Dimethyl Phthalate Research Articles

Brønsted-acid sites promoted degradation of phthalate esters over MnO2: Mineralization enhancement and aquatic toxicity assessment

Advanced oxidation processes (AOPs) are important technologies for aqueous organics removal. Despite organic pollutants can be degraded via AOPs generally, high mineralization of them is hard to achieve. Herein, we synthesized a manganese oxide nanomaterial (H2-OMS-2) with abundant Brønsted-acid sites via ion-exchange of cryptomelane-type MnO2 (OMS-2), and tested its catalytic performance for the degradation of phthalate esters via peroxymonosulfate (PMS) activation. About 99% of dimethyl phthalate (DMP) at a concentration of 20 mg/L could be degraded within 90 min and 82% of it could be mineralized within 180 min over 0.6 g/L of catalyst and 1.8 g/L of PMS. The catalyst could activate PMS to generate SO4−˙ and ·OH as the dominant reactive oxygen species to reach complete degradation of DMP. Especially, the higher TOC removal rate was obtained due to the rich Brønsted-acid sites and surface oxygen vacancies on the catalyst. Kinetics and mechanism study showed that MnII/MnIII might work as the active sites during the catalytic process with a lower reaction energy barrier of 55.61 kJ/mol. Furthermore, the catalyst could be reused for many times through the regeneration of the catalytic ability. The degradation and TOC removal efficiencies were still above 98% and 65% after seven consecutive cycles, respectively. Finally, H2-OMS-2-catalyzed AOPs significantly reduced the organismal developmental toxicity of the DMP wastewater through the investigation of zebrafish model system. The present work, for the first time, provides an idea for promoting the oxidative degradation and mineralization efficiencies of aqueous organic pollutants by surface acid-modification on the catalysts.

Occurrence, spatial distribution and ecological risk assessment of phthalate esters in water, soil and sediment from Yangtze River Delta, China

A total of 96 water, soil, and sediment samples, collected from 32 sampling sites in the Yangtze River Delta (YRD) region, were analyzed for 9 phthalate esters (PAEs). The sum concentrations of 9 PAEs (∑9PAEs) in the water, soil, and sediment samples were 2.23–6.30 μg L−1 (mean: 4.11 μg L−1), 155–1410 μg kg−1 (408 μg kg−1), and 30.1–16,000 μg kg−1 (1200 μg kg−1), respectively. Among the 9 PAEs, di-n-butyl phthalate (DBP), bis(2-ethylhexyl) phthalate (DEHP), and di-isobutyl phthalate (DIBP) are the predominant congeners in the YRD region. DBP was the dominant PAE congener in water, accounting for 50.6% of the Σ9PAEs, while DEHP was the predominant one in soil and sediment (accounting for 69.6% and 83.1% of the Σ9PAEs, respectively). Soil and sediment samples collected from Wuxi city manifested relatively higher PAE concentrations. The partitioning of PAEs between water and sediment was attributed to the fact that low molecular weight PAEs (e.g., dimethyl phthalate (DMP) and diethyl phthalate (DEP)) were dominant in water, medium molecular weight PAEs (e.g., BzBP) were close to the equilibrium between sediment–water, and high molecular weight PAEs (e.g., DEHP) were more prevalent in sediment. The ecological risk assessment of PAEs in the surface water showed that the potential environmental risks followed the order of DEHP > DIBP > DBP > DMP > DEP. Comparatively, DEHP posed high ecological risk to sensitive algae, crustaceans and fish, while DMP and DEP exhibited low risk. In the sediment, DIBP exhibited a high risk to the sensitive fish, whereas DMP, DEP, DBP and DEHP displayed no risk.

Ecotoxicological and genotoxic effects of dimethyl phthalate (DMP) on Lemna minor L. and Spirodela polyrhiza (L.) Schleid. plants under a short-term laboratory assay

The environmental occurrence of phthalates (PAE) is of great concern for the ecosystem and human health. Despite of their recognized toxicity on biota, a lack of knowledge is still present about the effects of PAE on plants. In this scenario, the effects of dimethyl phthalate (DMP) on duckweed plants (Lemna minor L. and Spirodela polyrhiza (L.) Schleid.), two model plant species for ecotoxicological and trophic studies, were investigated. Under a 7-day lab assay, morphological (biometric indicators), physiological (pigment content and photosynthetic performance) and molecular (DNA damage) parameters were studied. No effects were observed at growth and physiological level in both plants at 3 and 30 mg/L DMP. On the contrary, at 600 mg/L DMP, a concentration used for plant acute toxicity studies, a remarkable growth inhibition and pigment content and photosynthetic parameters reduction compared to control were observed in both plants species, particularly in Spirodela. Alkaline Comet assay in 24 h-treated plants revealed a genotoxic damage induced by DMP, particularly relevant in Spirodela. These results described for the first time the adverse effects exerted by DMP on aquatic plants, contributing to highlight the environmental risk associated to the presence of this compound in the aquatic ecosystem.

