Determination of phthalate sum in fatty food by gas chromatography

A Review of the Analysis of Phthalates by Gas Chromatography in Aqueous and Food Matrices

As a commonly well-known industrial chemical, phthalates are produced in high volumes to be used in various consumer products (e.g., plasticizers, medical devices, construction materials, and toys) to enhance softness, durability, transparency, and flexibility. Phthalates are generally not chemically bonded to the polymer chain of the plastic in which they are mixed. Thus, they may leach, migrate, or evaporate into indoor/outdoor air, and foodstuffs. In this review, a comprehensive overview of several sample preparation methods coupled with gas chromatography for the analysis of phthalates in various kinds of complex matrices, with a focus on the last 20 years' worth of papers. The review begins by highlighting the environmental significance of phthalate pollution along with the various routes to their exposure to general population. Then, the discussion is extended to cover the pretreatment and extraction techniques for phthalates for their quantitation based on gas chromatographic approach. Finally, the present and future challenges for the detection of phthalates in aqueous and food matrices are discussed.

Preparation of SERS substrate with 2D silver plate and nano silver sol for plasticizer detection in edible oil

As a widely used industrial additive of plastic products, phthalate ester (PAE) plasticizers can easily migrate into food, threatening human health. In this work, we proposed a rapid, precise, and reliable method to detect PAE plasticizers in edible oils by using surface-enhanced Raman spectroscopy (SERS) technology. A two-dimensional (2D) silver plate synergizing with a nanosilver sol was prepared as a substrate for SERS to detect potassium hydrogen phthalate (PHP), a hydrolysate of a PAE plasticizer. Detection conditions, such as pH values, drying times, and hydrolysate interference, were optimized. The working curve was well fitted with a linear parameter R² of 0.9994, and the minimum detection limit was evaluated as 10^-9 mol/L. Furthermore, the detection accuracy was supported by five edible oil samples. Therefore, using SERS technology to detect PHP is expected to provide an avenue for PAE plasticizer detection in oils and fats, and it features promising potential applications in food safety.

Methods for the analysis of endocrine disrupting chemicals in selected environmental matrixes

Endocrine disrupting chemicals (EDCs) are heterogenous in structure, chemical and physical properties, and their capacity to partition into various environmental matrixes. In many cases, these chemicals can disrupt the endocrine systems of vertebrate and invertebrate organisms when present at very low concentrations. Therefore, sensitive and varied analytical methods are required to detect these compounds in the environment. This review summarizes the analytical methods and instruments that are most used to monitor for EDCs in selected environmental matrixes. Only those matrixes for which there is a clear link between exposures and endocrine effects are included in this review. Also discussed are emerging methods for sample preparation and advanced analytical instruments that provide greater selectivity and sensitivity.

Occurrence and exposure risk assessment of phthalate esters in edible plant oils with a high-frequency import rate in west China

Phthalate esters (PAEs) are ubiquitous pollutants in the environment with toxicological and epidemiological effects for humans. As one of the daily necessities, edible plant oil is an important exposure source of PAEs, due to the inevitable contact with PAE-containing materials and the intrinsic lipid solubility of PAEs. However, limited information is currently available on the exposure risk of PAEs in commercial plant oil. This study was aimed at investigating the occurrence and risk assessment of PAEs in plant oils with a high-frequency import rate in west China. The analysis method was referenced to the Chinese national standard for the determination of PAEs in food. Results indicated that PAEs (mainly including DBP and DEHP) were ubiquitous contaminants in imported plant oils with the detectable rate being up to 56.83% in 366 samples. The detected concentrations were in the range of 0.10-3.20 mg kg-1 (median 0.28 mg kg-1) for dibutyl phthalate (DBP) and 0.25-1.95 mg kg-1 (median 0.44 mg kg-1) for bis(2-ethylhexyl)phthalate (DEHP). Based on an integrated probabilistic analysis method, the values of non-carcinogenic risk were lower than 1 in all cases, indicating that there would be an unlikely incremental non-carcinogenic risk to humans. Generally, the carcinogenic risk of DEHP was lower than the upper acceptable carcinogenic risk level (<10-4), while 50.40% of the carcinogenic risk exceeded the lower acceptable carcinogenic risk level (>10-6). Besides, diverse health risks were obviously shown and discussed for different categories of plant oils. The obtained results in this study could provide valuable information to understand the contamination status and health risk of PAEs in plant oil and improve the relative supervision and regulation. And the proposed strategy suggests a potential application for health risk assessment of other contaminants in food or even environments.

