Dialkyl Phthalates Research Articles

Effect of biochar aging on surface characteristics and adsorption behavior of dialkyl phthalates

The implications of biochar aging regarding their material properties as well as their interactions with other contaminants are not vivid. We report the role of biochar aging on sorption behavior of di-alkyl phthalates (PAEs). Biochars used in this study were produced from peanut-shell and their aging was simulated by chemical oxidation. The structural composition and morphology of the obtained biochars, before and after oxidation with HNO3/H2SO4, were analyzed by element composition, XPS, DRIFT, and SEM/EDX. Several experimental results unequivocally showed oxygen enrichment in the mixed acid treated samples compared to their precursors. Despite surface area reduction and pore destruction, increased PAEs sorption on oxidized biochar surfaces portrayed existence of strong PAEs binding sites. The adsorption of PAEs on oxidized biochar surface is a cumulative influence of hydrophobic interactions and pi–pi electron donor–acceptor interactions. Our results suggest that imminent aging of biochar upon environmental exposure may change their sorbent properties.

ChemInform Abstract: A Two‐Step, Stereoselective Synthesis of Nine‐ and Ten‐Membered Carbocycles from Phthalates.

A two-step, stereoselective procedure for the synthesis of nine- and ten-membered carbocycles from readily available phthalates is described. A variety of dialkyl phthalates have been transformed into [6,n]-fused bicyclo systems (n = 5, 6, 7) by a dearomatization/cyclization process and then converted into cyclonona- and cyclodecadienes through a bond cleavage reaction, whereby both processes are promoted by alkaline metals in THF.

Estimation of the presence of unmetabolized dialkyl phthalates in untreated human urine by an on-line miniaturized reliable method

At present, human exposure to dialkyl phthalates is assessed through urinary measurement of their metabolites due mainly to contamination in their analysis by their ubiquitous presence. An on-line miniaturized method and the processing of the untreated urine samples have been the key factors for minimizing contamination and achieving unbiased results. Di(2-ethylhexyl) (DEHP), diethyl (DEP), dibutyl (DBP) and mono-ethylhexyl (MEHP) phthalates in urine samples have been included in the study; MEHP as metabolite of the main dialkyl phthalate such as DEHP. On-line in-tube solid-phase microextraction (IT-SPME)-capillary liquid chromatography (CapLC) with diode array detection (DAD) is employed. The detection limits (LODs) achieved in urine were between 0.5 and 1.5μg/L. Eighteen urines were processed. DBP and DEHP were found in nine and five samples, respectively and DEP in three of them. MEHP was only detected in one of the eighteen samples analyzed.

A two-step, stereoselective synthesis of nine- and ten-membered carbocycles from phthalates.

A two-step, stereoselective procedure for the synthesis of nine- and ten-membered carbocycles from readily available phthalates is described. A variety of dialkyl phthalates have been transformed into [6,n]-fused bicyclo systems (n = 5, 6, 7) by a dearomatization/cyclization process and then converted into cyclonona- and cyclodecadienes through a bond cleavage reaction, whereby both processes are promoted by alkaline metals in THF.

Biodegradation of an endocrine-disrupting chemical di-n-butyl phthalate by newly isolated Camelimonas sp. and enzymatic properties of its hydrolase

An aerobic bacterial strain M11 capable of degrading dibutyl phthalate (DBP) was isolated and identified as Camelimonas sp. This strain could not grow on dialkyl phthalates, including dimethyl, diethyl, dipropyl, dibutyl and dipentyl phthalate, but suspensions of cells could transform these compounds to phthalate via corresponding monoalkyl phthalates. The degradation kinetics of DBP was best fitted by first-order kinetic equation. During growth in Brucella Selective Medium, M11 produced the high amounts of non-DBP-induced intracellular hydrolase in the stationary phase. The DBP hydrolase gene of M11 was cloned, and the recombinant DBP hydrolase had a high optimum degradation temperature (50°C), and a wide range of pH and temperature stability.

Physicochemical and biochemical properties for the dialkyl phthalates

Abraham descriptors for 40 phthalate esters have been calculated from a variety of experimental data, including water–solvent partition coefficients, high performance liquid chromatographic and gas chromatographic retention times. These descriptors can then be used to calculate a large number of physicochemical and biochemical properties of the esters; values are given for dinonyl phthalate as an example. Once the Abraham descriptors have been obtained for a given phthalate ester, no more than simple arithmetic is needed to calculate values of a huge range of properties. The ‘three solubility method’ yields data that are consistent for a particular physicochemical property, but not necessarily correct data. Previous literature values for air–water partition coefficients for the higher phthalates are likely to be incorrect by several orders of magnitude.

