Determination Of Phthalate Esters Research Articles

Simultaneous extraction and determination of phthalate esters in aqueous solution by yolk-shell magnetic mesoporous carbon-molecularly imprinted composites based on solid-phase extraction coupled with gas chromatography–mass spectrometry

A rapid, sensitive and accurate method for the simultaneous extraction and determination of five types of trace phthalate esters (PAEs) in environmental water and beverage samples using magnetic molecularly imprinted solid-phase extraction (MMIP–SPE) coupled with gas chromatography–mass spectrometry (GC–MS) was developed. A novel type of molecularly imprinted polymers on the surface of yolk-shell magnetic mesoporous carbon (Fe3O4@void@C–MIPs) was used as an efficient adsorbent for selective adsorption of phthalate esters based on magnetic solid–phase extraction (MSPE). The real samples were first preconcentrated by Fe3O4@void@C–MIPs, subsequently extracted by eluent and finally determined by GC–MS after magnetic separation. Several variables affecting the extraction efficiency of the analytes, including the type and volume of the elution solvent, amount of adsorbent, extraction time, desorption time and pH of the sample solution, were investigated and optimized. Validation experiments indicated that the developed method presented good linearity (R2>0.9961), satisfactory precision (RSD<6.7%), and high recovery (86.1–103.1%). The limits of detection ranged from 1.6ng/L to 5.2ng/L and the enrichment factor was in the range of 822–1423. The results indicated that the novel method had the advantages of convenience, good sensitivity, and high efficiency, and it could also be successfully applied to the analysis of PAEs in real samples.

Determination of phthalate esters at trace level from environmental water samples by magnetic solid-phase extraction with Fe@SiO2@polyethyleneimine magnetic nanoparticles as adsorbent prior to high-performance liquid chromatography.

In this work, polyethyleneimine grafted silica-coated nanoscale zero valent iron (Fe@SiO2@PEI) has been successfully synthesized and was investigated to be an effective adsorbent for efficient enrichment of five phthalate esters such as diphenyl phthalate, dibenzyl phthalate, butyl benzyl phthalate, diphenyl isophthalate, and dicyclohexyl phthalate (DPP, DBP, BBP, DPIP, and DCHP) from environmental water samples. The structure and morphology of the materials were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction(XRD). The parameters that influenced the enrichment performance such as amount of sorbent, sample pH, type of eluent, volume of eluent, salting-out effect, adsorption time, and desorption time were investigated. Under optimal conditions, excellent linear relationships were found in the concentration range from 0.5 to 100μgL(-1), the limits of detection (S/N = 3) were in the range of 0.26-0.45μgL(-1), and the intra-day and inter-day precisions (n = 6) were in the range of 3.7-4.8 and 3.2-4.3%, respectively. The developed method was evaluated with real water samples, and satisfied spiked recoveries in the range of 99-104% were achieved. The experimental results proved that Fe@SiO2@PEI had good adsorption for phthalate esters, and would be a good adsorbent for the magnetic solid-phase extraction of important pollutants from environmental water samples.ᅟ Graphical abstract A flowchart of the synthesis of polyethyleneimine grafted silica coated nanoscale zero valent iron (Fe@SiO2@PEI) and the process of the developed magnetic solid phase extraction of phthalate esters before the analysis by high performance liquid chromatography.

Ultrasound-assisted low density solvent based dispersive liquid-liquid microextraction for determination of phthalate esters in bottled water samples

A technique of ultrasound-assisted low density solvent based dispersive liquid-liquid microextraction was developed for the determination of four phthalate esters, including dimethyl phthalate(DMP), diethyl phthalate(DEP), di-n-butyl phthalate(DnBP) and di(2-ethylhexyl) phthalate(DEHP) in bottled water samples. A low density solvent, toluene, was selected as extraction solvent. In the extraction process, a mixture of 15 μL of toluene(extraction solvent) and 100 μL of methanol(disperser solvent) was rapidly injected into 1.0 mL of water samples. A cloudy solution was formed after ultrasounded for 5 min, and then centrifuged at 5000 r/min for 5 min. The enriched analytes in the floating phase were determined by means of gas chromatograph. Under the optimum conditions, the enrichment factors were found to be in a range of 29―67, and the recoveries were ranged from 81.2% to 103.9%. The limits of the detection were in a range of 3.8―5.6 μg/L. The proposed method was applied to the extraction and determination of phthalate esters in bottled water samples, and the concentrations of phthalate esters found in the water samples were below the allowable levels.