Establishment and Validation of a GC-MS/MS Method for the Quantification of Penicillin G Residues in Poultry Eggs

A simple and sensitive gas chromatography-tandem mass spectrometry (GC-MS/MS) method was established for the quantitative screening of penicillin G residues in chicken and duck eggs (whole egg, yolk and albumen). The analyte was separated on a TG-1MS capillary column (30.0 m × 0.25 mm i.d., 0.25 μm) with an external calibration method and electron impact (EI) ionization. Samples were pretreated using an accelerated solvent extraction (ASE) procedure followed by solid-phase extraction (SPE) on HLB cartridges (60 mg/3 mL). The derivative, which was safer and easier to store than penicillin G, was obtained by reacting trimethylsilyl diazomethane (TMSD) with penicillin G. The method was validated by the following parameters: linearity, accuracy, precision, limit of detection (LOD) and limit of quantification (LOQ). The matrix-matched calibration curves had good linearity (R2 ≥ 0.9994) within the concentration range of LOQ-200.0 µg/kg for penicillin G in the sample matrices. In the same concentration range, the accuracy, in terms of recovery, was 80.31-94.50%; the relative standard deviation (RSD), intra-day RSD and inter-day RSD ranged from 1.24 to 3.44%, 2.13 to 4.82% and 2.74 to 6.13%, respectively. The LODs and LOQs of penicillin G in the matrices were in the ranges of 1.70-3.20 and 6.10-8.50 μg/kg, respectively. The applicability of the GC-MS/MS method was demonstrated by the determination of poultry eggs obtained from local markets with no penicillin G residues.

Rapid recognition of di-n-butyl phthalate in food samples with a near infrared fluorescence imprinted sensor based on zeolite imidazolate framework-67

Di-n-butyl phthalate (DBP) as a plasticizer is widely used in food and chemical industries. It is harm to human health when it appeared in food and water. A novel near-infrared (NIR) fluorescence molecularly imprinted sensor based on CdTe quantum dots and zeolite imidazolate framework-67 was developed with a sol-gel polymerization method for rapid and sensitive determination of DBP in foodstuff rapidly (only in 1.5 min). The fluorescence imprinted sensor provided a rapid detection method for DBP in the linear response concentration range of 0.05-18.0 μM with a low detection limit of 1.6 nM. Compared with previous fluorescence imprinted sensor, it behaved faster response speed and lower detection limit for determination of DBP. The fluorescence imprinted sensor was used to detect DBP in real samples successfully with satisfied recoveries of 97.2-106.4%, suggesting a potential application in food analysis.

A highly sensitive and group-targeting aptasensor for total phthalate determination in the environment

As the most widely used and typical kind of plasticizers, phthalate esters (PAEs) have become one of the most common environmental pollutants in the world. Therefore, it is necessary to develop a rapid and convenient method for determining the total amount of PAEs. Herein, a molecularly tailored broad-spectrum aptamer that can recognize multiple similarly structured total amounts of PAEs (TP) and bind them with high affinity has been successfully fabricated. Mfold (multiple folding) secondary structure simulation and molecular truncation were both utilized to obtain the most effective binding region from the parental full-length (39-mer) aptamer. The results show that the PAE-binding affinity of the truncated 24-mer aptamer produced by removing nonessential flanking nucleotides was improved by 1.5-fold. The linear range of TP detection is 0.003-10 μg/L, and the limit of detection is 1 ng/L. Notably, our study provides new insights into the group-targeting identification of certain pollutants and determination of their total amounts, exhibiting great potential for practical applications.