Metrological support of phthalate content measurements: reference material for the composition of a solution of six priority phthalates in methanol

The article provides information on the development of a new reference material (RM) for the composition of a solution of six priority phthalates (dimethyl phthalate, diethyl phthalate, di(n-butyl) phthalate, benzyl butyl phthalate, bis(2-ethylhexyl) phthalate, di(n-octyl) phthalate) in methanol provided with metrological traceability to GET 208-2019 (GET 208). The procedure for the preparation and certification of RMs is shown, including the estimation of homogeneity and stability. Pure organic substances (phthalates) characterized on GET 208 were used as the starting material for the RM. The RM material was prepared by weight and volume-weight methods. The stability study of the RM was carried out by the isochronous procedure. The RM certified values are the mass fraction and mass concentration of individual phthalates in the solution. When calculating the uncertainty budget for RM certified values, contributions from the purity of the starting materials, RM preparation procedures, heterogeneity, and long-term instability were taken into account. The relative expanded uncertainty of the certified values does not exceed 2 %. As a result, a certified reference material (CRM) was developed and approvedfor the composition of a solution of ortho-phthalic acid esters (phthalates) in methanol GSO 11366-2019. The practical significance of the application of GSO 11366-2019 is to ensure the metrological traceability of RM to the corresponding SI units reproduced on GET 208. The developed CRM can be applied in resolving any measuring tasks and performing a full range of metrological works.

Oxidative degradation/mineralization of dimethyl phthalate (DMP) from plastic industrial wastewater using ferrate(VI)/TiO2 under ultraviolet irradiation.

A novel ferrate(VI)/titanium dioxide/ultraviolet [Fe(VI)/TiO2/UV] system was successfully established for the photocatalytic oxidation of dimethyl phthalate (DMP). This system demonstrated a higher removal efficiency of DMP (95.2%) than the conventional TiO2/UV and Fe(VI) alone systems (51.8% and 23.5%, respectively) and produced obvious synergistic effects. Response surface methodology (RSM), based on a three level, three independent variables design, was conducted through Design Expert 8.0.6 program, and a second-order polynomial model (R2 = 0.998) was developed to quantitatively describe the photocatalysis of TiO2 combined with Fe(VI) oxidation under ultraviolet irradiation. The fresh TiO2 and photochemical reacted Fe(VI)/TiO2 were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and element dispersive spectrum (EDS), which indicated that Fe(VI) was imprinted into the TiO2, and the surface adsorbed Fe-O-(organic) materials inhibited DMP degradation. This photocatalytic oxidant showed high activity and stability after nine cycles without loss of its effectiveness (counting from the second cycle). The intermediates/products of DMP were analyzed by gas chromatography-mass spectrometry. The proposed pathway for DMP degradation involved one electron transfer of hydroxyl radical and breaking of the ester bond and benzene ring. The mineralization efficiencies of DMP in actual industrial wastewater and simulated water were 87.1% and 95.2%, respectively, suggesting practical field applications. A ecotoxicity test (17.3% inhibition on bioluminescence) in treating actual industrial wastewater containing DMP implied that the proposed Fe(VI)/TiO2/UV had a potential for industrial water treatment.

