Phthalic Acid Isomers Research Articles

Biodegradation of phthalic acid and terephthalic acid by Comamonas testosteroni strains.

Phthalic acid isomers are the monomers of phthalate molecules, also known as phthalic acid esters, widely employed in the plastics industry. This study aims to investigate the biodegradation of phthalic acid (PA) and terephthalic acid (TPA) by five industry-borne Comamonas testosteroni strains: 3APTOL, 3ABBK, 2B, 3A1, and C8. To assess the ability of C. testosteroni strains to biodegrade phthalic acid isomers in fermentation media, an analytical method was employed, consisting of high-performance liquid chromatography (HPLC) analyses. Subsequently, molecular screening of the genomic and plasmid DNA was conducted to identify the degradative genes responsible for the breakdown of these chemicals. The genes of interest, including ophA2, tphA2, tphA3, pmdA, and pmdB, were screened by real-time PCR. The five C. testosteroni strains effectively degraded 100% of 100mg/L PA (p = 0.033) and TPA (p = 0.0114). Molecular analyses indicated that all C. testosteroni strains contained the pertinent genes at different levels within their genomes and plasmids, as reflected in the threshold cycle (Ct) values. Additionally, DNA temperature of melting (Tm) analyses uncovered minor differences between groups of genes in genomic and plasmid DNA. C. testosteroni strains could be excellent candidates for the removal of phthalic acid isomers from environmental systems.

High-Definition Differential Ion Mobility Spectrometry with Structural Isotopic Shifts for Anionic Compounds.

Differential ion mobility spectrometry (FAIMS) had emerged in the 2000s as a novel tool for postionization separations in conjunction with mass spectrometry (MS). High-definition FAIMS introduced a decade ago has enabled resolution of peptide, lipid, and other molecular isomers with minute structural variations and recently the isotopic shift analyses where the spectral pattern for stable isotopes fingerprints the ion geometry. Those studies, including all isotopic shift analyses, were in the positive mode. Here, we achieve the same high resolution for anions exemplified by phthalic acid isomers. The resolving power and magnitude of isotopic shifts are in line with the metrics for analogous haloaniline cations, establishing high-definition negative-mode FAIMS with structurally specific isotopic shifts. Different shifts (including the new 18O) remain additive and mutually orthogonal, demonstrating the generality of those properties across the elements and charge states. Expanding to common (not halogenated) organic compounds is a key step toward the broad use of FAIMS isotopic shift methodology.

Biodegradation of diethyl phthalate and phthalic acid by a new indigenous Pseudomonas putida.

Diethyl phthalate (DEP) is one of the extensively used plasticizers which has been considered a priority hazardous pollutant due to its carcinogenic, endocrine disrupter, and multi-toxic effects on humans. The identification of DEP in different parts of the ecosphere has increased the global community's attention to the elimination of this pollutant in a bio-eco-friendly way. In this research, a novel aerobic bacterial strain nominates as ShA (GenBank accession number: MN298858) capable of consuming DEP as carbon and energy sources, was isolated from the upper phase (0-10 cm) of Anzali international wetland sediments by enrichment culture method. Morphological characteristics and 16S rRNA gene sequence analysis demonstrated that strain ShA belonged to Pseudomonas putida. The substrate utilization test demonstrated that strain ShA was able to grow in mineral salt medium containing dimethyl phthalate (DMP) and phthalic acid (PA) isomers including terephthalic and isophthalic acid. Degradation assay showed strain ShA completely degraded 200 mg/L DEP within 22 h (pH 7.0, 30 °C). Surprisingly, PA as the main intermediate of DEP biodegradation was identified by GC-FID. Moreover, the rapid degradation of 2000 mg/L PA to CO2 and H2O was viewed in 22 h by strain ShA. The possible route of DEP degradation was DEP directly to PA and then PA consumption for growth. This study obtained results that provide a great contribution to applying strain ShA in the biodegradation of low molecular weight of PAEs and PA isomers in natural ecosystems. This is the first report of a P. putida strain able to degrade DEP and PA.

Investigation on the structure-performance of phthalic acid carboxyl position and carbon nitride towards efficient photocatalytic degradation of organic pollutants

Polymeric carbon nitride as photocatalysts to address environmental issues attract broad interest. Anchoring aromatic ring on CN surface can improve its charge pair separation, but the effect of functional group position of aromatic ring on its performance is ignored. Herein, we used three isomers of phthalic acid (phthalic acid, isophthalic acid and terephthalic acid) and urea to synthesize modified carbon nitride as a photocatalyst to remove sulfamethazine (SMZ). The phthalic acid may act as group modification and enhanced the absorption of longer wavelengths of carbon nitride, while part of isophthalic acid and terephthalic acid may enter the framework of carbon nitride as benzene ring and the others may act as the amorphous carbon in carbon nitride. Consequently, the phthalic acid modified carbon nitride (PA-CN) exhibited the optimal degradation performance for SMZ removal (0.0737 min−1). It was further revealed that the O2− and h+ played the significant role in the photocatalytic process. This study reveals the effect of the position of organic acid functional groups on the performance of carbon nitride, and points out that PA-CN can be applied to the purification of wastewater containing refractory pollutants.