Development of an immunochromatographic assay as a screen for detection of total phthalate acid esters in cooking oil

Phthalate acid esters (PAEs) contamination raised concerns as a result of migration from food packaging and environmental exposure. Because of the adverse effects of PAE reported in humans, the aim of this study was to examine the ability to screen for the detection these chemicals as an indicator of potential exposure. Too develop a sensitive screening test to determine PAE, a specific polyclonal antibody against phthalic acid (PA), the hydrolysate of PAEs, was used as a marker of total PAEs. This method involved the use of 4-aminophthalic acid (APA) as an immunizing hapten to generate antibody. Subsequently, this antibody conjugated with labeled gold nanoparticles (GNPs) was then used to develop an immunochromatographic assay (ICA) for visually detecting PA. After establishing optimal assay conditions, the ICA strip detected visually PA at 3 μg/ml rapidly in less than 5 min. Further, this assay exhibited reliable specificity for PA with no apparent cross-reactivity with structurally related PAEs. A significant correlation between data obtained with the ICA strip and high-performance liquid chromatography (HPLC) analysis was achieved using cooking oils as model spiked samples. The proposed use of ICA offers an effective tool for rapid on-site screening for total PAEs in cooking oils.

Selection of Group-Specific Phthalic Acid Esters Binding DNA Aptamers via Rationally Designed Target Immobilization and Applications for Ultrasensitive and Highly Selective Detection of Phthalic Acid Esters

Phthalic acid esters (PAEs) are ubiquitous in the environment, and some of them are recognized as endocrine disruptors that cause concerns on ecosystem functioning and public health. Due to the diversity of PAEs in the environment, there is a vital need to detect the total concentration of PAEs in a timely and low-cost way. To fulfill this requirement, it is highly desired to obtain group-specific PAE binders that are specific to the basic PAE skeleton. In this study, for the first time we have identified the group-specific PAE-binding aptamers via rationally designed target immobilization. The two target immobilization strategies were adopted to display either the phthalic ester group or the alkyl chain, respectively, at the surface of the immobilization matrix. The former enabled the rapid enrichment of aptamers after four rounds of selection. The top 100 sequences are cytosine-rich (44.7%) and differentiate from each other by only 1-4 nucleotides at limited locations. The top two aptamers all display the nanomolar dissociation constants to both the immobilized target and the free PAEs [dibutyl phthalate (DBP), butyl benzyl phthalate (BBP), bis(2-ethylhexyl) phthalate (DEHP)]. We further demonstrate the applications of the aptamers in the development of high-throughput PAE assays and DEHP electrochemical biosensors with exceptional sensitivity [limit of detection (LOD), 10 pM] and selectivity (>10⁵-fold). PAE aptamers targeting one of the most sought for targets thus offer the promise of convenient, low-cost detection of total PAEs. Our study also provides insights on the aptamer selection and sensor development of highly hydrophobic small molecules.

Methods for the Determination of Endocrine-Disrupting Phthalate Esters

Phthalates are endocrine disruptors frequently occurring in the general and industrial environment and in many industrial products. Moreover, they are also suspected of being carcinogenic, teratogenic, and mutagenic, and they show diverse toxicity profiles depending on their structures. The European Union and the United States Environmental Protection Agency (US EPA) have included many phthalates in the list of priority substances with potential endocrine-disrupting action. They are: dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), butylbenzyl phthalate (BBP), diethylhexyl phthalate (DEHP), di-iso-nonyl phthalate (DINP), di-iso-decyl phthalate (DIDP), di-n-decyl phthalate (DnDP), and dioctyl phthalate (DOP). There is an ever-increasing demand for new analytical methods suitable for monitoring different phthalates in various environmental, biological, and other matrices. Separation and spectrometric methods are most frequently used. However, modern electroanalytical methods can also play a useful role in this field because of their high sensitivity, reasonable selectivity, easy automation, and miniaturization, and especially low investment and running costs, which makes them suitable for large-scale monitoring. Therefore, this review outlines possibilities and limitations of various analytical methods for determination of endocrine-disruptor phthalate esters in various matrices, including somewhat neglected electroanalytical methods.

