Presence Of Dibutyl Phthalate Research Articles

Ultrasensitive, Label-Free Voltammetric Detection of Dibutyl Phthalate Based on Poly-l-lysine/poly(3,4-ethylenedioxythiophene)-porous Graphene Nanocomposite and Molecularly Imprinted Polymers.

Development of an efficient technique for accurate and sensitive dibutyl phthalate (DBP) determination is crucial for food safety and environment protection. An ultrasensitive molecularly imprinted polymers (MIP) voltammetric sensor was herein engineered for the specific determination of DBP using poly-l-lysine/poly(3,4-ethylenedioxythiophene)/porous graphene nanocomposite (PLL/PEDOT-PG) and poly(o-phenylenediamine)-imprinted film as a label-free and sensing platform. Fabrication of PEDOT-PG nanocomposites was achieved through a simple liquid-liquid interfacial polymerization. Subsequently, poly-l-lysine (PLL) functionalization was employed to enhance the dispersibility and stability of the prepared PEDOT-PG, as well as promote its adhesion on the sensor surface. In the presence of DBP, the imprinted poly(o-phenylenediamine) film was formed on the surface of PLL/PEDOT-PG. Investigation of the physical properties and electrochemical behavior of the MIP/PLL/PEDOT-PG indicates that the incorporation of PG into PEDOT, with PLL uniformly wrapping its surface, significantly enhanced conductivity, carrier mobility, stability, and provided a larger surface area for specific recognition sites. Under optimal experimental conditions, the electrochemical response exhibited a linear relationship with a logarithm of DBP concentration within the range of 1 fM to 5 µM, with the detection limit as low as 0.88 fM. The method demonstrated exceptional stability and repeatability and has been successfully applied to quantify DBP in plastic packaging materials.

Multispectral method combined with molecular modelling to investigate the binding mechanisms of DBP and DIBP on pepsin

The binding mechanisms of dibutyl phthalate (DBP) and diisobutyl phthalate (DIBP) with pepsin (PEP) were investigated by multispectral method and computational techniques (molecular docking, molecular dynamics, surface electrostatic potential), as well as cytotoxicity assay. Fluorescence studies revealed that both DBP and DIBP had a static bursting effect on PEP, forming a stable complex. Furthermore, the formation of PEP-DBP/DIBP complexes was observed to occur spontaneously (ΔG < 0), driven by the interactions of hydrogen bonding and van der Waals forces. PEP exhibits a higher binding constant Ka of DBP (3.30 × 104 L·mol−1) compared to that of DIBP (2.37 × 104 L·mol−1). The higher stability of PEP-DBP complexes can be attributed to the different branching structures of DBP and DIBP, this observation was further supported by the larger negative surface area of DBP (125.90 Å2) in the ESP analysis, and were aligned with the MD simulations results of more stable RMSD and lower Rg value in presence of DBP. Computational analysis revealed that both DBP and DIBP exhibited binding interactions with the fluorescent groups (Tyr 75, Phe 111, and Phe 117) by van der Waals forces. DBP/DIBP binds to the Asp 32 and Asp 215 motifs of the catalytic activity center of PEP. Combined with the lower Rg values, CD tests suggested that the addition of DBP/DIBP caused the rise of α-Helix content thereby compacted the conformation structure of PEP into a compact shape. In addition, DBP generated more hydrogen bonds with PEP compared to DIBP, also as evidence to the higher stability of EPE-DBP. Finally, the IC50 of DBP and DIBP on Caco-2 cells were determined to be 5.16 × 10-4 mol·L-1 and 1.37 × 10-3 mol·L-1, respectively confirming the higher level of toxicity of DBP. The present study elucidates the effect and binding mechanism of DBP/DIBP on PEP at the molecular level, providing fundamental data for the impact and potential risk assessment of PAEs on the human digestive system.

