Extraction Of Phthalate Esters Research Articles

Quinoline Bridging Hyperconjugated Covalent Organic Framework as Solid-Phase Microextraction Coating for Ultrasensitive Determination of Phthalate Esters in Water Samples.

Phthalate esters (PAEs) are widely distributed in the environment, and this has caused serious health and safety concerns. Development of rapid and ultrasensitive identification and analysis methods for phthalate esters is urgent and highly desirable. In this work, a novel nitrogen-rich covalent organic framework (N-TTI) derived quinoline bridging covalent organic framework (N-QTTI) was fabricated and used as a solid-phase microextraction (SPME) coating for the ultrasensitive determination of phthalate esters in water samples. The physical and chemical properties of N-QTTI were investigated sufficiently. The N-QTTI-coated fiber demonstrates a superior enrichment performance than either the N-TTI-coated fiber or commercial fibers under the optimized SPME conditions. For the first time, we propose a semi-immersion strategy for the extraction of PAEs from water samples based on N-QTTI-coated SPME fibers. Combined with gas chromatography-mass spectrometry (GC-MS), the developed method N-QTTI-SPME-GC-MS exhibits a wide linear range with a satisfactory linearity (R2 ≥ 0.995). The limits of detection (LOD, S/N = 3) and the limits of quantification (LOQs, S/N = 10) were 0.17-1.70 and 0.57-5.60 ng L-1, respectively. The repeatability of the new method was examined using relative standard deviations (RSDs) between intraday and interday data, which were 0.38-7.98% and 1.22-6.60%, respectively. The spiked recoveries at three levels of 10, 100, and 1000 ng L-1 were in the range of 90.0-106.2% with RSDs of less than 7.48%. The enrichment factors ranged from 291 to 17180. When compared to previously published works, the LODs of the newly established method were improved 5-5400 times, and the enrichment factors were increased by at least 8 times. The absorption mechanism was investigated by X-ray photoelectron spectroscopy and noncovalent interaction force analysis. The technique was successfully employed for detecting PAEs in water samples.

Copper ferrite nanoparticles as novel coating appropriated to solid-phase microextraction of phthalate esters from aqueous matrices

The prepared CuFe2O4 nanoparticles (NPs) resulting from a facile citrate–nitrate combustion method were adhesived on stainless steel wire with epoxy glue as a novel fiber coating. A direct immersion solid-phase microextraction (DI-SPME) method based on the prepared coating was established through sensitively detecting four phthalate esters (PAEs) from aqueous media with gas chromatography-flame ionization detection (GC-FID). The effects of various parameters on the efficiency of SPME process such as extraction time, extraction temperature, pH, ionic strength, desorption time, and desorption temperature were studied. Under optimized conditions, the limit of detections (LODs) and quantifications (LOQs) for the phthalate esters varied in the range of 0.12–0.40 μg·L−1 and 0.40–1.33 μg·L−1, respectively. The inter-day and intra-day relative standard deviations for these varied phthalate esters at 10 μg·L−1 concentration level (n = 6) using a single fiber were 3.9–12.4% and 6.6–15.1%, respectively. The fiber to fiber repeatabilities (n = 3), expressed as relative standard deviation (RSD%), were between 9.9% and 16.5% at 10 μg·L−1 concentration levell, and the the linear ranges varied between 1 and 500 μg·L−1. The prepared fiber can be repeatedly used to exceed 80 times, revealing a long lifetime and good stability. The method was successfully applied to analysis of the mineral water samples with recoveries from 81.1 to 103.7%. This work also provided an interesting insight for stable SPME fiber prepared by spinel materials for efficient extraction of PAEs.