Determination of phthalate esters in teas and tea infusions by gas chromatography–mass spectrometry

Phthalate esters (PAEs), a group of environmental pollutants which are carcinogenic to human body, have been detected in teas. In this work, five PAEs in teas and tea infusions were quantitatively determined by a modified simultaneous distillation extraction (SDE) coupled with gas chromatography–mass spectrometry. After the optimization of SDE, the proposed method afforded a wide range of linearity and high linear regression coefficients with the limits of detection range of 0.24–3.72μg/kg. The average recoveries were 79.83–116.67% for tea samples and 78.22–101.64% for tea infusions with all the relative standard deviations below 20%. The total content of five PAEs in teas was 1.135–3.734mg/kg and the total dissolving ratio of five PAEs from tea to infusion was 19.05–28.07% for the selected tea samples. The risk assessment result of all the selected tea samples demonstrated that the population with the habit of drinking tea won’t cause risk to human health.

Determination of Phthalates in Milk by Ultrasound-Assisted Dispersive Liquid–Liquid Microextraction and Gas Chromatography–Mass Spectrometry

ABSTRACTUltrasound-assisted dispersive liquid–liquid microextraction was coupled with gas chromatography—mass spectrometry for the determination of phthalate esters in milk. Dimethyl phthalate, diethyl phthalate, dibutyl phthalate, benzyl butyl phthalate, bis(2-ethylhexyl) phthalate, and dioctyl phthalate were analyzed in five brands of pasteurized Turkish milk. The efficiencies of the extraction procedure for the analytes were between 66 and 100%. The linear dynamic ranges of the calibration curves were from 0.025 to 1.000 µg/mL with correlation coefficients exceeding 0.99. The precision of the method is acceptable with relative standard deviation values below 5%. Dibutyl phthalate and bis(2-ethylhexyl) phthalate were commonly observed in milk.

Determination of phthalate esters in vegetable oils using direct immersion solid-phase microextraction and fast gas chromatography coupled with triple quadrupole mass spectrometry

Phthalates are a group of synthetic compounds mainly used as plasticizers, which have been classified as endocrine-disrupting chemicals and potential human-cancer causing agents. They can be found in high amounts in foods, deriving mainly from plastic packaging. The analytical determination of these compounds is very challenging since they are ubiquitous. Therefore, minimization of sample manipulation is highly desirable.The present work exploited the application of a solid-phase microextraction method for the analysis of phthalates in vegetable oil. A preliminary comparison between a polydimethylsiloxane (PDMS) and a Carbopack Z/PDMS fiber was carried out both in the headspace and direct immersion extraction modes. Before immersing the fiber, a rapid liquid–liquid extraction was performed using acetonitrile to remove the bulk of triglycerides. PDMS in the direct immersion mode showed the best performance. The method was fully validated obtaining a good linearity with a coefficient of correlation of over 0.9960 for all compounds, repeatability and accuracy values generally better than 10%, and very good limit of quantification values.

Determination of phthalate esters in environmental water by magnetic Zeolitic Imidazolate Framework-8 solid-phase extraction coupled with high-performance liquid chromatography