Impacts of dibutyl phthalate on bacterial community composition and carbon and nitrogen metabolic pathways in a municipal wastewater treatment system

Dibutyl phthalate (DBP) is a typical toxic and hazardous pollutant in pharmaceutical wastewater, affecting the metabolism of microbial flora, leading to decreased treatment efficiency, and deteriorated effluent quality in municipal wastewater treatment plants (WWTPs). This study conducted a long-term experiment with 6 operational stages in a pilot-scale A2O-MBR system, analyzing the effect of DBP on the bacterial community and their carbon and nitrogen metabolic pathways. 16S rRNA gene amplicon sequencing analysis and principal components analysis (PCA) showed that DBP at 8 mg/L significantly influenced the structure of bacterial community (P < 0.05), resulting in reduced bacterial community diversity. Metagenomic analysis was used to explore the embedded carbon and nitrogen metabolic pathways. At the presence of DBP, the metabolism of saccharides, lipids, and aromatic compounds were blocked owing to the vanishment of key enzyme (such as acetylaminohexosyltransferase (EC 2.4.1.92) and UDP-sugar pyro phosphorylase (EC 2.7.7.64)) encoding genes, resulting in weakened carbon metabolism, and thus reduced COD removal performance. The resultant deficiency of the genes such as those encoding hydroxyproline dehydrogenase (EC 1.5.5.3) gave rise to interrupted metabolic pathways of amino acid (arginine, proline, tyrosine, and tryptophan), resulting in declined function of nitrogen metabolism and thus reduced TN removal efficiency. The uncovery of the mechanisms by which DBP affects wastewater treatment system efficiency and microbial metabolism is of theoretical importance for the efficient operation of municipal and pharmaceutical wastewater treatment systems.

Changes in the Concentration of Phthalic Acid Esters in the Plastic Materials of Vehicles During the Usage

The presence of dibutyl phthalate (DBP) and di-2-ethylhexyl phthalate (DEHP) was monitored in 16 automotive plastic samples (steering wheel, dashboard, seats, headrests, and air conditioning control). The plastic samples were obtained from a crashed vehicle that had been in operation for only one month. Phthalates were determined by HPLC. The first analysis was performed immediately after the sample preparation, the second one after 3 months of storage, the third one after 6 months of storage, the fourth one after 9 months of storage, and the fifth one after 15 months of storage. The average DBP concentrations ranged from 1.3 to 197.1 μg g–1 of plastic at the beginning, 1.7to 161.5 μg g–1 of plastic in the 3rd month, 0.5 to 78.9 μg g–1 of plastic in the 6th month, 2.3 to 123.3 μg g–1 of plastic in the 9th month, and 14.0 to 98.6 μg g–1 of plastic in the 15th month. The average DEHP concentrations ranged from 1,7 to 185,7 μg g–1 of plastic at the beginning, 3,9 to 45,4 μg g–1 of plastic in the 3rd month, 1,4 to 252,4 μg g–1 of plastic on the 6th month, 5,1 to 41,7 μg g–1 in the 9th month, and 2,3 to 87,5 μg g–1 in the 15th month. In particular, higher concentrations were found in soft plastics. An interesting finding is that the content of both phthalates (DBP and DEHP) was also present in leather materials. According to the comparison of phthalates concentrations during storage, it can be stated that phthalates concentration decreases with time and, after approximately 15 months of storage, concentrations decreased: for DBP by 20 to 90% (in 44% samples) and for DEHP by 30 to 90% (in 70% samples). For the other samples, the increase of both phthalates was probably due to depolymerisation of the plastics by UV exposure, temperature and storage time. Phthalates are human carcinogens and they can cause the death or tissue malformation. They are dangerous for liver function. The legislation of the Czech Republic and European Union has not yet dealt with these problems.

Acute and chronic combined effect of polystyrene microplastics and dibutyl phthalate on the marine copepod Tigriopus japonicus

Dibutyl phthalate (DBP) is a commonly used additive in plastic products, so it may potentially coexist with microplastics (MPs) in marine environment. The ingestion of MPs might affect the accumulation of DBP in marine organisms. In this study, the marine copepod Tigriopus japonicus was applied to study the combined effect of DBP and polystyrene microplastics (mPS) on the copepod through both acute mortality tests and chronic reproduction tests. The LC50 of DBP was 1.23 mg L−1 (95% CI: 1.11–1.35 mg L−1), while exposure to mPS didn’t have significant lethal effect on the copepods. Adsorption to MPs led to decreased bioavailability of DBP, resulting in decreased toxicity of DBP. In contrast to the results of acute toxicity tests, DBP didn’t affect the reproduction of the copepods at lower exposure concentrations, while mPS reduced the number of nauplii and extended the time to hatch. Similar as acute toxicity tests, antagonistic interaction was observed for mPS and DBP in chronic reproduction tests, which might be attributed to promoted aggregation of mPS at presence of DBP. Overall, antagonistic toxicity effect between the two pollutants was observed for both acute and chronic tests, but the mechanisms of the interaction between DBP and mPS were different. Results of the present study highlighted the importance of long-term exposure when evaluating the toxic effect of MPs and their combined effect with other chemicals.