Assessment of Comamonas testosteroni strain PT9 as a rapid phthalic acid degrader for industrial wastewaters.

In this study, characterization of industry-borne Comamonas testosteroni strain PT9 isolate was performed by determining degradation ability on phthalic acid (PA). High-performance liquid chromatography analyses showed that strain PT9 completely degraded 102.94 mg/L of PA within 6 h. Viability polymerase chain reaction (vPCR) was performed with propidium monoazide treatment. vPCR showed that the PA has positively stimulated the cell growth during degradation. To consider the fate of PA, the proposed catalytic genes (ophA2, iphA2, tphA2, tphA3, pmdA, and pmdB) for the degradation pathways of PA isomers for C. testosteroni were screened in strain PT9. All genes except iphA2 were detected in strain PT9, and expression levels of related genes were analyzed by Real-Time PCR (qPCR).

Microbial degradation of phthalates: biochemistry and environmental implications.

The environmentally relevant xenobiotic esters of phthalic acid (PA), isophthalic acid (IPA) and terephthalic acid (TPA) are produced on a million ton scale annually and are predominantly used as plastic polymers or plasticizers. Degradation by microorganisms is considered as the most effective means of their elimination from the environment and proceeds via hydrolysis to the corresponding PA isomers and alcohols under oxic and anoxic conditions. Further degradation of PA, IPA and TPA differs fundamentally between anaerobic and aerobic microorganisms. The latter introduce hydroxyl functionalities by dioxygenases to facilitate subsequent decarboxylation by either aromatizing dehydrogenases or cofactor-free decarboxylases. In contrast, anaerobic bacteria activate the PA isomers to the respective thioesters using CoA ligases or CoA transferases followed by decarboxylation to the central intermediate benzoyl-CoA. Decarboxylases acting on the three PA CoA thioesters belong to the UbiD enzyme family that harbour a prenylated flavin mononucleotide (FMN) cofactor to achieve the mechanistically challenging decarboxylation. Capture of the extremely instable PA-CoA intermediate is accomplished by a massive overproduction of phthaloyl-CoA decarboxylase and a balanced production of PA-CoA forming/decarboxylating enzymes. The strategy of anaerobic phthalate degradation probably represents a snapshot of an ongoing evolution of a xenobiotic degradation pathway via a short-lived reaction intermediate.

Rheological behavior and mechanism of pH-responsive wormlike micelle variations induced by isomers of phthalic acid.

Responsive wormlike micelles (WLMs) constructed by different carboxylic acids are fascinating. However, it is unknown how the position of the carboxylic groups alters the stimuli-response of wormlike micellar systems. Herein, three pH-responsive WLMs based on Gemini-like surfactants (named o-EAPA, m-EAPA, and p-EAPA) were formed and studied through the complexation of N-erucamidopropyl-N,N-dimethylamine (UC22AMPM) and o-phthalic acid (o-PA), m-phthalic acid (m-PA), or p-phthalic acid (p-PA) at the molar ratio of 2 : 1. The viscoelasticity, phase behavior and aggregate microstructure were separately explored by rheological, appearance observation and cryo-TEM methods. The results show that all phthalic acids can protonate UC22AMPM, thereby forming WLMs. However, with the shorter spacer distance between two carboxyl groups in phthalic acid, o-EAPA exhibits the longer length scale of aggregates and a more efficient thickening ability compared to the other two systems. Similar results in the N,N-dimethyl oleoaminde-propylamine (DOAPA) and o-PA, m-PA, and p-PA systems further verify the applicability of this mechanism. Furthermore, the phthalic acid based WLMs are found to exhibit intriguing reversible pH-responsive behaviors, which include promptly switching between a high elastic system and a low viscosity fluid by pH control. The o-EAPA system possesses a larger viscosity maximum, which produces more precipitous viscosity changes as the pH varies. This study is beneficial for the formation of pH-responsive WLMs and to determine their advantages for applications.