Extraction and subsequent determination of dialkyl phthalates in the soil using gas chromatography combined with tandem mass spectrometry

A method for the extraction and subsequent quantitative determination of dialkyl phthalates (DAPs) in soil using gas chromatography combined with tandem mass spectrometry is suggested. The method is characterized by low limits of detection, as well as high sensitivity and selectivity. The optimal conditions for DAP extraction from soils were selected and evaluation of the possible secondary contamination of DAP samples from labware and chemicals and distribution of DAP in soil were performed.

Mutual Effects of Dialkyl Phthalate Esters and Humic Acid Sorption on Carbon Nanotubes in Aqueous Environments

Various reaction sequences of mutual sorptions of dimethyl phthalate (DMP) or diethyl phthalate (DEP) and humic acid (HA) on single-walled carbon nanotubes (SWCNT) and multi-walled carbon nanotubes (MWCNT) were studied. The results indicate that the sorption of DMP and DEP on CNT decreases owing to its competition effect in the presence of HA. The competition is stronger at lower HA concentration. At higher HA concentration, weaker competition has occurred because there are steric hindrance and pore blockage of HA on CNT. The reaction sequences of DMP (or DEP) and HA sorption could affect their sorption mechanisms. The initial sorbed HA can modify the surface properties of CNT with a concomitant effect on the partial complexation of DMP (or DEP) with the sorbed HA. The Fourier transform infrared (FTIR) spectra indicate that SWCNT and MWCNT contain mainly −COO– and −COOH moieties, respectively. In addition, the IR spectroscopic and thermogravimetric analyses illustrate that CNTs provide similar sorption ca...

Equilibrium Binding Interactions Between Lotrafilcon A Soft Contact Lenses and the Two Prostaglandin Antiglaucoma Drugs Bimatoprost and Tafluprost

To determine the equilibrium binding constant (EB) values of bimatoprost and tafluprost drug product formulations in contact with lotrafilcon A soft contact lenses and to characterize the importance of drug molecule hydrophobicity in controlling the binding interactions. Bimatoprost Ophthalmic Solution and Tafluprost Ophthalmic Solution (Saflutan) were incubated with lotrafilcon A lens material for timed intervals at 25°C and 37°C. Aliquots were withdrawn, filtered, and tested using reverse-phase ultrahigh-performance liquid chromatography with respect to [bimatoprost] or [tafluprost] remaining in the solution. A series of homologous dialkyl phthalate esters and a series of homologous p-hydroxybenzoic acid alkyl esters were also tested as reference compounds. Bimatoprost and tafluprost were rapidly (within 15 min) absorbed from the solution by lotrafilcon A lenses, reaching an equilibrium within 60 min. At any lens:solution (w/v) ratio, the extent of drug binding to lens material was greater for tafluprost than for bimatoprost. The log(EB) values correlated with solute octanol:water partition coefficient (logP) values, indicating that hydrophobic interactions are important in controlling solute partitioning into the lens material. This study established the quantitative relationships between tafluprost and bimatoprost binding to lotrafilcon A lenses. The fraction of bimatoprost or tafluprost that binds to lotrafilcon A increases with increasing lens:solution (w/v) ratio. For a 60 µL dose volume applied to a single contact lens, 16% of initially present bimatoprost remains in the solution, whereas only 6% of initially present tafluprost remains in the solution. These calculations clearly demonstrate that both drugs partition extensively into lotrafilcon A contact lens material. Although the clinical implications of such binding can only be surmised, it would seem prudent to caution contact lens wearers to remove the lenses before administering either prostaglandin drug.