Ecotoxicological and biochemical effects of environmental concentrations of the plastic-bond pollutant dibutyl phthalate on Scenedesmus sp.

Phthalate esters are highly present in aquatic plastic litter, which can interfere with the biological processes in the wildlife. In this work, the commonly found freshwater microalga Scenedesmus sp. was exposed to environmental concentrations (0.02, 1 and 100 μg L−1) and to a higher concentration (500 μg L−1) of dibutyl phthalate (DBP), which is an environmental pollutant. The growth, pH variation, production of photosynthetic pigments, proteins and carbohydrates were evaluated. The main inhibition effect of DBP on the microalgal growth was observed in the first 48 h of the exposure (EC50: 41.88 μg L-1). A reduction in the photosynthetic pigment concentration was observed for the 0.02, 1 and 100 μg L-1 conditions indicating that the DBP downregulated the growth rate and affected the photosynthetic process. A significant increase in protein production was only observed under 500 μg L−1 DBP exposure. The extracellular carbohydrates production slightly decreased with the presence of DBP, with a stronger decrease occurring in the 500 μg L-1 condition. These results highlight the environmental risk evaluation and ecotoxicological effects of DBP on the production of biovaluable compounds by microalgae. The results also emphasize the importance of assessing the consequences of the environmental concentrations exposure as a result of the DBP dose-dependent correlation effects.

Chemical Constituents of Donkey Dung (Anbarnasara): Questioning the Recent Claims Concerning Therapeutic Effects

Background: Various animal excrements have been used as a medicine for the treatment of different diseases in the past. Today, people still use some of these excrements, especially female donkey dung (Anbarnasara,) by smelling the smoke of burnt dung for some ailments like sinusitis and bronchitis. Recently, some studies have focused on the therapeutic activities of Anbarnasara but no one has studied the active ingredients of it. Objective: The aim of this study was to identify the chemical constituents and antibacterial activities of Anbarnasara and its smoke. Materials and Methods: Female donkey dungs were collected from Shahreza in May 2017. The substance was burnt and the smoke was led to a beaker of methanol by a distillation apparatus. Then, the methanolic extract was dried via a rotary evaporator. Antibacterial activity of the smoke and also the total methanolic extract of Anbarnasara were tested on Staphylococcus aureus and Escherichia coli via well diffusion method. Chemical constituents were analyzed through gas chromatography-mass spectrometry (GC–MS) . Results: The results showed that Anbarnasara and its smoke have a very weak antibacterial activity. Regarding chemical constituents, both total methanolic extract and smoke extract predominantly contained toluene, xylene, and dibutyl phthalate. Conclusion: Previous studies showed xylene as one of the major components of the smoke of Anbarnasara. These articles also reported the presence of some plant-based compounds such as glyoxal, syringol, and limonene in the smoke. The presence of these compounds is probably due to the donkeys’ diet. In our study, the presence of dibutyl phthalate, an industrial plasticizer, among the components is probably due to environmental factors. These evidences suggested that Anbarnasara is under the influence of environmental factors like vegetation and pollutions and therefore, should be used as a medicine with caution. Recent claims regarding the antibacterial, cytotoxic, and wound healing activities of Anbarnasara should be considered independent of these environmental factors.

One-step preparation of graphene nanosheets via deflagration of obsoleted energetic materials

Herein, we report the large-scale preparation of graphene nanosheets via the deflagration of an obsoleted single base propellant in the presence of dibutyl phthalate (DBP) aiming at decreasing the oxygen balance. The high ambient pressure and high temperature generated during the deflagration process provided sufficient conditions for the efficient formation of carbon atoms and the subsequent shaping of graphene nanosheets. The prepared graphene nanosheets were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, and X-ray diffraction (XRD). This simple method is promising for future large-scale and cost-effective production of graphene nanosheets, as well as for the disposal of obsoleted energetic materials.

