Recent advances in analysis of phthalate esters in foods

Facile magnetization of covalent organic framework for solid-phase extraction of 15 phthalate esters in beverage samples

Phthalate esters (PAEs), a category of widely used plasticizers, are tend to migrate from plastic packaging to drinks. In this paper, we develop a simple and rapid coprecipitation method for synthesis of a magnetic covalent organic framework (COF) adsorbent. The fabricated COF-(TpBD)/Fe₃O₄ was applied to magnetic solid phase extraction (MSPE) of 15 phthalate esters (PAEs) for subsequent GC-MS/MS determination in beverage samples. The as-synthesized magnetic adsorbent exhibited great potential in PAEs analysis with a limit of detection of 15 PAEs ranged from 0.005 to 2.748 μg L^-1 (S/N = 3). The intra-day and inter-day relative standard deviations (RSD) value of the PAEs were less than 8.8% and 9.9%, respectively. The adsorbent can be reused after washing with methanol. The developed method was successfully applied for the determination of trace PAEs in eight beverages with recoveries ranging from 79.3% to 121.8% and RSDs were less than 11.9%. This work provides a simple magnetization process, which facilitates the application of COFs for enrichment and separation of PAEs in beverages with different matrices.

Quantitative structure-retention relationships of the chromatographic retentions of phthalic acid ester contaminants in foods

The harmful health effects caused by phthalic acid esters have been supported from the increasing scientific evidence, developing the efficient methodologies to monitor the levels of phthalic acid esters in various foods become especially important from the aspects of human exposure assessment and their migration mechanistic understanding. In this study, quantitative structure-retention relationship studies on both the gas and liquid chromatographic retention times of 23 phthalic acid esters were performed by genetic function approximation, and the optimal quantitative structure-retention relationship models (r²  > 0.980, r² _CV  > 0.960, and r² _pred  > 0.865) passed the statistical tests of cross-validation, randomization, external prediction, Roy' r_m ² metrics, Golbraikh-Tropsha' criteria and applicability domain. The established predictive models elucidate the structural requirements for the retention of phthalic acid esters over different chromatographic columns, which were finally used to predict the retention times of 11 new phthalic acid esters. Hopefully, this work could provide useful guidelines for better understanding and accurate prediction of the retention behavior of undetermined phthalic acid esters when lacking standard samples or under poor experimental conditions, and make the simultaneous identification and quantification of numerous phthalic acid esters possible.

Estimates of dietary exposure of Spanish population to packaging contaminants from cereal based foods contained in plastic materials

Food packaging may be a potential source of contamination, through the migration of chemicals from the packaging into the food, thus food consumption is an important route of human exposure to packaging contaminants. In the present study an approach to estimate the exposure to different chemicals transferred from food packaging was designed. As a first step a GC-MS screening was conducted to identify potential contaminants in the materials. Secondly, different chemicals previously identified in the packaging materials were selected for exposure assessment. The proposed methodology was applied to cereal based foods packed with plastic packaging. A variety of chemicals including e.g. acetyl tributyl citrate (ATBC), bis (2-ethylhexyl) adipate (DEHA) and diethyl phthalate (DEP) among others were identified and analyzed in the foodstuffs. For this purpose a LC-MS/MS method was developed. The selected foodstuffs were pooled into three groups according to the population age (12-35 months, 3-9 years and 10-17 years) and based on the Spanish consumption data (Enalia). In general, ATBC mean exposure was higher than that of phthalates and DEHA for the three groups considered, with mean dietary exposure values ranging from 1.01 μg/kg bw/day (pool 12-35 months) to 2.01 μg/kg bw/day (pool 3-9 years).

Automated on-line monitoring of the TiO2-based photocatalytic degradation of dimethyl phthalate and diethyl phthalate

An automated on-line system for monitoring the TiO₂-based photocatalytic degradation of dimethyl phthalate and diethyl phthalate.