In this study, the magnetic Zeolitic Imidazolate Framework-8 (ZIF-8) microspheres were successfully synthesized and applied as an effective sorbent for preconcentration of several typical phthalate esters (PAEs) from environmental water samples. Firstly, the solvothermal treatment method was used for preparation of Fe3O4 nanoparticles. Then, mercaptoacetic acid (MAA) was served as the functionalized chemical to modify Fe3O4 nanoparticles. The Fe3O4@ZIF-8 core–shell microspheres were synthesized through coating the MAA-capped Fe3O4 nanoparticles with ZIF-8. By coupling magnetic solid-phase extraction (MSPE) with high-performance liquid chromatography (HPLC), a reliable, sensitive and cost-effective method for simultaneous determination of five main PAEs including dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DBP), benzyl butyl phthalate (BBP), and dioctyl phthalate (DOP) was developed. Good linearity was observed in the range of 1.0–100.0μg/L. The limits of detection (S/N=3) and limits of quantification (S/N=10) were in the range of 0.08–0.24 and 0.3–0.8μg/L, respectively. The relative standard deviations were less than 5.5% and the accuracies of the method for the PAEs were in the range from 85.6% to 103.6%. Finally, the Fe3O4@ZIF-8 was successfully applied for rapid extraction of trace amounts of PAEs in environmental water samples.

Determination of phthalate esters from environmental water samples by micro-solid-phase extraction using TiO2 nanotube arrays before high-performance liquid chromatography.

We describe a highly sensitive micro-solid-phase extraction method for the pre-concentration of six phthalate esters utilizing a TiO2 nanotube array coupled to high-performance liquid chromatography with a variable-wavelength ultraviolet visible detector. The selected phthalate esters included dimethyl phthalate, diethyl phthalate, dibutyl phthalate, butyl benzyl phthalate, bis(2-ethylhexyl)phthalate and dioctyl phthalate. The factors that would affect the enrichment, such as desorption solvent, sample pH, salting-out effect, extraction time and desorption time, were optimized. Under the optimum conditions, the linear range of the proposed method was 0.3-200 μg/L. The limits of detection were 0.04-0.2 μg/L (S/N = 3). The proposed method was successfully applied to the determination of six phthalate esters in water samples and satisfied spiked recoveries were achieved. These results indicated that the proposed method was appropriate for the determination of trace phthalate esters in environmental water samples.

Determination of phthalate esters in Chinese spirits using isotope dilution gas chromatography with tandem mass spectrometry.

Phthalate esters are additives used in polyvinylchloride and are found as contaminants in many food products. An isotope dilution mass spectrometry technique has been developed for accurate analysis of 16 phthalate esters in Chinese spirits by adopting the 16 corresponding isotope-labeled phthalate esters. The ethanol in the spirit sample was first removed by heating with a water bath at 100°C with a stream of nitrogen, after which the residue was extracted with n-hexane twice. The phthalates collected were identified and quantified by gas chromatography with tandem mass spectrometry in multiple reaction monitoring mode. The spiking recoveries of 16 analytes ranged from 94.3 to 105.3% with relative standard deviation values of <6.5%. The detection limits for 16 analytes were <10.0 ng/g. The expanded relative uncertainties were from 3.0 to 14%. A survey was performed on Chinese spirits from the market. Six of the nine analyzed samples were contaminated by phthalates. Di-n-butyl phthalate and di-2-ethylhexyl phthalate showed higher detection frequency and concentrations. This isotope dilution gas chromatography with tandem mass spectrometry method is simple, rapid, accurate, and highly sensitive, which qualifies as a candidate reference method for the determination of phthalates in spirits.

Determination of Phthalate Esters in Liquor by High Resolution Mass Spectrometry

Phthalate esters are environmental hormones present in food due to their migration from packaging materials and other polymers. Gas chromatography and liquid chromatography coupled with mass spectrometry are the most widely used techniques for trace phthalate ester determination. However, a major problem in the analysis is contamination during the sample pretreatment, resulting in false-positive results or over-estimated concentrations. In this study, a simple, rapid, and sensitive method for the determination of seventeen phthalate esters in liquor using high resolution mass spectrometry was developed. Samples were directly analyzed without pretreatment, which reduced contamination and improved the accuracy of the results. In addition, the total time required for the analysis of one sample was only 15 minutes. The method showed good linearity (R2 > 0.995) in the ranges of 1 to 100 µg/L and 100 to 500 µg/L. The limits of detection and quantification were between 0.1 and 1.0 µg/L and 0.4 and 2.0 µg/L, respectively. The precision was evaluated by intra-day and inter-day measurements and expressed as the relative standard deviation (RSD). The values were less than 4.32% and 7.43%, respectively. The recovery values of phthalate esters from liquor fortified at 10, 50, 100, and 200 µg/L were determined to be 88.7% to 119.2%, with relative standard deviations of 0.3% to 9.6% (n = 6). The method was suitable for the rapid screening and confirmation of phthalate esters in liquor.