Detection of phthalate esters in PET bottled drinks and lake water using esterase/PANI/CNT/CuNP based electrochemical biosensor

Phthalate esters (PEs) are the most common plasticizers that tends to exhibit endocrine disruption. Since, these PEs are used in the manufacture of PET bottles and PVC products: point of exposure magnifies up on consumption of PET bottle and plastic container stored drinking water and beverages. Apart from human exposure to PEs, bioaccumulation of PEs and toxic effects among wildlife also seems to be divergent. In the present study, an enzyme-based biosensor for the detection of PEs was developed to overcome the tedious extraction procedures involving PE extraction and sophisticated instruments for the detection. Linear Sweep voltammetry analysis of Nafion (NF) surface modified glassy carbon electrode with esterase (EST) and nano-components was carried-out. Peak potential of individual PEs were in the range of −1.72 to −1.82 V at the concentration of 1 × 10−5 mmol L−1. Sensitivity of EST/PANI/CNT/CuNP–NF modified GCE was determined in terms of detection limit and was calibrated to be 0.03–0.08 nmol L−1. Thus, the developed enzyme based electrochemical sensor could be successfully employed in determining PE exposure in humans and bioaccumulation among aquatic flora and fauna via., consumption of PET bottle stored drinks and industrial effluents discharged into the lakes.

Determination of 11 Phthalate Esters in Beverages by Magnetic Solid-Phase Extraction Combined with High-Performance Liquid Chromatography

Abstract Background: Beverages can be easily contaminated by phthalate esters (PAEs) during the production, bottling, and transportation processes. It is necessary to determine the contamination level in beverages for assessment of human exposure. Objective: In this study, magnetic solid-phase extraction (MSPE) was combined with HPLC for the determination of 11 PAEs in beverages. Methods: Self-synthesized magnetic multiwalled carbon nanotubes (m-MWCNTs) were used as the adsorbent for PAE extraction. To extract the PAEs, an appropriate amount of m-MWCNTs and NaCl was added to the beverage sample. The mixture was mixed on a vortex mixer, the magnetic sorbent was collected with the aid of a magnet, and the supernatant was removed. Then, the analytes were eluted with n-hexane–acetone (1+1, v/v). Finally, the eluent was analyzed by the HPLC method. The separation was accomplished on a Phenomenex Luna-C18 column (250 × 4.6 mm, 5 μm), and the detection wavelength was set at 225 nm. Results: The linear ranges of the method were 2–300 μg/L with correlation coefficients greater than 0.9981. The LOD and LOQ were in the range of 0.659–5.33 × 10–2 μg/L and 2.20–17.8 × 10–2 μg/L, respectively. The recoveries of the method ranged from 79.8 to 114%, with the relative SDs less than 15.8%. The established method has been successfully applied for the determination of 11 PAEs in mineral water, carbonated soft drink, tea beverage, and fruit juice samples. PAEs were detected at 0.246–34.3 μg/L in these samples. Conclusions: The m-MWCNTs are the satisfactory sorbent for MSPE because of their strong adsorption capacity for PAEs. The established MSPE-HPLC method is rapid, easy, sensitive, green, and cost-effective. It can be applied to the analysis of trace PAEs in plastic bottled beverages. Highlights: Three magnetic nanoparticles (MNPs), including Fe3O4 MNPs, m-MWCNTs, and magnetic graphene oxide, were synthesized, and m-MWCNTs were chosen as the sorbent of MSPE for PAE extraction because of their strong adsorption capacity for PAEs. An MSPE–HPLC method has been developed for the analysis of 11 phthalates in plastic bottled beverages. The established method was successfully applied to the analysis of 11 phthalates in four types of beverage samples.

Preconcentration/Extraction of Phthalate Esters in Milk Samples Using MFe2O4-Based Magnetic Ionic Liquid Effervescent Tablets Consisting of Accessory Functional Fillers

