Carbon nanotube composite microspheres as a highly efficient solid-phase microextraction coating for sensitive determination of phthalate acid esters in water samples

In this study, the levels of six PAEs [bis (2-ethylhexyl) phthalate (DEHP), butyl benzyl phthalate (BBP), dibutyl phthalate (DBP), diethyl phthalate (DEP), dimethyl phthalate (DMP) and di-n-octyl phthalate (DNOP)] were determined from four types of bottled water)non-carbonated, mineral, carbonated and carbonated flavoured) using MSPE method (magnetic solid phase extraction) and GC/MS technique (gas chromatography/mass spectrometry). The mean concentration of total PAEs was 6.11 ± 1.43 µg/L. The mean concentration of DEHP was 2.22 ± 0.76 µg/L and was lower than the United States Environmental Protection Agency (USEPA) standard level in drinking water (6 μg/L for DEHP). The highest mean level of total PAE was observed in carbonated water (7.43 ± 2.03 μg/L) and the lowest mean level of total PAE was observed in non-carbonated water (5.15 ± 0.41 μg/L). The Monte Carlo method was applied to calculate the Target Hazard Quotient (THQ), Chronic Daily Intake (CDI), and Incremental Life Cancer Risk (ILCR) indexes. In all samples, the rank order of the estimated THQ values based on the 95% percentile was DEHP (4.77E-4) > DBP (2.25E-5) > BBP (1.99E-5) > DEP (2.75E-6) and there would be unlikely non-carcinogenic risks for consumers (THQ<1). The incremental lifetime cancer risk assessment revealed that phthalate esters (DEHP) in evaluated bottled water samples did not pose a serious concern to humans.

Phthalic acid esters (PAEs) are ubiquitous environmental pollutants and are recognized as a threat to the environment and agricultural product safety across the world. In order to investigate the level of PAEs in garlic, soils, and agricultural films from Pizhou City, Jiangsu province, China, 11 garlic samples, 106 soil samples, and 4 agricultural film samples were collected and analyzed using GC-MS. In addition, the uptake and transport characteristics of six PAEs compounds classified as priority pollutants by the United States Environmental Protection Agency (EPA) in the garlic cultivar Daqingke were investigated under hydroponic conditions. The results indicated that dibutyl phthalate (DBP) and di-(2-ethylhexyl) phthalate (DEHP) were the dominant PAEs species in garlic cloves of the different garlic varieties from Pizhou City. The average contents of DBP and DEHP in garlic cloves were 0.611 mg·kg-1 and 0.167 mg·kg-1, respectively, which were significantly higher than those of the commercial varieties of garlic. The concentrations of DBP and DEHP differed in three tissues of garlic bulbs, ordered as the skin of garlic bulb>skin of garlic clove>garlic clove. Dimethyl phthalate (DMP), diethyl phthalate (DEP), diisobutyl phthalate (DIBP), DBP, and DEHP were the main PAEs species and were detected in all the surface soils collected from Pizhou City. Compared with the soil allowable concentrations of the six PAEs in the United States, the DMP and DBP concentrations in approximately 100% and 63.2% of soil samples exceeded the recommended allowable concentrations set by the EPA. However, the levels of DEP, DIBP, and DEHP in the soils were below the maximum allowable concentrations set by the EPA. Nevertheless, the average content of DEHP in soils was 486 μg·kg-1 and was found to be much higher than that in the other four PAEs. Six PAEs, including DMP, DEP, DIBP, DBP, butyl benzyl phthalate (BBP), and DEHP, were detected in all the agricultural film samples. Among them, the contents of DBP and DEHP in the agricultural films were the highest, accounting for 53.7%-63.2% of the total PAEs. The amount of PAEs present in the residual film was significantly lower than that in the new film, and all six PAEs were detected in garlic or soil samples, suggesting that agricultural film can be an important source of PAEs in garlic farming soils and garlic. Furthermore, the garlic plants absorbed DMP and DEP efficiently from the substrate and showed higher translocation factors (TFs) for DMP and DEP than those for DBP, BBP, DEHP, and di-n-octyl phthalate (DnOP), resulting in a higher accumulation of DMP and DEP in the over-ground parts of garlic. In contrast, DBP and BBP in roots of garlic displayed higher bioconcentration factors (57.4 and 81.5, respectively) compared to those of the other four PAEs, whereas the TFs of DBP and BBP were lower; this may have contributed to the high accumulation of DBP in garlic bulbs. The BCFs and TFs of DEHP and DnOP in garlic were relatively lower, but the DEHP had been detected in all garlic cloves, which may be a result of the higher DEHP contents in soils.