Lack of transient receptor potential melastatin 8 activation by phthalate esters that enhance contact hypersensitivity in mice

We studied the involvement of sensory neurons in skin sensitization to allergens using a mouse model in which the T-helper type 2 response is essential. Skin sensitization to fluorescein isothiocyanate (FITC) has been shown to be enhanced by several phthalate esters, including dibutyl phthalate (DBP). For different types of phthalate esters, we found a correlation between the ability of transient receptor potential (TRP) A1 activation and that of enhancing skin sensitization. A TRPA1-specific antagonist, HC-030031, was shown to suppress skin sensitization in the presence of DBP. However, since phthalate esters also activate TRPV1, phthalate esters could activate other types of TRP channels non-selectively. Furthermore, sensitization to FITC is also enhanced by menthol, which activates TRPA1 and TRPM8. Here we established an in vitro system for measuring TRPM8 activation. The selectivity for TRPM8 was established by the fact that two TRPM8 agonists (menthol and icilin) induced calcium mobilization, whereas agonists of TRPA1 and TRPV1 did not. We demonstrated that phthalate esters do not activate TRPM8. TRPA1-antagonist HC-030031 did not inhibit TRPM8 activation induced by menthol or icilin. These results show that phthalate esters activate TRPA1 and TRPV1 with selectivity. TRPM8 activation is not likely to be involved in the sensitization to FITC.

Thyroid hormone disrupting activities associated with phthalate esters in water sources from Yangtze River Delta

Thyroid hormone disrupting compounds in water sources is a concern. Thyroid hormone (TH) agonist and antagonist activities of water sources from the Yangtze River, Huaihe River, Taihu Lake and ground water in the Yangtze River Delta region were evaluated by use of a TH reporter gene assay based on the green monkey kidney fibroblast (CV-1). While weak TH receptor (TR) agonist potency was observed in only one of 15 water sources, antagonist potency was present in most of the water sources. TR antagonist equivalents could be explained by the presence of dibutyl phthalate (DBP), with concentrations ranging from 2.8×101 to 1.6×103μg DBP /L (ATR-EQ50s). None of the ground waters exhibited TH agonist potencies while all of the samples from Taihu Lake displayed notable TR antagonist potencies. To identify the responsible thyroid active compounds, instrumental analysis was conducted to measure a list of potential thyroid-disrupting chemicals, including organochlorine (OC) pesticides and phthalate esters. Combining the results of the instrumental analysis with those of the bioassay, DBP was determined to account for 17% to 144% of ATR-EQ50s in water sources. Furthermore, ATR-EQ20–80 ranges for TR antagonist activities indicated that samples from locations WX-1 and WX-2 posed the greatest health concern and the associated uncertainty may warrant further investigation.

Effects of phthalate esters on the sensitization phase of contact hypersensitivity induced by fluorescein isothiocyanate

Many different types of phthalate ester are used as plasticizers and are thus found in the air. There have been several studies that suggest an association between allergies and phthalate esters. We previously found that di-butyl phthalate (DBP) has an adjuvant effect in a mouse contact hypersensitivity model, in which fluorescein isothiocyanate (FITC) is involved as an immunogenic hapten. We examined whether other phthalate esters enhance the process of sensitization to FITC by facilitating the trafficking of FITC-presenting dendritic cells or macrophages from skin sites to draining lymph nodes. Mice were epicutaneously sensitized with FITC dissolved in acetone containing a phthalate ester. Sensitization was evaluated as ear swelling after a challenge with FITC. Draining lymph node cells obtained 24 h after skin sensitization were examined for FITC fluorescence by means of flow cytometry. FITC-positive cells were characterized with anti-CD11c and anti-CD11b by three-colour flow cytometry. When mice were sensitized with FITC in acetone containing DBP or di-n-propyl phthalate (DPP), strong enhancement of the ear-swelling response was observed. Di-methyl phthalate (DMP) and di-ethyl phthalate (DEP) were less effective but produced some enhancement. Consistent enhancement was not observed with di-(2-ethylhexyl) phthalate or di-isononyl phthalate. Upon sensitization in the presence of DBP or DPP, the number of FITC-positive dendritic cells (total CD11c+ as well as CD11c+/CD11b+) was increased in draining lymph nodes. As to the other four phthalate esters, there was no significant increase in the FITC-positive cell number in the draining lymph nodes. During the process of sensitization to FITC, DBP, and DPP exert strong adjuvant effects that are associated with enhancement of trafficking of antigen-presenting dendritic cells from the skin to draining lymph nodes.