Magnetic effervescent tablet-based (MEFTs) microextraction has recently gained much attention because it requires no physical energy inputs or dispersive solvent. A prominent shortcoming of MEFTs results from the short tablet storage period owing to rapid absorption of moisture, thereby making it impracticable for field use. Physico-chemical properties of MEFTs were greatly improved by the addition of water-soluble starch, such as hygroscopicity, storage/stability period, adherence, effervescent time, and intensity. MEFTs were used in a MFe2O4-based magnetic ionic liquid effervescent tablet microextraction (MMIL-ETM) for preconcentration/extraction of trace phthalate esters (PAEs) in milk matrices. This MMIL-ETM method provided three distinct advantages: (1) MEFTs integrate water-soluble starch as a functional filler, leading to longer tablet storage/stability; (2) combined effervescent dispersion and rapid retrieval of NiFe2O4 magnetic nanoparticles (MNPs) result in substantial time saving; and (3) integration of ionic liquid-based extraction with MNP adsorption produces high PAEs extraction recoveries. Optimized experimental parameters were as follows: 0.77 g mixture of Na2CO3 and water-soluble starch, 7 mg NiFe2O4 (30 nm), 50 μL [HMIM]NTf2, solution pH 2.3, and 300 μL acetonitrile as elution solvent. Under optimized conditions, extraction recoveries for four PAEs reached as high as 94.8–105.6%, LODs were as low as 0.042 μg L−1, and RSDs were < 5.4% for intra- and inter-day precisions. Due to the longer stable storage period and rapid dispersion without additional physical energy inputs, the proposed MMIL-ETM method shows great potential application for routine food monitoring under field conditions.

Determination of 11 Phthalate Esters in Beverages by Magnetic Solid-Phase Extraction Combined with High-Performance Liquid Chromatography.

Background: Beverages can be easily contaminated by phthalate esters (PAEs) during the production, bottling, and transportation processes. It is necessary to determine the contamination level in beverages for assessment of human exposure. Objective: In this study, magnetic solid-phase extraction (MSPE) was combined with HPLC for the determination of 11 PAEs in beverages. Methods: Self-synthesized magnetic multiwalled carbon nanotubes (m-MWCNTs) were used as the adsorbent for PAE extraction. To extract the PAEs, an appropriate amount of m-MWCNTs and NaCl was added to the beverage sample. The mixture was mixed on a vortex mixer, the magnetic sorbent was collected with the aid of a magnet, and the supernatant was removed. Then, the analytes were eluted with n-hexane-acetone (1+1, v/v). Finally, the eluent was analyzed by the HPLC method. The separation was accomplished on a Phenomenex Luna-C18 column (250 × 4.6 mm, 5 μm), and the detection wavelength was set at 225 nm. Results: The linear ranges of the method were 2-300 μg/L with correlation coefficients greater than 0.9981. The LOD and LOQ were in the range of 0.659-5.33 × 10-2 μg/L and 2.20-17.8 × 10-2 μg/L, respectively. The recoveries of the method ranged from 79.8 to 114%, with the relative SDs less than 15.8%. The established method has been successfully applied for the determination of 11 PAEs in mineral water, carbonated soft drink, tea beverage, and fruit juice samples. PAEs were detected at 0.246-34.3 μg/L in these samples. Conclusions: The m-MWCNTs are the satisfactory sorbent for MSPE because of their strong adsorption capacity for PAEs. The established MSPE-HPLC method is rapid, easy, sensitive, green, and cost-effective. It can be applied to the analysis of trace PAEs in plastic bottled beverages. Highlights: Three magnetic nanoparticles (MNPs), including Fe₃O₄ MNPs, m-MWCNTs, and magnetic graphene oxide, were synthesized, and m-MWCNTs were chosen as the sorbent of MSPE for PAE extraction because of their strong adsorption capacity for PAEs. An MSPE-HPLC method has been developed for the analysis of 11 phthalates in plastic bottled beverages. The established method was successfully applied to the analysis of 11 phthalates in four types of beverage samples.

A modulation approach for covalent organic frameworks: Application to solid phase microextraction of phthalate esters

A modulation approach with 4-hydroxybenzhydrazide as the modulating agent was designed for constructing 2,4,6-triphenoxy-1,3,5-benzene-based covalent organic frameworks (COFs). The COFs materials were employed as solid phase microextraction (SPME) coatings for the extraction of phthalate esters (PAEs). Various experimental conditions including extraction temperature, extraction time, salt concentration, and desorption time were investigated and optimized. The introduction of modulating agent into the synthesis of fibers significantly enhanced the extraction efficiency towards PAEs. The linear range was 1–100 μg L‒1 and the detection limits in the range of 0.032–0.451 μg L‒1 were achieved with good linearity ranged from 0.9904 to 0.9970. Inter-batch and intra-batch relative standard deviations were in the ranges of 0.83–4.67% and 3.08–9.73%, respectively. Moreover, the developed coating fibers were used for the extraction of PAEs in water samples and satisfactory recoveries were achieved.