Prenatal developmental toxicity studies on diundecyl and ditridecyl phthalates in Sprague-Dawley rats

This study evaluates the developmental toxicity of two high molecular weight dialkyl phthalate esters, diundecyl phthalate (DUDP) and ditridecyl phthalate (DTDP). Sprague-Dawley rats were administered 0, 0.25, 0.50, or 1g/kg/day of DUDP or DTDP, by gavage, on gestation days 6–20. DUDP and DTDP had no adverse effects on maternal body weight and food consumption. The number of live fetuses, percent of post-implantation loss and of resorptions, fetal sex, and fetal body weights were not affected by either phthalate. There was no evidence of teratogenicity, whatever treatment. Small decreases in the anogenital distance of male fetuses were noted at 0.5 and 1g DUDP/kg/day. The incidence of fetuses with supernumerary lumbar ribs was significantly higher than control at 0.5 and 1g DUDP/kg/day. Thus, DTDP was not developmentally toxic up to 1g/kg/day and there were signs of DUDP-induced fetal effects at 0.5 and 1g/kg/day.

Remarkable Activation of an Alkyne [2+2+2]-Cycloaddition Catalyst, 2-Iminomethylpyridine (dipimp)/CoCl2·6H2O/Zn, by a Phthalate Additive

A catalyst for alkyne [2+2+2]-cycloaddition reactions, 2-(2,6-diisopropylphenyl)iminomethylpyridine (dipimp)/CoCl2·6H2O/Zn, can be effectively activated by addition of a catalytic amount of dialkyl phthalate to enable reactions that cannot proceed under un­activated conditions. The activation by adding phthalate was ligand- and solvent-dependent, and it was unique to dipimp and N-methyl-2-pyrrolidone (NMP). With use of diphosphine ligand instead of dipimp or with use of tetrahydrofuran (THF) instead of NMP, no activation by a phthalate additive was observed. This simple method of catalyst activation with use of inexpensive, commercially available compounds is highly practical and may find many applications.

An interlaboratory comparison study for the determination of dialkyl phthalate esters in environmental and biological samples

A series of interlaboratory comparison exercises were conducted to assess the accuracy of dialkyl phthalate ester (DPE) concentration measurements in environmental and biological samples. Five laboratories participated in analyses to determine DPE concentrations in standard test solutions; marine sediments; three certified reference materials, including CARP-2 (fish muscle) and BCR-07 (fortified milk powder); and several livestock samples (sheep's milk, liver, and muscle). In addition, one laboratory determined DPE residue concentrations in 20 municipal sewage sludge samples, previously analyzed as part of the 2006/2007 U.S. Environmental Protection Agency's Targeted National Sewage Sludge Survey (TNSSS). The results showed relatively good interlaboratory agreement for analyses of di-ethylhexyl phthalate (DEHP). Three independent laboratories (Labs A, B, and C) reported concentrations of DEHP (ng/g wet wt) in fish muscle (CARP-2) of 1,550 ± 148, 1,410 ± 193, and 1,380 ± 187, respectively. Similarly, DEHP concentration measurements in sewage sludge samples showed good agreement with those reported in the 2006/2007 TNSSS report. Measured concentrations of individual DPEs and C6-C10 isomeric mixtures in these samples of municipal sewage sludge, which have not been previously reported, ranged between 1 and 200,000 ng/g dry weight. The results demonstrate that environmental monitoring of DPEs is often hampered by high method detection limits (MDLs), due to contamination of procedural blanks. It is important to note, however, that when background contamination is minimized (<10 ng/sample), relatively low MDLs (<0.1 ng/g) can be achieved, allowing for low-level quantification of DPEs in environmental and biological samples. Future efforts to develop better protocols to lower MDLs, as well to develop reference materials, would greatly benefit future DPE monitoring initiatives.

Cloning of a dibutyl phthalate hydrolase gene from Acinetobacter sp. strain M673 and functional analysis of its expression product in Escherichia coli

A dibutyl phthalate (DBP) transforming bacterium, strain M673, was isolated and identified as Acinetobacter sp. This strain could not grow on dialkyl phthalates, including dimethyl, diethyl, dipropyl, dibutyl, dipentyl, dihexyl, di(2-ethylhexyl), di-n-octyl, and dinonyl phthalate, but suspensions of cells could transform these compounds to phthalate via corresponding monoalkyl phthalates. During growth in Luria-Bertani medium, M673 produced the high amounts of non-DBP-induced intracellular hydrolase in the stationary phase. One DBP hydrolase gene containing an open reading frame of 1,095 bp was screened from a genomic library, and its expression product hydrolyzed various dialkyl phthalates to the corresponding monoalkyl phthalates.