Combination of dispersive solid phase extraction and deep eutectic solvent-based air-assisted liquid-liquid microextraction followed by gas chromatography-mass spectrometry as an efficient analytical method for the quantification of some tricyclic antidepressant drugs in biological fluids

A dispersive solid phase extraction coupled with deep eutectic solvent-based air-assisted liquid-liquid microextraction has been developed and applied to the extraction and preconcentration of some tricyclic antidepressant drugs in the human urine and plasma samples prior to their determination by gas chromatography-mass spectrometry. In this method, a sorbent (C₁₈) is first added into an alkaline aqueous sample and dispersed by vortexing. By this action, the analytes are adsorbed onto the sorbent. Then, the sorbent particles are isolated from the aqueous solution by centrifugation. Afterward, a deep eutectic solvent, prepared from choline chloride and 4-chlorophenol is used to desorb the analytes from the sorbent. Subsequently, the supernatant solution is removed and added into an alkaline deionized water placed into a test tube with a conical bottom. The resulting mixture is rapidly sucked into a glass syringe and then injected into the tube. This procedure is repeated for several times and a cloudy solution consisting of fine droplets of deep eutectic solvent dispersed into the aqueous phase is formed. After centrifuging the obtained cloudy solution, the tiny droplets of the extractant, containing the extracted analytes, settle at the bottom of the tube. Finally, an aliquot of the extractant is taken and injected into the separation system for quantitative analysis. Several significant factors affecting the performance of the proposed method are evaluated and optimized. Under optimum extraction conditions, the method shows low limits of detection in the ranges of 5-10, 8-15 and 32-60 ng L^-1 in deionized water, urine, and plasma, respectively. Enrichment factors are observed to be between 325 to 385 in deionized water, 155 to 185 in urine, and 64 to 72 in plasma. Extraction recoveries are in the range of 65-77 (in deionized water), 62-74 (in urine), and 64-72% (in plasma). The relative standard deviations of the proposed method are ≤ 6% for intra- (n = 6) and inter-day (n = 4) precisions at a concentration of 200 ng L^-1 of each analyte. Finally, the applicability of the introduced method is investigated by analyzing the selected drugs in different biological fluids. In the proposed method, for the first time, a deep eutectic solvent composed of safe, cheap, and biodegradable compounds was synthesized and used (at μL-level) as an elution and extraction solvent, simultaneously which led to omit the consumption of toxic organic solvents. This represents a significant advantage in the era of green chemistry. In addition, the introduced method is sensitive, simple in operation, rapid, and efficient.

Critical evaluation of several techniques for the analysis of phthalates and terephthalates: Application to liquids used in electronic cigarettes

This study describes several original methods that were developed with the goal of measuring phthalates and terephthalates. These methods include gas chromatography/mass spectrometry (GC/MS), GC/MS/MS, liquid chromatography with UV detection (LC/UV), LC/MS, and LC/MS/MS. The study compares the advantages and disadvantages of these methods and their applicability to measuring phthalates and terephthalates in the liquids used in electronic cigarettes (e-liquids). The analytes evaluated include eight phthalates and two terephthalates. The phthalates were diethyl, dibutyl, benzyl butyl, diphenyl, bis(2-ethylhexyl), di-n-octyl, diisononyl and diisodecyl. The terephthalates were dimethyl and bis(2-ethylhexyl). Intentionally, no cleanup or concentration step were used in the methods. The methods used two chromatographic standards, dimethyl phthalate-3,4,5,6-d₄, and di-(2-ethylhexyl) phthalate-3,4,5,6-d₄. All techniques were validated for selectivity/specificity, precision, sensitivity (evaluation of LOD and LOQ), as well as for repeatability and matrix interference. The GC methods were not adequate for the analysis of diphenyl, diisononyl, and diisodecyl phthalates which were not volatile enough to be seen in the conditions used for the GC separation. Also, alcohols should not be used as solvents for the injection of the sample in the GC system to avoid transesterification in the hot injection port. The single quadrupole MS detection in GC offers sensitivities around 1 μg/mL in the e-liquid and was not sensitive enough for the analysis of trace phthalates and terephthalates. Compared to all evaluated methods, the MS/MS detection in GC offered the best sensitivity (below 10 ng/mL in the e-liquid). The LC is adequate for the separation of all the evaluated analytes. However, the UV detection in LC does not offer good sensitivity compared to all the other techniques. The MS detection in LC provides poor sensitivity for terephthalates, but better than the UV for the rest of the analytes. The MS/MS detection for LC offers slightly better sensitivity than the MS detection, but both LC/MS and LC/MS/MS were only able to measure levels above about 100 ng/mL of analytes in the e-liquid. A group of 39 e-liquids were analyzed by three of the evaluated procedures. Benzyl butyl phthalate, bis(2-ethylhexyl) terephthalate, and di-n-octyl phthalate were not detected in the e-liquids. Some of the other evaluated phthalates were present at trace levels in certain e-liquids while most e-liquids did not contain phthalates at detectable levels.