Enhancement of the electro-Fenton degradation of organic contaminant by accelerating Fe3+/Fe2+ cycle using hydroxylamine

The Electro-Fenton process can generate reactive oxygen species capable of oxidizing refractory organic contaminants. However, low regeneration efficiency of Fe2+ restricts its application. Herein, hydroxylamine (HA) was added into the Electro-Fenton (HA/Electro-Fenton) process to accelerate the transformation of Fe3+ to Fe2+. Using dimethyl phthalate (DMP) as target contaminant, the HA/Electro-Fenton system alleviated the two-stage reaction process and accelerated the removal of DMP in the pH range of 2.0–6.0. With improving DMP concentration from 5 mg L-1 to 50 mg L-1, their degradation rate increased in the HA/Electro-Fenton system, while decreased in the Electro-Fenton system. The addition of HA had negligible effect on electro-generation of H2O2, but facilitate the redox cycle of Fe3+/Fe2+ and the generation of hydroxyl radicals, thus improving the degradation of DMP. The final transformation products of HA were N2, N2O, and NO3−. The presence of PO43− improved DMP degradation, while Cl− and organic matters inhibited DMP removal in varying degrees. This study provided useful reference to solve the low efficiency of Fe3+/Fe2+ cycle and expand the pH application range in the Electro-Fenton process.

Atmospheric plasma-based approaches for the degradation of dimethyl phthalate (DMP) in water

Cold plasma based treatment of contaminated water is becoming a promising novel green remediation option. This study assessed the performance of two different cold plasma reactors, using, respectively, a self-pulsing discharge (SPD) and a multipin corona discharge (MCD), in the degradation of dimethyl phthalate (DMP), a persistent and ubiquitous pollutant of the aquatic environment. The process kinetics and energy efficiency, as well as the main plasma generated reactive species were determined under various operating conditions concerning the plasma feed gas and flowrate, the voltage polarity, the input power, the DMP initial concentration, the liquid conductivity, and the aqueous matrix used to prepare DMP solutions for these experiments. The MCD reactor, operated with air as plasma feed gas and negative voltage polarity, gave the best results in terms of rate and energy efficiency. Moreover, variations in plasma input power and in the liquid conductivity have limited effect on DMP degradation rate, making this reactor suitable for treating liquids with a range of initial conductivities The effects of DMP initial concentration on its rate of degradation and on the process energy efficiency were also investigated. Differences in the efficiency of production and distribution of plasma generated reactive species, notably •OH and H2O2, observed for the two tested reactors are discussed in terms of different extension of the plasma/liquid interface and diffusion into the bulk solution. It is proposed that among the reactive species, •OH foremost, and O3 to a lesser extent, play a pivotal role in DMP degradation, while the contribution of H2O2 appears to be limited. The rate of DMP degradation was not drastically different in Milli-Q water and in tap water, a positive outcome in view of practical applications of the technology. The lower rate observed in tap than in Milli-Q water is attributed to the presence of bicarbonate and carbonate, which are known scavengers of hydroxyl radicals.

Biodegradation of phthalate esters by Pantoea dispersa BJQ0007 isolated from Baijiu

Baijiu is a famous Chinese alcoholic beverage and is produced by the co-fermentation of microorganisms with grains as the raw materials. Phthalate esters (PAEs) are toxic chemicals and frequently detected in Baijiu. Identification of microorganisms that could degrade PAEs was recognized as a possible way to solve the contamination. Pantoea spp. are one kind of dominant microorganisms for manufacturing Baijiu. Here, Pantoea dispersa BJQ0007 was isolated from Baijiu fermentation starter and showed the ability in degrading dimethyl phthalate, diethyl phthalate, dibutyl phthalate, diisobutyl phthalate, and di-(2-ethylhexyl) phthalate, with di-(2-ethylhexyl) phthalate as the preferred substrate. The whole genome was sequenced with a chromosome of 4,325,134 bp and three plasmids. The metabolic pathway of PAE degradation is proposed with an uncommon metabolic step by converting phthalate monoester to benzoate ester based on metabolic intermediate analysis and genome annotation. Two enzymes responsible for ester bond hydrolysis of PAEs were identified and belonged to enzyme families IV and not defined, respectively. The results revealed PAE degradation of Pantoea species and would promote the safety control of Baijiu products by offering bacterial and enzymatic resources.