Efficient synthesis of symmetrical phthalate and maleate diesters using phosphinite ionic liquids

Symmetrical dialkyl phthalates and maleates were synthesized using phosphinite ionic liquid as a catalyst and reaction medium. The results indicated that phosphinite ionic liquid shows better catalytic and reusable performance without using any acid or base catalyst. Under the optimum conditions, using 1-methyl-3-(4-phosphinitebutyl) imidazolium chloride as catalyst, the conversion of phthalic and maleic anhydrides to the corresponding diesters of primary and secondary alcohols was occurred in 72–85% yields. The diesters of tertiary alcohols and phenols could not be prepared by this method. A kind of widely used plasticizer, dioctyl phthalate, was prepared in good yield under these conditions. The ionic liquid could be reused three times after easy separation from the products without any disposal.

Prenatal developmental toxicity studies on di- n-heptyl and di- n-octyl phthalates in Sprague-Dawley rats

This study evaluates the developmental toxicity of two dialkyl phthalate esters, di- n-heptyl phthalate (DHPP) and di- n-octyl (DnOP) phthalate, which have straight-alkyl side chains of seven and eight carbons, respectively. Sprague-Dawley rats were administered 0, 0.25, 0.50, or 1 g/kg/day of DHPP or DnOP, by gavage, on gestation days 6–20. DHPP and DnOP had no adverse effect on maternal feed consumption and body weight gain, or on the incidence of post-implantation loss and fetal body weight. There was no increase in the incidence of fetal malformations or external and visceral variations, whatever treatment. A significant increase in rudimentary lumbar ribs was observed at all doses of DHPP and DnOP. The anogenital distance of the male fetuses was significantly decreased at the highest dose of DHPP. This parameter was not affected by DnOP. Thus, the lowest-observed-adverse-effect level (LOAEL) for developmental toxicity was 0.25 g/kg/day for DHPP and DnOP.

Chromatographic characteristics of poly(1-vinylimidazole)-grafted silica in normal-phase HPLC

A stationary phase based on poly(1-vinylimidazole)-grafted silica has been prepared by the surface radical chain-transfer reaction. The stationary phase was characterized by infrared spectra, X-ray photoelectron spectroscopy and elemental analysis. Chromatographic characteristics of the stationary phase were investigated in normal-phase HPLC. The results showed that both weak polar compounds (polycyclic aromatic hydrocarbons, dialkyl phthalates) and polar compounds (anilines, phenols) could be successfully separated on this stationary phase, implying better separation performance than blank silica and conventional aminopropyl-bonded silica under the same conditions. The excellent performance can be attributed to multiple interactions between surface modifier and the analytes that might include dipole, hydrogen bonding, H-π, electrostatic and inductive interactions.

Plasticization of cellulose ethers used in the film coating of tablets.

Plasticizer/polymer interactions have been studied by measuring the intrinsic viscosities of both ethyl cellulose and hydroxypropyl methylcellulose in a series of dialkyl phthalates and in a series of liquid glycols respectively. A correlation was found between the intrinsic viscosity of the polymer/plasticizer solutions and the tensile strength, elongation at rupture and work done in stressing to failure of cast films--the mechanical properties being at a minimum when the intrinsic viscosity was at a maximum. This correlation held only within a homologous series of plasticizers and none was found for plasticizers of different structures. A relationship was found between the lowering of a calculated glass transition temperature of hydroxypropyl methylcellulose in the presence of the plasticizers propylene glycol, polyethylene glycol 200 and glycerol and the intrinsic viscosity of the corresponding solutions--the higher the viscosity the greater the lowering of the transition temperature.

Patent Literature on Mosquito Repellent Inventions which Contain Plant Essential Oils - A Review