Application of non-ionic surfactant as a developed method for the enhancement of two-phase solvent bar microextraction for the simultaneous determination of three phthalate esters from water samples

The extraction of phthalate esters (PEs) from aqueous matrices using two-phase solvent bar microextraction by organic micellar phase was investigated. A short hollow fiber immobilized with reverse micelles of Brij 35 surfactant in 1-octanol was served as the solvent bar for microextraction. Experimental results show that the extraction efficiency were much higher using two-phase solvent bar microextraction based on non-ionic surfactant than conventional two-phase solvent bar microextraction because of a positive effect of surfactant-containing extraction phase in promoting the partition process by non-ionic intermolecular forces such as polar and hydrophobicity interactions. The nature of the extraction solvent, type and concentration of non-ionic surfactant, extraction time, sample pH, temperature, stirring rate and ionic strength were the effecting parameters which optimized to obtain the highest extraction recovery. Analysis of recovered analytes was carried out with high performance liquid chromatography coupled with ultraviolet detection (HPLC–UV). Under the optimum conditions, linearity was observed in the range of 1–800 ng mL−1 for dimethylphthalate (DMP) and 0.5–800 ng mL−1 for diethylphthalate (DEP) and di-n-butyl phthalate (DBP) with correlation determination values above 0.99 for them. The limits of detection and quantification were ranged from 0.012 to 0.03 ng mL−1 and 0.04–0.1 ng mL−1, respectively. The ranges of intra-day and inter-day RSD (n = 3) at 20 ng mL−1 of PEs were 1.8–2.1% and 2.1–2.6%, respectively. Results showed that developed method can be a very powerful, innovative and promising sample preparation technique in PEs analysis from environmental and drinking water samples.

Development and validation of a dispersive liquid-liquid microextraction method for the determination of phthalate esters in perfumes using gas chromatography-mass spectrometry.

A simple, rapid, sensitive and eco-friendly method has been developed for the simultaneous determination, preconcentration and extraction of phthalate esters (dimethyl phthalate, diethyl phthalate, dibutyl phthalate, benzyl butyl phthalate and bis(2-ethylhexyl) phthalate) in perfumes using dispersive liquid–liquid microextraction (DLLME) coupled to gas chromatography-mass spectrometry (GC-MS). Various factors affecting the DLLME efficiency, including the type and volume of the extracting and dispersing solvents, salt addition and vortex extraction time were optimized. Under optimum conditions, the proposed method provided low detection limits (0.003–0.070 ng mL−1), high extraction recovery (85.6–95.8%), wide linearity range (1.0–1000 ng mL−1) with good regression coefficients (>0.9984) and good precision (RSD% < 4.2%). The optimized method was successfully utilized for the analysis of different branded perfume samples and satisfactory results were obtained.

Electrochemical preparation of zinc oxide/polypyrrole nanocomposite coating for the highly effective solid-phase microextraction of phthalate esters.

In this work, zinc oxide/polypyrrole nanocomposite coating was fabricated on stainless steel and evaluated as a novel headspace solid-phase microextraction fiber coating for extraction of ultra-trace amounts of environmental pollutants, namely, phthalate esters, in water samples. The fiber nanocomposite were prepared by a two-step process including the electrochemical deposition of polypyrrole on the surface of stainless steel in the first step, and electrochemical deposition of zinc oxide nanosheets in the second step. Porous structure together with zinc oxide nanosheets with the average diameter of 30nm were observed on the surface by using scanning electron microscopy. The effective parameters on extraction of phthalate esters (i.e., extraction temperature, extraction time, desorption temperature, desorption time, salt concentration, and stirring rate) were investigated and optimized by one-variable-at-a-time method. Under optimized conditions (extraction temperature, 90°C; extraction time, 40min; desorption temperature, 270°C; desorption time, 5min; salt concentration, 25% w/v; and stirring rate, 1000rpm), the limits of detection were in the range of 0.05-0.8μg/L, and the repeatability and fiber-to-fiber reproducibility were in the ranges of 6.1-7.3% and 8.7-10.2%, respectively.