The efficient extraction of phthalic acid esters (PAEs) is challenging due to their extremely low concentration, complicated matrices and hydrophilicity. Herein, hollow microspheres, as an ideal coating, possess significant potential for solid-phase microextraction (SPME) due to their fascinating properties. In this study, multiwalled carbon nanotube hollow microspheres (MWCNT-HMs) were utilized as a fiber coating for the SPME of PAEs from tea beverages. MWCNT-HMs were obtained by dissolving the polystyrene (PS) cores with organic solvents. Interestingly, MWCNT-HMs well maintain the morphology of the MWCNTs@PS precursors. The layer-by-layer (LBL) assembly of MWCNTs on PS microsphere templates was achieved through electrostatic interactions. Six PAEs, di-ethyl phthalate (DEP), di-iso-butyl phthalate (DIBP), di-n-butyl phthalate (DBP), benzyl butyl phthalate (BBP), di-2-ethylhexyl phthalate (DEHP) and di-n-octyl phthalate (DOP), were selected as target analytes for assessing the efficiency of the coating for SPME. The stirring rate, sample solution pH and extraction time were optimized by using the Box-Behnken design. Under optimal working conditions, the proposed MWCNT-HMs/SPME was coupled with gas chromatography-tandem mass spectrometry (GC-MS/MS) to achieve high enrichment factors (118-2137), wide linearity (0.0004-10 μg L-1), low limits of detection (0.00011-0.0026 μg L-1) and acceptable recovery (80.2-108.5%) for the detection of PAEs. Therefore, the MWCNT-HM coated fibers are promising alternatives in the SPME method for the sensitive detection of PAEs at trace levels in tea beverages.

Growing concern that phthalic acid esters (PAE) may present a health hazard and possible deleterious effects on the ecological system has led to increased interest in the more subtle toxicity of those compounds. Although the acute toxicity of PAEs as a group is quite low, the intrinsic cellular toxicity increases with molecular weight. Whether the intrinsic toxicity is great enough to exert a significant effect in vivo at the typically low levels of solubility of PAEs is of primary importance to the assessment of their potential hazard. This paper reviews work reported on the teratogenicity of PAEs and new work on the mutagenicity, cellular toxicity, and absorption, excretion, and distribution of those compounds. The relationship of in vitro and in vivo response is discussed.

Determination of phthalic acid esters in water samples using core-shell poly(dopamine) magnetic nanoparticles and gas chromatography tandem mass spectrometry

Herein, the catchment-wide temporal dynamics and potential ecotoxicological risk of phthalic acid esters (PAEs) in aquatic ecosystems were assessed. Specifically, water samples were collected for a period of six consecutive months from seven selected sites, i.e., covering both dry and wet seasons for seasonal variabilities. The appraised PAEs comprised dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DBP), benzylbutyl phthalate (BBP), diphenyl phthalate (DPP), di-n-hexyl phthalate (DHP), bis(2-ethylhexyl) phthalate (DEHP), di-n-octyl phthalate (DOP), diisodecyl phthalate (DiDP) and diisononyl phthalate (DiNP)) in municipal wastewater effluents, rivers and dam. Their concentrations were quantified using a gas chromatography–flame ionisation detector (GC–FID) via the liquid–liquid extraction mode. The appraised PAEs were ubiquitous in the selected sampling points, with DBP being the most abundant PAE homologue throughout the assessed localities. In particular, quantifiable concentrations were 18.9, 37.9 and 11.5 μg/L for DBP in wastewater effluents, rivers and the dam catchment, respectively, and for overall Σ10PAEs of minimum, mean and maximum of 0.492, 3.6 ± 9.82 and 63.2 μg/L, respectively. In addition, PAE concentrations in the effluents, rivers, and dam samples showed no significant differences with p &lt; 0.05. The overall prominent sequence for ∑PAEs registered: 53.3 &gt; 10.1 &gt; 10.0 &gt; 9.8 &gt; 4.3 &gt; 2.5 &gt; 1.8 &gt; 1.7 &gt; 1.1 &gt; 0.9% for DBP &gt; DEHP &gt; DiDP &gt; DOP &gt; DHP &gt; DPP &gt; BBP &gt; DMP &gt; DEP &gt; DiNP, respectively. The ecotoxicological risk assessment (risk quotient method) showed that DBP and DiDP posed high risk (RQ ≥ 1), and DOP, DEHP, DHP, DiNP and BBP posed median risk to aquatic organisms (0.1 ≤ RQ &lt; 1), while the risk from DMP and DEP was minimal (RQ &lt; 0.1). Additionally, DBP, DEHP, DOP, DPP and DiDP were higher than the water criterion (3 μg/L) of PAEs recommended by the United States Environmental Protection Agency (USEPA) for the protection of aquatic life. Findings from this study should go a long way in guiding regulators, custodians and catchment management forums, along with interested and affected parties, regarding the status and potential ecotoxicological effects of PAEs in the receiving environment.