Bites Bites of mosquitoes belonging to the genera Anopheles Meigen, Aedes Meigen, Culex L. and Haemagogus L. are a general nuisance and are responsible for the transmission of important tropical diseases such as malaria, hemorrhagic dengue and yellow fevers and filariasis (elephantiasis). Plants are traditional sources of mosquito repelling essential oils (EOs), glyceridic oils and repellent and synergistic chemicals. A Chemical Abstracts search on mosquito repellent inventions containing plant-derived EOs revealed 144 active patents mostly from Asia. Chinese, Japanese and Korean language patents and those of India (in English) accounted for roughly 3/4 of all patents. Since 1998 patents on EO-containing mosquito repellent inventions have almost doubled about every 4 years. In general, these patents describe repellent compositions for use in topical agents, cosmetic products, incense, fumigants, indoor and outdoor sprays, fibers, textiles among other applications. 67 EOs and 9 glyceridic oils were individually cited in at least 2 patents. Over 1/2 of all patents named just one EO. Citronella [Cymbopogon nardus (L.) Rendle, C.winterianus Jowitt ex Bor] and eucalyptus (Eucalyptus LʼHér. spp.) EOs were each cited in approximately 1/3 of all patents. Camphor [Cinnamomum camphora (L.) J. Presl], cinnamon (Cinnamomum zeylanicum Blume), clove [Syzygium aromaticum (L.) Merr. & L.M. Perry], geranium (Pelargonium graveolens LʼHér.), lavender (Lavandula angustifolia Mill.), lemon [Citrus × limon (L.) Osbeck], lemongrass [Cymbopogon citratus (DC.) Stapf] and peppermint (Mentha × piperita L.) EOs were each cited in > 10% of patents. Repellent chemicals present in EO compositions or added as pure “natural” ingredients such as geraniol, limonene, p-menthane-3,8-diol, nepetalactone and vanillin were described in approximately 40% of all patents. About 25% of EO-containing inventions included or were made to be used with synthetic insect control agents having mosquito repellent properties such as pyrethroids, N,N-diethyl-m-toluamide (DEET), (±)-p-menthane-3,8-diol (PMD) and dialkyl phthalates. Synergistic effects involving one or more EOs and synthetic and/or natural components were claimed in about 10% of all patents. Scientific literature sources provide evidence for the mosquito repellency of many of the EOs and individual chemical components found in EOs used in patented repellent inventions.

Continuous full filling capillary electrochromatography-electrospraying chromatographic nanoparticles

The influence of instrumental parameters affecting the ionization in continuous full filling capillary electrochromatography/electrospray ionization mass spectrometry (CFF-CEC/ESI-MS) was investigated. The investigated parameters were the BGE and sheath liquid ion strength and organic modifier content, the nebulizer gas pressure, and the concentration of nanoparticles in the BGE. It was found that the nebulizer pressure had the largest influence on the separation efficiency and apparent retention. It was shown that even the lowest pressure investigated was sufficient to guide the nanoparticle flow away from the mass spectrometer inlet. A nebulizer pressure of 5 psi was found to be optimal; increasing the pressure significantly decreased the separation efficiency due to the generation of a hydrodynamic flow. Generally, the ion strength of both the BGE and the sheath liquid were found to have very moderate effects on the separation of a homologous series of dialkyl phthalates, whereas the ionization efficiency was found to be unaffected by the nanoparticles and the separation efficiency was found to increase with increasing concentrations up to 3.8 mg/mL, whereafter it was observed to drop. The optimized method was linear over a wide concentration range and presented LOD and LOQ more than threefold lower than those previously reported using CFF-CEC/ESI-MS.

Adsorption of Dialkyl Phthalate Esters on Carbon Nanotubes

Dialkyl phthalate esters (DPEs), with endocrine disrupting functions, are widely used and categorized as priority pollutants. Carbon nanotubes (CNTs) as strong adsorbents could influence the fate, transport, and bioavailability of DPEs in the environment. Understanding adsorptive interactions between CNTs and DPEs is critical to the environmental applications of CNTs. Adsorption of DPEs by one type of single-walled CNTs (SWCNT) and three multiwalled CNTs (MWCNT) was evaluated. For a given CNT, the adsorptive affinity correlated well with hydrophobicity of DPEs with an order of dimethyl phthalate (DMP) < diethyl phthalate (DEP) < dibutyl phthalate (DBP). The normalized adsorption coefficient (K/K(HW)) of DPEs indicates that π-π electron-donor-acceptor (EDA) interaction was also important for adsorption of DPEs (π-acceptor) on CNTs (π-donor). A π-π charge-transfer band of EDA complexes (mixture of pyrene (PYR) as π-donor and DPEs as π-acceptor) showed their interaction strength in the order of DMP-PYR > DEP-PYR > DBP-PYR. Calculated monolayer adsorption capacities (log Q) were bigger (for DMP and DEP) than or approximately equal to (for DBP) the estimated adsorption capacities (log Q(0)), implying that the DPEs were adsorbed on the surface area of CNTs. For a given DPE, the adsorptive capacities decreased with the increasing outer diameters of CNTs in the order of SWCNT > MWCNT10 > MWCNT20 > MWCNT40.