Determination of phthalate esters in cleaning and personal care products by dispersive liquid–liquid microextraction and liquid chromatography–tandem mass spectrometry

Phthalic acid esters (PEs) were preconcentrated from cleaning products, detergents and cosmetics using ultrasound assisted extraction (UAE) in the presence of acetonitrile, and then submitted to dispersive liquid–liquid microextraction (DLLME). For DLLME, 3mL of acetonitrile extract, 150μL carbon tetrachloride and 10mL aqueous solution were used. The enriched organic phase was evaporated, reconstituted with 25μL acetonitrile and injected into a liquid chromatograph with a mobile phase (acetonitrile:10mM ammonium acetate, pH 4) under gradient elution. Detection was carried out using both diode-array (DAD) and electrospray-ion trap-tandem mass spectrometry (ESI-IT-MS/MS) in the multiple reaction monitoring mode (MRM) of the positive fragment ions. Quantification was carried out using matrix-matched standards. Detection limits were in the range 0.04–0.45ngmL−1 for the six PEs considered. The recoveries obtained were in the 84–124% range, with RSDs lower than 10%. Thirty three different cleaning products were analyzed. The most frequently found compound was diethyl phthalate.

Determination of Phthalate Esters in Wine Using Dispersive Liquid–Liquid Microextraction and Gas Chromatography

A simple and rapid efficient method was developed for the determination of phthalate esters using dispersive liquid–liquid microextraction followed by gas chromatography with flame ionization detection. A mixture of isopropanol (0.75 mL, dispersant) and carbon tetrachloride (30 µL, extractant) with sodium chloride (1%, w/v) was used for extraction. Under optimum conditions, the method provided linear calibration curves between 0.5 and 200 µg L−1 for dibutyl phthalate, and 1.0 and 200 µg L−1 for butyl benzyl phthalate, diethyl phthalate, and diisooctyl phthalate. The relative standard deviations for intra-day and inter-day analyses were less than 5.8% and 6.9%, respectively, with enrichment factors between 229 and 424. Two wine samples were analyzed with recoveries between 70.1% and 119.3%.

Determination of phthalate esters at trace levels in light alcoholic drinks and soft drinks by XAD-2 adsorbent and gas chromatography coupled with ion trap-mass spectrometry detection

An analytical method based on solid phase extraction (SPE) with XAD-2 for the enrichment of seven phthalate esters in light alcoholic drinks (alcohol content below 6% alc vol−1) and in soft drinks has been developed using gas chromatography coupled with an ion-trap mass spectrometer detector (GC/IT-MS). The instrumental analytical protocol was found to yield a linear calibration in the range of 1–800 ng mL−1 with r2 values ≥ 0.912; the limits of detection (LOD) vary between 0.2 pg μL−1 and 20 pg μL−1, whereas the limits of quantification (LOQ) range between 0.6 pg μL−1 and 41 pg μL−1 with relative standard deviations (RSDs) of ≤4.8 and ≤5.5, respectively. The interday precision ranges between 3.6 and 6.3%, whereas the intraday accuracy is between 7.9 and 12.4%. This simple, reliable, reproducible and low-cost analytical method has been applied to several commercial light alcoholic samples such as beers and soft drinks. DEP (0.1–1.0 ng mL−1), DiBP (0.2–2.5 ng mL−1), DBP (1.9–4.4 ng mL−1), BBP (0.08–0.8 ng mL−1), DEHP (3.6–101 ng mL−1) are present in every sample analyzed, whereas DMP (1.9 ng mL−1) and iBcEP (0.08 ng mL−1) are found only in one sample of beer.

Determination of phthalate esters in edible oils by use of QuEChERS coupled with ionic-liquid-based dispersive liquid-liquid microextraction before high-performance liquid chromatography.