Magnetic solid phase extraction using Fe3O4@SiO2@C8 nanoparticles performed in a narrow-bore tube followed by dispersive liquid–liquid microextraction for extraction and preconcentration of nine pesticides

In the present work, a new magnetic solid phase extraction method performed in a narrow-bore tube using synthesized Fe₃O₄@SiO₂@C₈ magnetic nanoparticles has been developed.

Study on the interaction between typical phthalic acid esters (PAEs) and human haemoglobin (hHb) by molecular docking

This work has evaluated the binding force between hHb and typcial PAEs (DMP, DEP, DPRP, DBP, DIBP, DHP and DPHP) using molecule docking technique. The DPHP with 3 aromatic rings has the strongest binding (-ΔG_binding: 6.0kcalmol^-1) than other PAEs (-ΔG_binding: 2.91∼4.48kcalmol^-1). The DMP with the lowest molecular weight has a high binding force (-ΔG_binding: 4.48kcalmol^-1), while the DHP with the highest molecular weight has the lowest binding force (-ΔG_binding: 2.91kcalmol^-1). When the length of side chain increases, the binding force trend to decrease, regarding the VDW forces and H-bonding. The lgK_ow-ΔG_binding plotting figure shows that a higher K_ow value is accompanied by a lower binding force. The aromatic ring existed in PAEs largely increases the binding force between the hHb and the PAEs. On the other hand, the PAEs with higher number of carbon, meaning a higher hydrophobicity, can enter into the hydrophobic space of hHb centre deeper and bond to different position. The aromatic ring decreases the depth of binding position in the hydrophobic space. This work provides basic data and a theoretical method to assess the transport and accumulation of PAEs in human body, and the cytotoxicity of PAEs to hBRCs.

Fast analysis of phthalates in freeze-dried baby foods by ultrasound-vortex-assisted liquid-liquid microextraction coupled with gas chromatography-ion trap/mass spectrometry

This paper is focused on the determination of phthalates (PAEs), compounds "plausibly" endocrine disruptors, in baby food products by means of a method based on ultrasound-vortex-assisted liquid-liquid microextraction coupled with GC-IT/MS (UVALLME-GC-IT/MS). Particularly, the whole procedure allows the determination of six phthalates such as DMP, DEP, DBP, iBcEP, BBP and DEHP. After dissolution of 0.1g product sample and addition of anthracene as Internal Standard, 250μL of n-heptane are used as extraction solvent. The solution, held for 5min on the vortex mixer and for 6min in an ultrasonic bath at 100W for favoring the solvent dispersion and consequently the analyte extraction, is centrifuged at 4000rpm for 30min. About 100μL of heptane are recovered and 1μL is injected into the GC-IT/MS. All the analytical parameters investigated are deeply discussed: under the best conditions, the percentage recoveries range between 96.2 and 109.2% with an RSD ≤10.5% whereas the Limit of Detections (LODs) and the Limit of Quantifications (LOQs) are below 11 and 20ngg^-1, respectively, for all the PAEs except for iBcEP (23 and 43ngg^-1, respectively). The linear dynamic range of this procedure is between 10 and 5000ngg^-1 with R² ≥0.92. The method has been applied to real commercial freeze-dried samples (chicken and turkey meats) available on the Italian pharmaceutical market: three PAEs were preliminary identified, i.e. DEP (14ngg^-1), DBP (11ngg^-1) and DEHP (64ngg^-1).