Simultaneous GC-MS determination of seven phthalates in total and migrated portions of paper cups

Phthalate acid esters are widely used as plasticizers to impart plastic flexibility in various industrial applications. In this study, the content of seven phthalates, dibutyl phthalate (DBP), benzyl butyl phthalate (BBP), di-(2-ethylhexyl) adipate (DEHA), di-2-ethylhexyl phthalate (DEHP), di-n-octyl phthalate (DNOP), di-isononyl phthalate (DINP), and di-isodecyl phthalate (DIDP) were determined in paper cups using gas chromatography-mass spectrometry (GC-MS). In addition, the potential migration of these seven phthalates from paper cups into various food stimulants under different conditions was evaluated. The levels of DBP, DEHA, DEHP, and DNOP were in the ranges of 0.07-3.14, 0.16-42.69, 0.45-58.56, and 0.3-2.4 mg/kg, respectively. Meanwhile, BBP, DINP, and DIDP were not detected in most of the tested samples. In the migration test, DEHA was released to 50 % ethanol and n-heptane in a time-dependent manner and the maximum migration levels were 65.62 ± 3.61 and 95.56 ± 19.76 μg/L, respectively. The release of other phthalates was very low or negligible. These results demonstrated that paper cups are not a significant source of phthalate exposure; however, DEHA could be released from paper cups into alcoholic beverages or oily liquid beverages in the human diet.

Migrated phthalate levels into edible oils

The determination of phthalates in edible oils (virgin olive oil, olive oil, canola oil, hazelnut oil, sunflower oil, corn oil) sold in Turkish markets was carried out using gas chromatography-mass spectrometry. Mean phthalate concentrations were between 0.102 and 3.863 mg L(-1) in virgin olive oil; 0.172 and 6.486 mg L(-1) in olive oil; 0.501 and 3.651 mg L(-1) in hazelnut oil; 0.457 and 3.415 mg L(-1) in canola oil; 2.227 and 6.673 mg L(-1) in sunflower oil; and 1.585 and 6.248 mg L(-1) in corn oil. Furthermore, the influence of the types of oil and container to the phthalate migration was investigated. The highest phthalate levels were measured in sunflower oil. The lowest phthalate levels were determined in virgin olive oil and hazelnut oil. The highest phthalate levels were determined in oil samples contained in polyethylene terephthalate.

Plasticizer contamination in edible vegetable oil in a U.S. retail market

With the wide application of plastics, the contamination of plasticizers migrating from plastic materials in the environment is becoming ubiquitous. The presence of phthalates, the major group of plasticizers, in edible items has gained increasingly more concern due to their endocrine disrupting property. In this study, 15 plasticizers in 21 edible vegetable oils purchased from a U.S. retail market were analyzed using gas chromatograph-mass spectrometry. Di(2-ethylhexyl) phthalate (DEHP) and diisobutyl phthalate (DiBP) were detected in all oil samples. Benzylbutyl phthalate (BzBP), dibutyl phthalate (DBP), and diethyl phthalate (DEP) were detected at a rate of 95.2, 90.5, and 90.5%, respectively. The detection rates for all other plasticizers ranged from 0 to 57.1%. The content of total plasticizers in oil samples was determined to be 210-7558 μg/kg, which was comparable to the content range in oil marketed in Italy. Although no significant difference (p = 0.05) in the total content of plasticizer was observed among oil species (soybean, canola, corn, and olive), the wider range and higher average of total content of plasticizers in olive oil than other oil species indicated the inconsistence of plasticizer contamination in olive oil and a possible priority for quality monitoring. No significant difference (p = 0.05) in the total content of plasticizers was found among glass-bottle (n = 4), plastic-bottle (n = 14), and metal-can (n = 3) packaging, implying that oil packaging is not the major cause of plasticizer contamination. The daily intake amount of plasticizers contained in edible oil on this U.S. retail market constituted only a minimum percentage of reference dose established by US EPA, thus no obvious toxicological effect might be caused. However, the fact that DEHP content in two olive oils exceeded relevant special migration limits (SMLs) of Europe and China might need attention.