Investigating the effectiveness of nanotechnologies in environmental health with an emphasis on environmental health journals

ObjectiveThe use of nanotechnologies is important to reduce environmental health problems in Iran, so the present study was conducted to determine the effectiveness of nanotechnologies in environmental health. This is a cross-sectional descriptive study for 11-year periods (2008–2018) on all articles published in three specialized journals of environmental health with emphasis on the use of nanotechnologies in various fields of environmental health (water, air, sewage, waste, food, radiation, etc).ResultsIn this study, 774 articles related to 114 issues of 3 specialized environmental health journals were reviewed. A review of 774 articles showed that 80 articles (10.3%) were published in the field of nanotechnologies. Out of 80 articles published in the field of nanotechnology, 66 articles (82.5%) were published on the subject of water, 9 articles (11.3%) on wastewater and 5 articles (6.2%) on air pollution. Subject review of articles showed that articles using carbon nanotubes to remove natural organic pollutants, surfactants, hydroxybenzenes, phenol, dimethyl phthalates, use of titanium dioxide nanoparticles, iron-magnesium nanoparticles for wastewater treatment, Silver nanoparticles were used to remove air pollution. The results showed that published articles on nanotechnology in the field of environmental health were few.

Lanthanum/titanium dioxide immobilized onto industrial waste with enhanced photocatalytic activity, and the degradation of dimethyl phthalate

Titanium dioxide (TiO2) is an effective photocatalyst for organic removal. However, its efficacy is hampered by the recombination of photogenerated electrons and holes. This paper presented an eco-friendly, synthetic lanthanum (La)/TiO2 supported on lithium silicon powder (L) to significantly improve photocatalysis. The results showed that 74.4% dimethyl phthalate (DMP) removal was achieved in the ultraviolet (UV)-La-TiO2/L (LTL1) system, which was considerably higher than UV-TiO2/L (TL) (60.1%) and UV-L (18.3%). The enhanced LTL1 photocatalysis was based on the synergic effect between TiO2 and La with L matrix. The photocatalysis efficiency was further improved by hydrogen peroxide (H2O2), while the DMP removal rate reached 100% in the UV-LTL1-H2O2 system. The DMP activation mechanisms and degradation pathways in the UV-LTL1-H2O2 system were carefully examined, revealing that increased hydroxyl free radical (OH•) and superoxide ion radicals (O2−•) were pivotal to the higher degradation rate. Overall, the findings suggested that LTL1 showed considerable application promise for the low-cost and eco-friendly organic removal from water.

Computer assisted preparation and adsorption properties of electrospinning imprinted nanofibers

Dimethyl phthalate (DMP) was used as template molecule to prepare dimethyl phthalate imprinted polymer. The difference of characterization between MINFs and NINFs was analyzed by infrared spectroscopy (FTIR) and scanning electron microscope (SEM). The adsorption performance of imprinted nanofibers was studied through static experiment, isothermal experiment, and selective experiment, respectively. Simultaneously, the nanofibers was applied to analysis for water samples as packing material for solid phase columns. The results of adsorption kinetics showed that MINFs had high sensitivity and selectivity. MINFs showed better binding capacity than NINFs. The maximum binding capacity of MINFs was 4.6×10-2 mmol/g, and that of NINFs was 2.6×10-2 mmol/g. Solid phase extraction (SPE) was used to detect the concentration of DMP in real water samples, the recovery rate reaches 99.45%.

Phthalate esters in face masks and associated inhalation exposure risk

This study assessed the composition of single-use face mask materials, quantified the concentration of phthalate esters in masks and evaluated associated inhalation exposure risk. All the mask samples, including 12 surgical and four N95/P1/P2 masks, were identified to be made of polypropylene, with polyethylene terephthalate present in the N95/P1/P2 masks. Di-methyl phthalate, di-n-butyl phthalate, di-ethyl phthalate, di-isobutyl phthalate and di(2-ethylhexyl) phthalate were frequently detected and their concentration summed up 55 ± 35 ~ 1700 ± 140 ng per surgical mask and 2300 ± 150 ~ 5200 ± 800 ng per N95/P1/P2 mask. Our simulation experiment suggested a mean loss of 13 – 71% of phthalate mass depending on compounds, during 5-hour wearing of these masks. This resulted in an estimated daily intake of individual compounds no higher than 20 ng/kg/day for adults and 120 ng/kg/day for toddlers, which were at least 80 times lower compared to relevant tolerable daily intake values. Two interventional trials were conducted where a volunteer wore a mask for four hours and urine samples were collected before and after the mask wearing. No obvious increase was observed for the urinary concentration of any phthalate metabolite, indicating minimal contribution to overall exposure to phthalate esters.

Enhanced Radical Generation in an Ultraviolet/Chlorine System through the Addition of TiO2.