Widespread occurrence of phthalic acid esters in raw oilseeds in China used for edible vegetable oil production

Seven different phthalic acid esters (PAEs) were quantified in 124 samples of 16 types of oilseeds from China using a simplified GC-MS method. Di-2-ethylhexyl phthalate and di-n-butyl phthalate were found in all tested oilseed samples. Each made a high contribution to the summed total PAEs. Total PAE concentrations in 124 oilseeds ranged from 0.14 to 3.05 mg kg(-1), and the mean was 0.99 mg kg(-1). Mandulapalka (Cyperus esculentus) samples were the most severely contaminated among all the tested specimens; maize germ samples were least contaminated. Di-n-octyl phthalate and butylbenzyl phthalate were not detected in 12 and five types of oilseeds, respectively. Only eight samples contained all seven analytes. No difference was observed between woody oil-bearing plant and herbaceous oil-bearing plant in terms of PAEs content.

Phthalates in meat products in dependence on the fat content

The content of dibutylphthalate (DBP) and di-(2-ethylhexyl) phthalate (DEHP) in samples of packages intended for thermally processed meat products and release of phthalates from packages into meat products in dependence on the fat content were observed. 80 samples of packages were analyzed, 5 of them wereselected due to exceeding the specific migration limit. The raw meat was prepared, one type with the fat content of 10% and second one with the fat content of 50%. The both types of raw meat were analyzed for the content of DBP and DEHP and packed into chosen packages.The samples of meat products were thermally processed (70 ℃, 10 min in the core), stored until the expiration date at 4 °C and gradually analyzed after 1st, 7th, 14th, 21st and 28th day of storage. Determination of phthalates was carried out by high performance liquid chromatography (HPLC) in the Zorbax Eclipse C8column and by UV detection at a wavelength of 224 mm. The phthalate content in the raw meat was under the limit of detection. According to the EU Commission Regulation no. 10/2011 the specific migration limit of products intended for the contact with food for DEHP (max. 1.5 mg.kg-1of food stimulant and DBP max. 0.3 mg.kg-1 of food stimulant), wasexceeded already after first day of storage, in case of DBP in two samples with 10% of fat and after 7th day of storage in one sample. In the samples with 50% of fat, SML was exceeded after first day of storage in four samples and in one sample after 14th day of storage. Regarding DEHP in the samples with 10% of fat SML was exceeded after 1st day of storage in one sample and after 7th day of storage also in one sample and after 21st day of storage similarly in one sample. Four samples with 50% of fat had SML exceeded in case of DEHP already after 1st day of storage. By comparison of PAE migration depending on the fat content we concluded that leaching of PAE from a package into food was 2 - 21 times higher in samples with 50% of fat than in samples with 10% of fat. 

A porous carbon derived from amino-functionalized material of Institut Lavoisier as a solid-phase microextraction fiber coating for the extraction of phthalate esters from tea

In this work, a porous carbon derived from amino-functionalized material of Institut Lavoisier (C-NH2 -MIL-125) was prepared and coated onto a stainless-steel wire through sol-gel technique. The coated fiber was used for the solid-phase microextraction of trace levels of phthalate esters (diallyl phthalate, di-iso-butyl ortho-phthalate, di-n-butyl ortho-phthalate, benzyl-n-butyl ortho-phthalate, and bis(2-ethylhexy) ortho-phthalate) from tea beverage samples before gas chromatography with mass spectrometric analysis. Several experimental parameters that could influence the extraction efficiency such as extraction time, extraction temperature, sample pH, sample salinity, stirring rate, desorption temperature and desorption time, were investigated. Under the optimal conditions, the linearity existed in the range of 0.05-30.00 μg/L for green jasmine tea beverage samples, and 0.10-30.00 μg/L for honey jasmine tea beverage samples, with the correlation coefficients (r) ranging from 0.9939 to 0.9981. The limits of detection of the analytes for the method were 2.0-3.0 ng/L for green jasmine tea beverage sample, and 4.0-5.0 ng/L for honey jasmine tea beverage sample, depending on the compounds. The recoveries of the analytes for the spiked samples were in the range of 82.0-106.0%, and the precision, expressed as the relative standard deviations, was less than 11.1%.