Synthesis and Evaluation of Molecularly Imprinted Polymer for the Determination of the Phthalate Esters in the Bottled Beverages by HPLC

A molecularly imprinted polymer (MIP) was prepared in acetonitrile by bulk polymerization, using di-n-octylphthalate (DOP) as a template molecular,α-methacrylic acid (MAA) as a functional monomer, and ethylene dimethacrylate (EDMA) as a crosslinker. Characterization and evaluation of the prepared MIP were carried out by scanning electron microscope (SEM), infrared absorption spectroscopy (IR), and the Scatchard analysis, respectively. Through the optimization of washing solvent, eluting solvent amount, flow rate of loading solution, and loading sample volume, an analysis method was established for DOP related compounds with high selectivity and sensitivity by using the selective molecularly imprinted solid-phase extraction (MI-SPE) technique. Moreover, under the optimal conditions, the extraction effects were comparatively investigated by using MIP cartridge, NIP cartridge, and the commercial PLS cartridge used especially for phthalic acid esters (PAEs), respectively. The results showed that the recoveries of spiked PAEs are in the range of 90.4%–97.8% with the relative standard deviation (RSD) of 1.6%–3.8% on the resulted MIP cartridge, whilst lower recoveries were obtained ranging from 80.2% to 88.9% with an RSD of 1.4%–5.2% on the commercial PLS cartridge.

Development of multiresidue analysis for twenty phthalate esters in edible vegetable oils by microwave-assisted extraction-gel permeation chromatography-solid phase extraction-gas chromatography-tandem mass spectrometry

A novel multiresidue analysis method is developed for the determination of twenty phthalate esters at the μg/kg level in edible vegetable oils by microwave-assisted extraction-gel permeation chromatography-solid phase extraction-high resolution gas chromatography-tandem mass spectrometry (MAE-GPC-SPE-HRGC-MS/MS). The samples were extracted with methanol under microwave incubation. Cleanup was carried out with GPC followed by a further C18 SPE column and then separated by the HP-5MS capillary column under a temperature program. The eluents were qualitatively and quantitatively determined by tandem mass analyzer with selected reaction monitoring (SRM) type and positive ion mode. The calibration curves showed good linearity in the range 5 μg/kg to 2.50 mg/kg with correlation coefficients larger than 0.999. Low detection limits (LODs) of 0.218-1.367 μg/kg and quantification limits (LOQ) of 0.72-4.51 μg/kg were achieved. The mean recoveries were in the range from 93.04% to 104.6% at 5, 15, and 40 μg/kg spiked levels, and the relative standard deviations (RSDs) were in the range of 1.01% and 5.26% (n = 7). This method could potentially overcome the interference from large amounts of lipids and pigment. The real sample test showed this method can be used for sensitive and accurate determination and confirmation of phthalate ester residues in high-fat and complex samples.

Determination of dimethyl phthalate in environment water samples by a highly sensitive indirect competitive ELISA

Recent controversy over the discovery of clouding agents containing the banned chemical di(2-ethylhexyl) phthalate in beverages in 2011 in Taiwan has caused public concerns. For the detection of dimethyl phthalate (DMP) in environment water samples, an indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) was developed in this paper. Dimethyl 4-aminophthalate (4-DMAP) was covalently attached to bovine serum albumin as immunogen by a diazotization method. The conjugation of DMAP and ovalbumin as coating antigen was obtained in the same way. Polyclonal antibody was obtained from New Zealand white rabbits. Under the optimized conditions, DMP was detected in the concentration range of 0.02-419 ng/mL with a detection limit of 0.01 ng/mL. The proposed method has been applied to the analysis of river water, lake water, and rain water samples. Satisfactory recoveries were obtained ranging from 90.6% to 105.5%. The cross-reactivities of the anti-DMP antibody to seven structurally related phthalate esters were below 10%. The data demonstrated that the ic-ELISA method described in our study is a simple, sensitive, and specific method and showed that this assay is a reliable tool to detect DMP in water samples.