Ionic liquid enhanced magnetic solid-phase extraction of phthalate esters in food samples with oleic acid coated-Fe3O4 nanoparticles prior to HPLC

ABSTRACTA novel method based on ionic liquid enhanced magnetic solid-phase extraction (MSPE) coupled with high-performance liquid chromatography (HPLC) for the separation/analysis of phthalate esters (PAEs) in food samples was established. 1-hexyl-3-methylimidazoliu-hexafluorophosphate ([C6MIM][PF6]) was used to coat oleic acid Fe3O4 nanoparticles with core–shell structures to prepare MSPE agents (Fe3O4@OA@IL). The main parameters affecting the extraction efficiency of PAEs were studied. Under the optimal conditions, the calibration curves were linear in the range of 5–5000 ng mL−1 (R2 = 0.9972–0.9998) of four PAEs. The limit of detections (LODs) and relative standard deviations (RSDs, n = 5) of the method were 1.27–2.95 ng mL−1 and 3.9–5.3%, respectively.

Magnetic N-doped mesoporous carbon as an adsorbent for the magnetic solid-phase extraction of phthalate esters from soft drinks.

A new kind of magnetic N-doped mesoporous carbon was prepared by the one-step carbonization of a hybrid precursor (glucose, melamine, and iron chloride) in a N2 atmosphere with a eutectic salt (KCl/ZnCl2 ) as the porogen. The obtained magnetic N-doped mesoporous carbon showed excellent characteristics, such as strong magnetic response, high surface area, large pore volume, and abundant π-electron system, which endow it with a great potential as a magnetic solid-phase extraction adsorbent. To evaluate its adsorption performance, the magnetic N-doped mesoporous carbon was used for the extraction of three phthalate esters from soft drink samples followed by high-performance liquid chromatographic analysis. Under the optimum conditions, the developed method showed a good linearity (1.0-120.0ng/mL), low limit of detection (0.1-0.3ng/mL, S/N = 3), and good recoveries (83.2-119.0%) in soft drink samples. The results indicated that the magnetic N-doped mesoporous carbon has an excellent adsorption capacity for phthalate esters and the present method is simple, accurate, and highly efficient for the extraction and determination of phthalate esters in complex matrix samples.

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.

Direct Extraction of Phthalate Esters from Polymeric Gloves Materials

Phthalate esters (PAEs) have been widely added as the plasticizer to increase the flexibility and ductility of polymeric materials. In this study, organic solvents, such as methanol, hexane, ethyl ether and acetone, were used for the direct extraction of plasticizers in neoprene, nitrile, and PVC gloves, under a temperature range of 20-80°C. The results showed that DEHP (Di-2-ethylhexyl phthalate) and DBP (Di-n-butyl phthalate) were analyzed in all three glove samples. The extraction capability of PAEs from the PVC gloves was the highest, while that from the neoprene gloves was the lowest. It was found that the extraction capabilities of DEHP from the glove samples were proportional to Log Kow of the extraction solvents. This result implied that PAEs were more soluble in a non-polar solvent and likely to be extracted from the glove samples. In addition, the amount of extracted PAEs increased with the experimental temperatures. As workers wearing the chemical protective gloves, there is a need to understand the dissolution potential of PAEs in the gloves and to assess the skin exposure of PAEs.