Studies of a Supported Titanium Catalyst System Using Magnesium Dichloride–Alcohol Adduct

Magnesium dichloride reacts with aliphatic alcohols [ROH; R = n-C2H5, n-C3H7, i-C3H7, n-C4H9, i-C4H9, t-C4H9, n-C5H11, n-C6H13, C6H12(C2H5)] to form well-defined solid adducts. Compositional analysis of adducts indicates that the stoichiometric ratio of magnesium dichloride to alcohol depends on length of alkyl group and nature of isomeric alcohol. Magnesium dichloride-2-ethyl-l-hexanol adduct was treated with diphenyldichlorosilane in the presence of dibutylphthalate to obtain active magnesium dichloride support. The titanation process of active magnesium dichloride gives supported magnesium–titanium catalyst (Mg–Ti). The catalyst was characterized by compositional analysis and specific surface area measurements. Performance of the catalyst for polymerization of propene was evaluated with triethylaluminum (TEAL) and phenyltriethoxysilane (PES) as cocatalyst. The yield and isotacticity of the polymer is governed by polymerization parameters such as Si/A1 ratio and polymerization time.

The effect of dibutyl phthalate (DBP) plasticizer on the stability of optical properties of polystyrene (PS) after exposure to gamma radiation

The objective of this work was to study the effect of gamma radiation on the UV-visible transmission properties of PS/DBP solutions in the range containing 0–25wt% of DBP. Samples were prepared by bulk-polymerizing styrene in the presence of DBP. Transmission spectra before and at intervals after irradiation were characterized with a Hewlett-Packard 8452A diode array spectrophotometer. Glass transition temperatures were determined by a Du Pont 2910 DSC. Radiation-induced losses in transparency decreased as the glass transition temperatures decreased. Glass transition temperatures were unchanged by irradiation. GPC studies were conducted in filtered samples using a Polymer Laboratories PL gel 10-μm mixed-bed column. Molecular-weight distributions were broad, but decreased after irradiation. Number-average molecular weights increased after irradiation. Radiation damage is discussed in terms of the effect of matrix mobility on recoverable losses in transparency.

The occurrence of dibutyl phthalate in American cockroaches.

Abstract The presence of dibutyl phthalate in the American cockroach, Periplaneta americana (L.), was determined by means of gas chromatography-mass spectrometry. Each roach contained approximately 1.75 ppm of this compound. Since no source could be found in the rearing laboratories and since steps were taken to prevent contamination during laboratory processing, dibutyl phthalate apparently occurs naturally in the American cockroach.

The mechanism and kinetics of the heterogeneous polymerization of vinyl monomers I. The benzoyl peroxide catalyzed polymerization of vinyl chloride

A study has been made of the polymerization of vinyl chloride, with varying amounts of benzoyl peroxide at temperatures from 33 to 75° C. With from 0.025 to 1.0 mol. % benzoyl peroxide and over the above-mentioned temperature range, the rate of polymerization gradually accelerates over the first 30-40 % reaction. In the presence of a solvent for the polymer, such as dibutyl phthalate or tetrahydrofuran, however, the polymerization proceeds at a constant rate which decreases at later stages in the reaction. ‘Dead’ polyvinylchloride has been shown to act as a co-catalyst with benzoyl peroxide in the polymerization of vinyl chloride; in the absence of benzoyl peroxide, it does not catalyze the polymerization. Polyvinylchloride therefore exerts its catalytic effect when (a) the polymer is present in an undissolved state, and (b) benzoyl peroxide or another source of free radicals is also present in the reacting system. It is suggested that the co-catalytic effect of the ‘dead’ polymer is caused by an increase in the number of centres of polymer growth in the reacting system arising from chain transfer reactions between growing polymer chains and molecules of 'dead’ polymer resulting in the accumulation of stabilized centres of polymer growth on the surface of the solid polymer; the revivified polymer grows by addition of monomer until it is finally terminated by chain transfer with monomer, with the production of a mobile free radical. Relative values of the average molecular weight of polymer formed (a) at different temperatures, (b) at different stages in the reaction, (c) with different concentrations of benzoyl peroxide, and (d) in the presence of dibutyl phthalate, have been obtained. The results support the suggestion that chain transfer takes place to a considerable extent in the polymerization of vinyl chloride.