A selective and low organic-solvent-consuming method of sample preparation combined with high-performance liquid chromatography with diode-array detection is introduced for analysis of phthalic acid esters in edible oils. Sample treatment involves initial liquid-liquid partitioning with acetonitrile, then QuEChERS cleanup by dispersive solid-phase extraction with primary secondary amine as sorbent. Preconcentration of the analytes is performed by ionic-liquid-based dispersive liquid-liquid microextraction, with the cleaned-up extract as disperser solvent and 1-hexyl-3-methylimidazolium hexafluorophosphate as extraction solvent. Under the optimized conditions, correlation coefficients (r) were 0.998-0.999 and standard errors (S y/x ) were 2.67-3.37 × 10(3) for calibration curves in the range 50-1000 ng g(-1). Detection limits, at a signal-to-noise ratio of 3, ranged from 6 to 9 ng g(-1). Intra-day and inter-day repeatability, expressed as relative standard deviation, were in the ranges 1.0-6.9 % and 2.4-9.4 %, respectively. Recovery varied between 84 % and 106 %. The developed method was successfully used for analysis of the analytes in 28 edible oils. The dibutyl phthalate content of four of the 28 samples (14 %) exceeded the specific migration limit established by domestic and international regulations.

Determination of phthalate esters in liquor samples by vortex‐assisted surfactant‐enhanced‐emulsification liquid–liquid microextraction followed by GC–MS

A novel method using vortex-assisted surfactant-enhanced-emulsification liquid-liquid microextraction has been developed for the extraction of phthalate esters (PAEs) in Chinese liquor samples prior to analysis by GC-MS. In the proposed method, a high-density extraction solvent (carbon tetrachloride) was dispersed into samples with the aid of a surfactant (Triton X-100) and vortex agitation, resulting in a short extraction equilibrium (30 s). After centrifugation, a single microdrop of solvent was easily collected for GC-MS analysis. Key factors that affected the extraction efficiency were optimized. Under the optimum conditions, linearity was found in the range from 0.05 to 50 μg/L. Coefficients of determination varied from 0.9938 to 0.9971. LODs, based on an S/N of 3, ranged from 4.9 to 13 ng/L. Enrichment factors varied from 140 to 184. Reproducibility and recoveries were assessed by testing a series of three liquor samples that were spiked with different concentration levels. Finally, the proposed method was successfully applied to the determination of PAEs in 16 Chinese liquor samples. In this work, high-density-solvent vortex-assisted surfactant-enhanced-emulsification liquid-liquid microextraction was applied for the first time for the extraction of PAEs in Chinese liquor samples and was proved to be simple, rapid, and sensitive.

Determination of phthalate esters in non-alcoholic beverages by GC–MS and optimization of the extraction conditions

A quantificational method for 7 phthalate esters in non-alcoholic beverages was developed. Dimethyl phthalate, di-ethyl phthalate, di-propyl phthalate (DPP), di-butyl phthalate (DBP), benzyl butyl phthalate, di-(2-ethylhexyl) phthalate (DEHP), and di-octyl phthalate (DOP) were extracted from non-alcoholic beverages with the optimized solid-phase extraction method, and quantification was achieved by gas chromatography–mass spectrometry with isotope internal standard of d4-di-(2-ethylhexyl) phthalate (DEHP-d4). The inter-day method repeatability (RSD) was 8–13 %, whereas the intra-day method repeatability (RSD) was 9–15 %. The mean spiking recoveries were 84–105 %. A wide variety of phthalate concentrations was observed in 48 non-alcoholic beverages. DEHP was the most abundant phthalate compound followed by DBP, DPP, and DOP. DEHP was found in sport drinks (0.015–0.098 mg L−1), tea (0.016–0.123 mg L−1), coffee (0.028–0.159 mg L−1), and fruit juices (0.022–0.126 mg L−1).