Ultraviolet (UV)/chlorine draws increasing attention for the abatement of recalcitrant organic pollutants. Herein, it was found that TiO2 would significantly promote the degradation of dimethyl phthalate (DMP) in the UV/chlorine system (from 19 to 84%). Hydroxyl radicals (HO•) and chlorine radicals (Cl•) were the dominant reactive species for DMP degradation in the UV/chlorine/TiO2 system. Chlorine decayed much faster in UV/chlorine/TiO2 compared with UV/chlorine, which is possibly because photogenerated electrons (ecb-) and superoxide radicals (O2•-) have high reactivity with chlorine. As a result, the recombination of photogenerated holes (hvb+) and ecb- was inhibited and the accumulation of HO• and Cl• was facilitated. A kinetic model was established to simulate the reaction process, and it was found that the concentrations of HO• and Cl• were several times to dozens of times higher in UV/chlorine/TiO2 than that in UV/chlorine. The contributions of HO• and Cl• to DMP degradation were 70.3 and 29.7% by model simulation, respectively, and were close to the probe experiment result. In the UV/chlorine/TiO2 system, the degradation of DMP did not follow pseudo-first-order kinetics but the degradation of benzoate fitted well with pseudo-first-order kinetics. This phenomenon was elucidated by the structure of the pollutant and TiO2 and further tested by calculating the adsorption energy (Eads)/binding energy (Eb) with density functional theory. Due to faster decay of chlorine, lower amounts of disinfection byproducts formed in UV/chlorine/TiO2 compared with UV/chlorine. Adding TiO2 into the UV/chlorine system can promote the degradation of recalcitrant organic pollutants in an aqueous environment.

Phthalate esters in surface sediments from fishing ports in Circum-Bohai-Sea region, China

The concentration, composition, distribution, and possible sources of phthalate esters (PAEs) in surface sediments from fishing ports in the Circum-Bohai-Sea region were investigated. The potential ecological risks of PAEs on three sensitive aquatic organisms (algae, crustacean, and fish) were assessed based on the risk quotient. The concentrations of 16 PAEs were in the range of 8.53–86.13 μg/g. Six PAEs, which were considered as priority pollutants by the United States Environmental Protection Agency, were main congeners. Fishing ports with high PAE concentration were located near the eastern area of the Shandong Peninsula, the southern area of the Liaodong Peninsula, and the estuary of the Yellow River. Wastewater, atmospheric deposition, plastic, and rubber products were possible sources of PAEs. The PAEs showed medium to high ecological risks on the three aquatic organisms, and the ecological risks were attributed to four PAEs, including dimethyl phthalate, diethyl phthalate, dibutyl phthalate, and benzylbutyl phthalate.

Associations between phthalic acid esters in household dust and childhood asthma in Shanghai, China

Phthalic acid esters (PAEs) have a negative impact on human health and are widely distributed in China. As part of the China, Children, Home, Health (CCHH) study, we investigated the associations between childhood asthmatic symptoms and PAEs in settled house dust in Shanghai, China.We found that di-2-ethylhexyl phthalate (DEHP), dibutyl phthalate (DBP), and diisobutyl phthalate (DiBP) were abundant in the indoor environment. A total of 27 % of children suffered from diagnosed asthma. The Mann-Whitney U test and multiple logistic regression were used to obtain the associations between PAEs and childhood asthmatic symptoms. Stratification analysis was performed to reveal the influence of gender on the associations between PAE exposure and target symptoms. Compared with low concentrations of PAEs, high concentrations of high molecular weight PAEs (HMW-PAEs) were significantly associated with childhood diagnosed asthma (adjusted odds ratios (AORs) > 1, P < 0.05). Moreover, significantly negative associations were found between high concentrations of DiBP and current cough (AORs<1, P < 0.05). All significantly positive associations were observed among girls, and most of the associations of dimethyl phthalate (DMP) and diethyl phthalate (DEP) exposure with the studied symptoms among girls were higher than those among boys. Exposure to PAEs may be a risk factor for asthmatic symptoms in children, especially in girls.