Study of menthol as a green extractant in dispersive liquid–liquid microextraction; application in extraction of phthalate esters from pharmaceutical products

A new mode of dispersive liquid–liquid microextraction performed in a narrow-bore glass tube has been developed for the extraction/preconcentration of some phthalate esters (EFs) in pharmaceutical samples. For the first time, menthol was used as the green extraction solvent in DLLME. Menthol (mg-level) was dissolved in a disperser solvent and injected into the aqueous sample solution placed in the tube (from the bottom side). Menthol fine droplets containing the extracted and preconcentrated analytes were collected on top of the tube in less than 5 min, and rapidly solidified by contact with air and formed a single solid piece. The solidified menthol was transferred into a vial with a conical bottom and dissolved in acetone (μL-level). Finally 1 μL of the solution was injected into gas chromatography-flame ionization detection for analysis of the extracted analytes. Five PEs e.g. di-methyl phthalate (DMF), di-ethyl phthalate (DEP), di-iso butyl phthalate (DIBP), di-n-butyl phthalate (DNBP), and di-iso octyl phthalate (DIOP) were selected as model analytes for evaluating the method. The influence of important parameters on the extraction efficiency were investigated in detail and optimized. Under the optimum experimental conditions, the method showed good linearities (R2 > 0.996), and broad linear ranges (10–10 000 μg L−1). Limits of detection were in the range of 1–8 μg L−1. The proposed method was applied on some pharmaceutical samples, and the obtained results were compared with those of some conventional methods, and revealed that this method has higher extraction efficiency. This technique is environmentally-friendly, affordable, efficient and convenient for sample preparation, with no need for centrifuging; making it fast and simple.

Low-density solvent-based vortex-assisted surfactant-enhanced-emulsification liquid–liquid microextraction combined with gas chromatography–mass spectrometry for the fast determination of phthalate esters in bottled water

For the first time, a novel low-density solvent-based vortex-assisted surfactant-enhanced-emulsification liquid–liquid microextraction (LDS–VSLLME) was developed for the fast, simple and efficient determination of six phthalate esters (PEs) in bottled water samples followed by gas chromatography–mass spectrometry (GC–MS). In the extraction procedure, the aqueous sample solution was injected into a mixture of extraction solvent (toluene) and surfactant (cetyltrimethyl ammonium bromide), which were placed in a glass tube with conical bottom, to form an emulsion by the assistance of vortex agitation. After extraction and phase separation by centrifugation, and removal of the spent sample, the toluene extract was collected and analyzed by GC–MS. The addition of surfactant enhanced the dispersion of extraction solvent in aqueous sample and was also favorable for the mass transfer of the analytes from the aqueous sample to the extraction solvent. Moreover, using a relatively less toxic surfactant as the emulsifier agent overcame the disadvantages of traditional organic dispersive solvents that are usually highly toxic and expensive and might conceivably decrease extraction efficiency to some extent since they are not as effective as surfactants themselves in generating an emulsion. With the aid of surfactant and vortex agitation to achieve good organic extraction solvent dispersion, extraction equilibrium was achieved within 1min, indicating it was a fast sample preparation technique. Another prominent feature of the method was the simple procedure to collect a less dense than water solvent by a microsyringe. After extraction and phase separation, the aqueous sample was removed using a 5-mL syringe, thus leaving behind the extract, which was retrieved easily. This novel method simplifies the use of low-density solvents in DLLME. Under the optimized conditions, the proposed method provided good linearity in the range of 0.05–25μg/L, low limits of detection (8–25ng/L) and good enrichment factors up to 290. The proposed method was successfully applied to the extraction of PEs in bottled water samples as a fast, efficient, and convenient method.