Phthalate acid esters (PAEs) are widely used in various industries where the usage of PAEs containing products leads to the entrance of PAEs into wastewater treatment plant. During wastewater treatment processes, higher molecular weight PAEs including dibutyl phthalate (DBP), di-(2-ethylhexyl) phthalate (DEHP) and butylbenzyl phthalate (BBP) could be easily attached to the surfaces of sewage sludge and transferred to sludge treatment units. Therefore, sludge pretreatment to remove PAEs before sludge treatment and disposal is necessary. In this study, alkalization combined with ultrasound was adopted for removing the PAEs from sewage sludge. The initial DBP, DEHP and BBP concentrations in sewage sludge were 718, 215 and 8 mg/kg-dw, respectively. Pretreatments were carried out by adding sodium hydroxide (NaOH) individually for designed concentrations to sewage sludge and mixing gently for 24 hours followed by sonication. The frequency of ultrasound was 20 kHz with the ultrasound power density and power intensity of 1 W/mL and 55 W/cm2. The total solids (TS) concentration of the sewage sludge was 3%. The central composite design (CCD) was used in this study to find out the better operation condition which the designed parameters were NaOH concentration (0 - 80 mM) and sonication time (0 - 15 min). NaOH alkalization of sewage sludge led to DBP removal only; removals of DEHP and BBP were almost zero. Increase of the soluble chemical oxygen demand (SCOD) in pretreated sewage sludge was 8.37 mg/L per 1 mM NaOH addition. Alkalization was responsible for more than 90% of DBP removal and more than 60% in SCOD increase in the alkalization-sonication pretreatment. The optimal NaOH concentration and sonication time were estimated as 68 mM and 10 min based on the CCD and response surface plots, respectively.

A review on phthalate esters or phthalic acid esters (PAEs), chemicals of concern since a few decades ago that are widely used as plasticizers in food processing and packaging, is presented taking into account the background of such compounds, the metabolism, human exposure to PAEs, the sources and occurrence in food as well as the toxicological aspects and human health effects. In addition, 45 novel research articles that were published between 2002 and 2017 were identified and their results were tabulated showing the PAEs analysed, food matrix of PAEs, methods of sample preparation/extraction, methods of instrumental analysis and quantitation, percentage recovery and limit of detection (LOD) of the instrument for ease of comparison and referencing. In general, it was found that in the last 15 years, the number of PAEs analysed has increased from the commonly analysed 8 PAEs, namely dimethyl phthalate (DMP), diethyl phthalate (DEP), diisobutyl phthalate (DIBP), di-n-butyl phthalate (DBP), butyl benzyl phthalate (BBP), dicyclohexyl phthalate (DCHP), di-n-octyl phthalate (DNOP) and di-(2-ethylhexyl) phthalate (DEHP) to as many as 23 PAEs. The methods of sample preparation have also progressed from the simple liquid-liquid extraction using organic solvents to solid-phase microextraction techniques to the more recent head-space or direct immersion solid-phase microextraction methods. Whereas for the analysis of PAEs, gas chromatography and liquid chromatography are still the preferred methods with improved LOD of analysis ranging from approximately 10 ppm for fatty foods to 1–60 ppt for water, juices and cooking oil samples.