Enhanced photocatalytic degradation of dimethyl phthalate by magnetic dual Z-scheme iron oxide/mpg-C3N4/BiOBr/polythiophene heterostructure photocatalyst under visible light

A new magnetic dual Z-scheme heterostructure photocatalyst, consisting of mesoporous graphitic carbon nitride (mpg-C3N4), BiOBr, polythiophene (PTh), and magnetic iron oxide, was developed, and its structural, optical, and electrochemical properties were analyzed. The photocatalyst was employed for the degradation of dimethyl phthalate (DMP) in water under visible light to evaluate its photocatalytic activity. The results revealed that the photocatalytic activity of the new heterostructure photocatalyst was superior to that of its single-component counterparts. The reaction kinetics of photocatalytic DMP degradation followed pseudo first-order kinetics and the reaction rate constant was 3.7- and 4.5-fold higher than those of pristine g-C3N4 and BiOBr, respectively. The enhanced photocatalytic performance was chiefly attributed to the dual Z-scheme heterostructure generated between mpg-C3N4, PTh, and BiOBr, which effectively hindered the recombination of photogenerated electron and hole pairs in mpg-C3N4 and BiOBr, improving the photogenerated carrier transfer efficiency. Radical trapping test results indicated that the active species, h+, ·O2–, and ·OH, coexisted during the photocatalytic reaction process, and that h+ played a major role in the destruction of DMP molecules. DMP was degraded into intermediate small-molecule products, such as acids and alcohols, which were ultimately mineralized to CO2 and H2O. The magnetic property of the new heterostructure photocatalyst enabled its straightforward separation from water using magnetic separation technology for further reuse. This study provides a new material and method for the effective removal of DMP from aqueous solution.

Phthalic Acid Esters: Natural Sources and Biological Activities.

Phthalic acid esters (PAEs) are a class of lipophilic chemicals widely used as plasticizers and additives to improve various products’ mechanical extensibility and flexibility. At present, synthesized PAEs, which are considered to cause potential hazards to ecosystem functioning and public health, have been easily detected in the atmosphere, water, soil, and sediments; PAEs are also frequently discovered in plant and microorganism sources, suggesting the possibility that they might be biosynthesized in nature. In this review, we summarize that PAEs have not only been identified in the organic solvent extracts, root exudates, and essential oils of a large number of different plant species, but also isolated and purified from various algae, bacteria, and fungi. Dominant PAEs identified from natural sources generally include di-n-butyl phthalate, diethyl phthalate, dimethyl phthalate, di(2-ethylhexyl) phthalate, diisobutyl phthalate, diisooctyl phthalate, etc. Further studies reveal that PAEs can be biosynthesized by at least several algae. PAEs are reported to possess allelopathic, antimicrobial, insecticidal, and other biological activities, which might enhance the competitiveness of plants, algae, and microorganisms to better accommodate biotic and abiotic stress. These findings suggest that PAEs should not be treated solely as a “human-made pollutant” simply because they have been extensively synthesized and utilized; on the other hand, synthesized PAEs entering the ecosystem might disrupt the metabolic process of certain plant, algal, and microbial communities. Therefore, further studies are required to elucidate the relevant mechanisms and ecological consequences.

Study of atmospheric pressure chemical ionization of phthalates in air by ion mobility spectrometry/mass spectrometry.

Phthalates are widely used in consumer products in the chemical industries. Due to their abundance in the milieu, their potentially harmful effect on the environment, human and animal health there is a need for sensitive and fast methods for their detection. Positive polarity Corona Discharge Atmospheric Pressure Chemical Ionization (CD-APCI) in the air was applied for ionization of phthalates. The ionization method for the phthalates was studied by atmospheric pressure Ion Mobility Spectrometry (IMS) and hybrid IMS/orthogonal acceleration Time-of-Flight Mass spectrometry (IMS-oaTOF-MS). CD-APCI IMS and MS spectra of selected phthalates (dimethyl phthalate, diethyl phthalate, diethyl isophthalate, diethyl terephthalate, dipropyl phthalate, diisopropyl phthalate, dibutyl phthalate, diisobutyl phthalate, and dibutyl terephthalate) were recorded. In the case of the ortho- and "iso"-isomers exclusively the protonated molecular ions [M+H]+ were detected. In the case of the para- and meta-isomers and regioisomers, APCI resulted in the appearance of hydrated protonated molecular ions [M + H]+ ·(H2 O)0,1,2 . The ion mobilities, collision cross-sections of these ions in air, as well as the limits of detection (LODs) for the phthalate vapors, were determined. In the case of isomeric phthalates, we have demonstrated the potential of the IMS technique for their separation. The results show that CD-APCI in combination with IMS and IMS-oaTOF-MS is a suitable method for the fast and sensitive detection of phthalates with the potential to separate some isomers.