Extraction of Phthalate Esters in Environmental Water Samples Using Layered-Carbon Magnetic Hybrid Material as Adsorbent Followed by Their Determination with HPLC

) hybrid material was synthesized through a facile one-potsolvothermal method and used as the adsorbent for the preconcentration of some phthalate esters (dimethylphthalate, diethyl phthalate, diallyl phthalate, diisobutyl phthalate and benzyl butyl phthalate) in water samples.The effects of the adsorbent dosage, extraction time, the solution pH and salinity on the adsorption of thephthalate esters (PAEs) were investigated. The magnetic nanocomposite adsorbent could remove and enrichthe PAEs from water samples efficiently. After the adsorption, the analytes were desorbed and then determinedby high performance liquid chromatography-ultraviolet detection. Under the optimum conditions, theenrichment factors of the method for the analytes were in the range from 161 to 180. A linear response withpeak area as the quantification signal was observed in the concentration range from 0.5 to 100 ng mL

Determination of phthalate esters in cow milk samples using dispersive liquid‐liquid microextraction coupled with gas chromatography followed by flame ionization and mass spectrometric detection

A simple and economic method for the analysis of phthalate esters, dimethyl phthalate, diethyl phthalate, di-iso-butyl phthalate, di-n-butyl phthalate, and di-2-ethylhexyl phthalate in cow milk samples by means of gas chromatography-flame ionization detection and gas chromatography-mass spectrometry has been developed. In this work, NaCl and ACN were added to 5 mL of the milk sample as the salting out agent and extraction solvent, respectively. After manual shaking, the mixture was centrifuged. In the presence of NaCl, a two-phase system was formed: upper phase - acetonitrile containing phthalate esters -and lower phase - aqueous phase containing soluble compounds and the precipitated proteins. After the extraction of phthalate esters from milk, a portion of supernatant phase (acetonitrile) was removed, mixed with 1,2-dibromoethane at microliter level and injected by syringe into NaCl solution. After the extraction of the selected phthalate esters into 1,2-dibromoethane, phase separation was performed by centrifugation and the enriched analytes in the sedimented phase were determined by gas chromatography-flame ionization detection and gas chromatography-mass spectrometry. Under the optimum extraction conditions, low limits of detection and quantification between 1.5-3 and 2.5-11 ng/mL, respectively was observed. Enrichment factors were in the range of 397-499. The relative standard deviations for the extraction of 100 ng/mL of each phthalate ester were in the range of 3-4% (n = 6). Finally, some milk samples were successfully analyzed using the proposed method and two analytes, di-n-butyl phthalate and di-2-ethylhyxel phthalate, were determined in them in nanogram per milliliter level.

Extraction of phthalate esters from water and beverages using a graphene-based magnetic nanocomposite prior to their determination by HPLC

We have developed a highly sensitive microextraction method for the preconcentration of some phthalate esters such as diethyl phthalate, di-n-propylphthalate, di-n-butyl-phthalate, dicyclohexyl-phthalate, and diethyl-hexyl phthalate prior to their determination by HPLC. It is based on a magnetic graphene nanocomposite as an effective adsorbent. The effects of the amount of the extractant composite employed, extraction time, pH values, salt concentration and desorption conditions were investigated. Under the optimum conditions, the enrichment factors range from 1574 to 2880. Response is linear in the concentration range from 0.1 to 50 ng mL−1. The limits of detection (at S/N = 3) were between 0.01 and 0.04 ng mL−1. The method was successfully applied to the determination of five phthalate esters in water and beverage samples.

Thermal Immobilization of Poly(Butylacrylate) on Glass-Ceramic Rod for Preparation of Solid Phase Microextraction Fibers

The efficiency of a glass-ceramic rod as a base for the preparation of SPME fibers using thermal immobilization was investigated. Glass-ceramic and fused silica rods were thermally immobilized with poly(butylacrylate) and their absorption capacity was compared. The absorption capacity between the fiber obtained for thermal immobilization of poly(butylacrylate) on glass-ceramic surface and commercially PA fiber was also compared. In this study the target analytes were phthalate esters and phenols. The results obtained for extraction of phenols from aqueous solutions using the headspace mode demonstrated the superiority of glass-ceramic in relation the silica gel rod as a base for SPME fiber. The direct SPME extraction of phthalate esters from aqueous solutions using commercial PA fiber and that obtained for thermal immobilization of poly(butylacrylate) on glass-ceramic rod presented similar results. The repeatability and the reproducibility among extractions using fibers developed in our laboratory were achieved.