Determination of phthalate esters in bottled water using dispersive liquid–liquid microextraction coupled with GC–MS

Dispersive liquid-liquid microextraction method was developed for the determination of the amount of phthalate esters in bottled drinking water samples and dispersive liquid-liquid microextraction samples were analyzed by GC-MS. Various experimental conditions influencing the extraction were optimized. Under the optimized conditions, very good linearity was observed for all analytes in a range between 0.05 and 150 μg/L with coefficient of determination (R²) between 0.995 and 0.999. The LODs based on S/N = 3 were 0.005-0.22 μg/L. The reproducibility of dispersive liquid-liquid microextraction was evaluated. The RSDs were 1.3-5.2% (n = 3). The concentrations of phthalates were determined in bottled samples available in half shell. To understand the leaching profile of these phthalates from bottled water, bottles were exposed to direct sunlight during summer (temperature from 34-57°C) and sampled at different intervals. Result showed that the proposed dispersive liquid-liquid microextraction is suitable for rapid determination of phthalates in bottled water and di-n-butyl, butyl benzyl, and bis-2-ethylhexyl phthalate compounds leaching from bottles up to 36 h. Thereafter, degradation of phthalates was observed.

Determination of Phthalate Esters in Wastewater by Single-Drop Microextraction Coupled to Capillary Gas Chromatography

Single-drop microextraction (SDME) coupled to capillary gas chromatography (GC) was established for the determination of four phthalate esters in wastewater, including dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-octyl phthalate (DnOP) and butyl benzyl phthalate (BBP). The SDME parameters such as extractants, extracting time，stirring rate and immerging depth of needle point were studyed and optimized. The abovementioned phthalate esters were quantified by external standardization method using GC coupled with a flame ionization detector (FID). The linear regression calibration curves, detection limits (S/N=3) and the linear ranges of the method for determining each phthalate were determined, respectively. The concentrations of components abovementioned in a real wastewater sample, the average of the recoveries obtained in the spiked wastewater samples and the corresponding relative standard deviations were determined, respectively. The results showed the proposed method several attributes, friendly enviroment, economic and highly efficient pretreatment, less time, simplicity, sensitivity, accuracy and wide linear range and so on.

Rapid Determination of 15 Kinds of Phthalate Esters in Vegetable Juices by Hollow Fiber-Liquid Phase Microextraction Coupled with Gas Chromatography-Mass Spectrometry

A method has been developed for the simultaneous determination of 15 phthalate esters in vegetable juices by hollow fiber-liquid phase microextraction coupled with gas chromatography-mass spectrometry.The variable experimental conditions such as extraction organic solvent,extraction time,and frequency of agitation were studied.Under the conditions of room temperature(23 ℃),fast speed of agitation frequency,extraction time with 50 min,and hexane as the extraction solvent,the extraction efficiency was higher.After extraction,1 μL organic solvent was injected into GC-MS(EI) with column DB-5(30 m × 0.25 mm × 0.25 μm).Under the conditions,concentration factors of 15 phthalate esters were 4.2-315.6,limit of detection were 0.0001-0.01 mg/L,the recoveries were 71.8%-90.1%,and the relative standard deviations were 2.1%-18.9%.The method is fast and has high sensitivity for the determination of phthalate esters in vegetable juices.

On-line heat-assisted push/pull perfusion hollow fiber liquid–liquid–liquid microextraction for the rapid determination of phthalate esters in river water samples

In this study, we evaluated three advanced effects of push/pull perfusion (PPP) and heat on the extraction efficiencies of neutral analytes, following on from previous studies in which we employed on-line sample cleanup and enrichment—combining PPP and ultrasonication with hollow-fiber liquid–liquid–liquid microextraction (HF-LLLME)—for the extraction of acidic phenols from aqueous samples. First, we observed acceptor phase fluid loss or gain occurring in the push-only perfusion-based and pull-only perfusion-based HF-LLLME modes, but not in the PPP mode. Second, we found that heating is a simple technique for improving the extraction kinetics of model neutral compounds (low-molecular-weight phthalates, LPAEs) when using PPP-assisted HF-LLLME. Third, the time required for extraction of these LPAEs through on-line heat-assisted PPP HF-LLLME decreased by as much as 86% relative to that required for conventional off-line HF-LLLME. From an investigation of the factors affecting the heat-assisted PPP HF-LLLME of LPAEs, we established optimal extraction conditions with a sampling time of just 4 min, providing enrichment factors in the range 171–199.