Spin-column micro-solid phase extraction of phthalate esters using electrospun polyacrylonitrile/iron (III)/Mg-based metal-organic framework 88B followed by GC analysis

An electrospun composite polyacrylonitrile/iron (III)/Mg-based metal–organic framework 88B (PAN/Fe/Mg-MIL-88B) was prepared, and then utilized as a viable sorbent for the simultaneous determination of five phthalate esters in store-bought bottled mineral water and orange juice, urine, plasma, and two different types of cream and lipstick applying spin column micro solid-phase extraction (SC-μSPE) method. The synthesis of the electrospun nanofibers was surveyed using energy-dispersive X-ray spectroscopy, X-ray diffraction analysis and Fourier transform infrared spectroscopy, while the morphology of the composite was investigated using field emission scanning electron microscopy. The presence of Fe/Mg-MIL-88B with high quantity of functional groups and porous structure in the polymer matrix endows the PAN nanofibers with high extraction efficiency. The effect of MOF% in the composite nanofibers, amount of sorbent, sample pH, type and volume of desorption solvent, salt concentration, number of cycles, and centrifugation speed were optimized. Under the optimal conditions, the calibration plots for dimethyl phthalate (DMP), diethyl phthalate (DEP), and diallyl phthalate (DAP) were linear within the range of 1.0–1000.0 ng mL−1; and 0.5–1000.0 ng mL−1 for diisobutyl phthalate (DIBP) and dibutyl phthalate (DBP). The limits of detection were lower than 0.30 ng mL−1 for DMP, DEP, and DAP and 0.15 ng mL−1 for DIBP and DBP by GC-FID. The data related to the relative standard deviations were in the range of 4.1%–6.3% (intra-day, n = 5) and 6.4%–7.9% (inter-day, n = 3) in the span of three days. Finally, the applicability of the method was scrutinized for the quantification of analytes of interest in spiked samples, and satisfactory recoveries were attained within the range of 84.8–102.8%.

Optimizing the activation efficiency of sub-3 nm particles in a laminar flow condensation particle counter: Model simulation

The measurement of airborne particles with sizes below 3 nm is critical, as it helps the understanding of atmospheric nucleation and elucidates important particle synthesis mechanisms in the gas phase. Condensation particle counters (CPCs) have been widely used to measure the concentration of aerosols. However, it is challenging for the CPCs to measure particles below 3 nm due to the insufficient activation of these particles via vapor condensation. Methods have been proposed to increase the saturation ratio of the condensing vapor to promote the detection efficiency of sub-3 nm particles in the CPCs. Different working fluids also make a considerable impact on particle detection. Given the various types of parameters and the wide range of values these parameters can take, modeling studies are needed in searching for the optimal operating conditions of a CPC.In this work, we simulated the sub-3 nm particle activation and growth in a laminar flow CPC using COMSOL Multiphysics®, which has the advantages of simulating complex flow conditions and interfacing with post-processing software such as MATLAB. Our simulation incorporates the influence of temperature-dependent air and working fluid properties on particle activation and the impact of latent heat and non-continuum effects on droplet growth. Following the method introduced by Iida, Stolzenburg and McMurry (2009), particle activation is optimized for a given working fluid and condenser temperature by adjusting the saturator temperature to achieve a homogeneous nucleation rate of 1 s−1. The results, characterized by Dkel,0 (largest particle size that cannot be activated) and Dkel,50 (particle size activated with 50% efficiency), were compared against the analytical Graetz model used in Stolzenburg (1988). Our COMSOL simulations show that glycerine, diethylene glycol, ethylene glycol, 2-aminoethanol, and dimethyl phthalate are the best five working fluids achieving the smallest Dkel,50 among 45 commonly used solvents. The Dkel,50 values simulated by COMSOL under a condenser temperature of 10 °C for the five working fluids are 1.56, 1.88, 1.92, 1.98, and 2.10 nm, respectively, while the values simulated by the analytical Graetz solution differ slightly from 0.4% to 0.7%. The results demonstrate excellent agreement between these two simulation methods. For the five best working fluids activating the same 2.1 nm particles, the droplets can grow to sizes detectable by a second-stage CPC. The sensitivity of the COMSOL solution to the inlet condition and the form of convective diffusion equations is investigated. We also discussed the effect of CPC operating conditions, such as the condenser geometry and flow conditions, on particle activation for optimizing the performance of the CPC in detecting sub-3 nm particles.