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 0.3-2.4mg/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 ± 19.76μg/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.

Simultaneous GC-MS determination of eight phthalates in total and migrated portions of plasticized polymeric toys and childcare articles.

Exxon Chemical as exclusive distributor of ICI speciality plasticizers

Quantitative Determination and Confirmation of Identity of Trace Amounts of Dialkyl Phthalates in Environmental Samples

The occurrence of nine phthalic acid esters (PAEs) were determined in indoor dust samples collected from vehicle repair shops, waste processing workshops, and homes in Vietnam. Concentrations of total PAEs ranged from 585 to 153,000 (median 33,400ng/g), which fall in the lower end of global range. The PAE levels in workplace dust (median 49,100; range 9210-153,000ng/g) were significantly higher than those in house dust (median 23,700; range 585-83,700ng/g), indicating waste processing activities as potential PAE sources. The most predominant compound was di-(2-ethyl)hexyl phthalate (DEHP), accounting for 62 ± 18% of total PAEs. Other major compounds were benzyl butyl phthalate (BzBP) (10 ± 12%), di-n-butyl phthalate (DnBP) (9.7 ± 7.7%), di-n-octyl phthalate (DnOP) (7.9 ± 8.1%), and diisobutyl phthalate (DiBP) (6.9 ± 5.0%). Proportions of BzBP and DnBP in some workplace dust samples were markedly greater than in common house dust, suggesting specific emission sources. Daily intake doses of selected PAEs (e.g., DnBP, DiBP, BzBP, and DEHP) through dust ingestion were much lower than reference doses, implying acceptable levels of risk.

A novel magnetic plasticizer molecularly imprinted polymer adsorbing material (MIP@mSiO2 -β-CD@Fe3 O4 ) was successfully synthesized for the determination of six phthalic acid esters in water, milk, and wine samples. The molecularly imprinted polymers were prepared via precipitation polymerization and a surface molecular imprinting technique, using a cyclodextrin-modified magnetic meso-porous material (mSiO2 -β-CD@Fe3 O4 ) as a magnetic supporter, dibutyl phthalate and butyl benzyl phthalate as the dual template molecules, methacrylic acid as the functional monomer, and ethyleneglycol dimethacrylate as the cross-linking agent. The polymers were characterized by scanning electron microscopy, IR spectroscopy, and X-ray powder diffraction. Thermogravimetric analysis and static and dynamic adsorption experiments were carried out to assay its stability and selectivity. Under optimal experimental conditions, a magnetic solid-phase extraction with MIP@mSiO2 -β-CD@Fe3 O4 coupled to gas chromatography and mass spectrometry method was successfully developed for the determination of phthalic acid esters. The established method achieved a good linear range of 0.10∼8.00μg/mL (R>0.99) and a low detection limit within the range of 1.0∼5.0μg/L. An average recovery rate of 80.2∼103% with relative standard deviation<6.7% was obtained upon the application of the developed method to detect phthalic acid esters in actual aqueous samples.

Water and bottom sediment samples were taken from the Zhenjiang section of the lower reach of Yangtze River, China during the autumn of 2011, aimed to study the pollution levels of six kinds of phthalate acid esters (PAEs). Water samples were prepared by solid-phase extraction (SPE) and analyzed by gas chromatography-mass spectrometry (GC–MS), with spiked recoveries ranging from 33.5% to 121.0%. Sediment samples were pretreated using ultrasonic-assisted organic solvent extraction, with recoveries varying from 43.7% to 107.6%. Results showed that the concentration levels of PAEs are below the limit of detection (LOD) –63.3μg/L in the water samples of Yangtze River. Tongji River water are severely contaminated by PAEs, with the concentrations of di-n-butyl phthalate (DnBP) up to 613ug/L. Four of PAEs were detected in the tap water of Zhenjiang. It was also found that all of detected PAEs are dominantly partitioned on suspended solids in water samples. The concentrations of PAEs in sediment samples are ranged from &lt;LOD to 7.5mg/kg.