1 infants in China are 0.45 ng/kg.bw.d−1 and 1.9 ng/kg.bw.d−1 and the PAH4 values are 8.6 ng/kg.bw.d−1 and 18.6 ng/kg.bw.d−1, respectively. The PAH4 content in the tested infant formula powders sold in the China were sufficiently low, and all of the tested products were safe for consumption.

Quantification of Cl-PAHs and their parent compounds in fish by improved ASE method and stable isotope dilution GC-MS

This study aimed at developing a simple and accurate method for determination of emerging chlorinated polycyclic aromatic hydrocarbons (Cl-PAHs) in fish by stable isotope dilution gas chromatography tandem mass spectrometry. Fish samples were extracted by improved accelerated solvent extraction (ASE) method. Matrix effects were observed, and matrix-matched calibration was verified with good intra-day and inter day precisions (lower than 16.1% and 15.1% respectively). Method detection limits were 0.10-5.62 ng g^-1 (dry weight) with satisfactory linearity, and recoveries ranged from 50% to 150%, with relative standard deviation values less than 18.5% at different concentration levels. This improved ASE method was proved to be suitable for analyzing Cl-PAHs in fish samples, with good analytical selectivity, linearity, recovery and precision. Furthermore, the composition analysis revealed that chlorinated compounds of phenanthrene, pyrene and acenaphthene were dominated in Cl-PAHs contaminants. The correlationship between the pollution of Cl-PAHs and their corresponding parent structures in fish samples was also analyzed in detail.

Biological and analytical techniques used for detection of polyaromatic hydrocarbons

Polycyclic aromatic hydrocarbons contain two or more fused benzene rings that are considered as cosmo-pollutants ubiquitously found in the environment. The identification and monitoring of polycyclic aromatic hydrocarbons (PAHs) are of great interests for rapid and on-site detection. Therefore, many analytical and biological techniques have been proposed for the qualitative and quantitative assessments of PAHs. Non-biological analytical techniques such as infrared, Raman, and fluorescence spectroscopies are commonly exploited as non-destructive techniques while gas chromatography (GC) and high-performance liquid chromatography (HPLC) with multiple detectors are extensively employed for the separation and detection of an analyte. Even though spectroscopy and chromatography are more accurate, convenient, and feasible techniques, often, these methods are expensive and sophisticated which require high maintenance cost. On the other hand, biological approaches, i.e., immunoassay, PCR, and microarray, offer comprehensive high-throughput specificity and sensitivity for a similar analyte. Biosensor- and immunoassay-mediated detections of PAHs have opened up new avenues in terms of low cost, rapid determination, and higher sensitivity. In this review, we have discussed the strengths and limitations of biological and analytical techniques that were explored for precise evaluation and were trusted at both the legislation and research levels.

Accelerated solvent extraction method for the quantification of polycyclic aromatic hydrocarbons in cocoa beans by gas chromatography-mass spectrometry

An accelerated solvent extraction (ASE) procedure for use with gas chromatography-mass spectrometry (GC-MS) was optimized for the determination of eight polycyclic aromatic hydrocarbons (PAHs) in cocoa beans. Plackett-Burman and rotatable central composite design (RCCD) indicated that three variables affected the recoveries of PAHs during the extraction and purification steps: agitation time in the second liquid-liquid partition, weight of silica gel in the column, and volume of hexane for PAH elution from the column. After obtaining the optimal conditions, a single laboratory method validation was performed. Linearity was demonstrated for benzo[a]pyrene in the concentration range from 0.5 to 8.0mgkg^-1 of sample, corresponding to 1.25-20.0μgkg^-1 of cocoa on a fat basis. For the other analytes, linearity was observed from 0.75 to 8.0μgkg^-1 of sample (1.88-20.0μgkg^-1 of cocoa on a fat basis). Significant matrix effects were found for chrysene and benzo[b]fluoranthene. The precision of the method was verified with relative standard deviations (RSDs) ranging from 2.57 to 14.13% and from 4.36 to 19.77% under repeatability and intermediate precision conditions, respectively. The average recoveries of the eight PAHs ranged from 74.99 to 109.73%. These parameters, limits and measurement uncertainties met the performance criteria established by European Union regulations, except for the theoretical limit of detection for chrysene. The method was applied to the analysis of samples of Brazilian cocoa beans, and only one sample was found to have a PAH content above the maximum limit defined by the European Union legislation. This optimized and validated method is intended to be used as part of the official Brazilian monitoring programs investigating contaminants and residues in food.

Optimized Multiresidue Analysis of Organic Contaminants of Priority Concern in a Daily Consumed Fish (Grass Carp)

The organic contaminants, including polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs), polybrominated diphenyl ethers (PBDEs), and polychlorinated biphenyls (PCBs), are of priority concern because of their persistence, toxicity, and long-distance transportation in global environment. Their residues in a daily consumed fish (grass carp) pose potential threat to human health and aquatic ecosystems. The present study optimized an analytical protocol of microwave-assisted extraction (MAE), lip-removal by gel permeation chromatography (GPC), cleanup by solid phase cartridge (SC) or adsorption chromatography column (CC), and gas chromatography-mass spectrometry (GC/MS). Besides traditional statistical parameters, some indicators were calculated to judge the performances of extraction by various methods. The optimization experiment showed that n-hexane/acetone was the best MEA extraction solvent; an optimal fraction time of 10-39 min could simultaneously elute all the target chemicals in a single GPC run. Both CC and SC showed good recoveries. However, CC performed better than SC (p < 0.05) for OCPs, and SC performed better than CC for PBDEs (p < 0.05). We also emphasized the limitations and advantages of SC and CC and finally proposed SC as the promising cleanup method because of its low-cost materials, time-saving steps, being free of manual filling, and operation by automated SPE system.

A Critical Review about the Health Risk Assessment of PAHs and Their Metabolites in Foods

Polycyclic aromatic hydrocarbons (PAHs) are a family of toxicants that are ubiquitous in the environment. These contaminants generate considerable interest, because some of them are highly carcinogenic in laboratory animals and have been implicated in breast, lung, and colon cancers in humans. Dietary intake of PAHs constitutes a major source of exposure in humans. Factors affecting the accumulation of PAHs in the diet, their absorption following ingestion, and strategies to assess risk from exposure to these hydrocarbons following ingestion have received very little attention. This review, therefore, focuses on concentrations of PAHs in widely consumed dietary ingredients along with gastrointestinal absorption rates in humans. Metabolism and bioavailability of PAHs in animal models and the processes, which influence the disposition of these chemicals, are discussed. Finally, based on intake, disposition, and tumorigenesis data, the exposure risk to PAHs from diet is presented. This information is expected to provide a framework for refinements in risk assessment of PAHs.

Determination of volatile organic and polycyclic aromatic hydrocarbons in crude oil with efficient gas-chromatographic methods

Determination of volatile organic compounds (VOCs) in crude oil, such as super volatile organic compounds (super VOCs) and simple polycyclic aromatic hydrocarbons (PAHs), is vital for targeting crude oil spill spots. In this study, a static headspace gas chromatography flame ionization detection method was established for determination of super VOCs in crude oil with both external and internal standard determination, which can be used in the field when using portable gas chromatography. Identification was done by comparing the retention time with the corresponding standards and quantitation was done with a new one-drop method. Another simplified and efficient method was performed to analyze volatile PAHs in crude oil, which can also be used in field analysis. Toluene was used as the extraction solvent for PAHs in crude oil. Method validation for both analyses was satisfactory. The result showed that n-butane and n-pentane were maximum super VOCs and naphthalene, phenanthrene and fluorene were the main PAHs in the crude oil studied. The super VOCs quantity ranged from 3 to 6% and the main PAHs consisted of 0.02-0.06% of studied crude oil.

Simultaneous analysis of phthalates, adipate and polycyclic aromatic hydrocarbons in edible oils using isotope dilution-gas chromatography-mass spectrometry

A method for simultaneous determination of 12 priority phthalates, adipate and polycyclic aromatic hydrocarbons (PAHs) in edible oils by isotope dilution-gas chromatography-mass spectrometry (ID-GC-MS) was developed for fast, accurate and trace analysis. The extraction and clean-up procedures were optimised, and using stable isotope-labelled internal standards for each analyte, relative standard deviations (RSDs) of 0.92-10.6% and spiked sample recoveries of 80.6-97.8% were obtained. Limits of detection for PAHs were in the range of 0.15-0.77 µg/kg and those for phthalates were in the range of 4.6-10.0 µg/kg. The calibration curves exhibited good linearities with regression coefficients of R(2) ≥ 0.99. Twelve edible oils were examined to evaluate the efficiency of this method. Among the 12 analytes, dibutyl phthalates (DBP), diethylhexyl phthalates (DEHP), diethylhexyl adipate (DEHA), benzo[a]anthracene (B[a]A), chrysene (Chry) and benzo[b]fluoranthene (B[b]F) were detected in the range of 1.17-806 µg/kg.

Use of gel permeation chromatography for clean-up in the analysis of coccidiostats in eggs by liquid chromatography-tandem mass spectrometry

An analytical method for determination and confirmation of nine coccidiostatics in eggs is reported. Ethyl acetate is used as extraction solvent, with satisfactory results, and simple automated clean-up is based on gel-permeation chromatography (GPC) . The target compounds are then analysed by liquid chromatography-electrospray ionization-tandem mass spectrometry. The method was validated in-house in accordance with Commission Decision 2002/657/EC. Trueness and precision were determined at four concentrations, and the mean errors obtained were <10 %, with relative standard deviations ranging from 3 to 18 %. For three non-authorized coccidiostatics (clopidol, ethopabate, and ronizadole), decision limit and detection capability were in the ranges 0.12-0.16 and 0.18-0.23 μg kg(-1), respectively. The results obtained prove the suitability of this new analytical method for routine monitoring of these substances in eggs.

Determination of a risk management primer at petroleum-contaminated sites: developing new human health risk assessment strategy

Total petroleum hydrocarbon (TPH) is an important environmental contaminant that is toxic to human and environmental receptors. However, human health risk assessment for petroleum, oil, and lubricant (POL)-contaminated sites is especially challenging because TPH is not a single compound, but rather a mixture of numerous substances. To address this concern, this study recommends a new human health risk assessment strategy for POL-contaminated sites. The strategy is based on a newly modified TPH fractionation method and includes an improved analytical protocol. The proposed TPH fractionation method is composed of ten fractions (e.g., aliphatic and aromatic EC8-10, EC10-12, EC12-16, EC16-22 and EC22-40). Physicochemical properties and toxicity values of each fraction were newly defined in this study. The stepwise ultrasonication-based analytical process was established to measure TPH fractions. Analytical results were compared with those from the TPH Criteria Working Group (TPHCWG) Direct Method. Better analytical efficiencies in TPH, aliphatic, and aromatic fractions were achieved when contaminated soil samples were analyzed with the new analytical protocol. Finally, a human health risk assessment was performed based on the developed tiered risk assessment framework. Results showed that a detailed quantitative risk assessment should be conducted to determine scientifically and economically appropriate cleanup target levels, although the phase II process is useful for determining the potency of human health risks posed by POL-contamination.