Study on Separation of Structural Isomer with Magneto-Archimedes method

Organic compounds are refined by separating their structural isomers, however each separation method has some problems. For example, distillation consumes large energy. In order to solve these problems, new separation method is needed. Considering organic compounds are diamagnetic, we focused on magneto-Archimedes method. With this method, particle mixture dispersed in a paramagnetic medium can be separated in a magnetic field due to the difference of the density and magnetic susceptibility of the particles. In this study, we succeeded in separating isomers of phthalic acid as an example of structural isomer using MnCl2 solution as the paramagnetic medium. In order to use magneto-Archimedes method for separating materials for food or medicine, we proposed harmless medium using oxygen and fluorocarbon instead of MnCl2 aqueous solution. As a result, the possibility of separating every structural isomer was shown.

Microwave-assisted hydrothermal synthesis of ZnO and Zn-terephthalate hybrid nanoparticles employing benzene dicarboxylic acids

Microwave-assisted hydrothermal synthesis of ZnO nanoparticles employing three isomers of benzene dicarboxylic acids, phthalic acid (PA), isophthalic acid (IPA) and terephthalic acid (TPA) as structure directing agents (SDAs) revealed their strength in the order of TPA > PA > TPA, for the synthesis with solution pH > 10, causing anisotropic crystal growth to result in a variety of specific nanostructures and reduction of particle size. TPA, however, behaved differently from the others when pH was reduced, resulting in a Zn-TPA metal–organic framework (MOF), composed of layered double hydroxide of Zn2+ (Zn LDH) stabilized by the intercalated TPA dianion. Synthesis under controlled pH revealed four different types of Zn-TPA MOFs. Three of them could be isolated to identify their structure and composition by means of XRD, TG–DTA and FT-IR, as Zn3(OH)4(TPA)·6H2O, Zn4(OH)6(TPA) and Zn2(OH)2(TPA)·H2O, with their interlayer distances of 14.4, 10.8 and 9.03 A, as resulted from the syntheses when the initial pH of the precursor solution were adjusted to 7.0, 5.9 and 5.3, respectively. These Zn-TPA MOFs are hitherto unknown, especially for the presence of hydration water and significant change of the interlayer distance, which might have been achieved by the rapid crystallization under microwave radiation.

Micellar and sub-micellar ultra-high performance liquid chromatography of hydroxybenzoic acid and phthalic acid positional isomers

Micellar liquid chromatography (MLC) has been used primarily for the separation of neutral analytes of varying polarities, most commonly phenols and polyaromatic hydrocarbons, but does not seem to have been used to study aromatic hydroxy acids in detail. We have studied the separation of hydroxybenzoic acid mixtures, including monohydroxybenzoic and dihydroxybenzoic acid positional isomers by MLC. Sodium dodecylsulfate (SDS) is investigated as the modifying surfactant on a C18 ultra-high performance liquid chromatography (UHPLC) column (100×2.1mm, 1.8μm). The addition of only SDS (no organic solvent) to the mobile phase reduced the influence of hydrophobic interactions while improving the retention times, resolution, and peak shapes, even at concentrations below the critical micellization concentration (CMC). The UHPLC separation of 7 hydroxybenzoic acids, including 6 dihydroxybenzoic acid positional isomers and one trihydroxybenzoic acid, is achieved with high efficiency using 0.1% SDS in 1.84mM sulfuric acid (pH 2.43) mobile phase, in less than 6min with a flow rate of 0.3mLmin−1, and in less than four min with a flow rate of 0.7mLmin−1. Six monohydroxybenzoic acid isomers are also effectively separated by MLC, using a 0.5% SDS mobile phase modifier, in less than 20min with a flow rate of 0.3mLmin−1, and in less than 14min with a flow rate of 0.7mLmin−1. The 3 phthalic acid isomers could be separated using a similar mobile phase and flow rates in less than 6 and 4min. Solute-micelle equilibrium constants and partition coefficients are calculated for 6 monohydroxybenzoic acids based on a plot of MLC retention factor vs. mobile phase micelle concentration. All aromatic acid isomers studied can be classified as binding solutes in the MLC retention mechanism. Less effective separations are observed with shorter chain surfactants, leading to higher retention times and poor peak shapes. It is concluded that increasing chain length led to more efficient MLC separations, and SDS is the preferred modifying surfactant for the examined separation.

Comparative Cytotoxicity and Sperm Motility Using a Computer-Aided Sperm Analysis System (CASA) for Isomers of Phthalic Acid, a Common Final Metabolite of Phthalates

The general population is exposed to phthalates through consumer products, diet, and medical devices. Phthalic acid (PA) is a common final metabolite of phthalates, and its isomers include isophthalic acid (IPA), terephthalic acid (TPA), and phthalaldehyde (o-phthalic acid, OPA). The purpose of this study was to investigate whether PA and PA isomers exert reproductive toxicity, including altered sperm movement. In vitro cell viability assays were comparatively performed using Sertoli and liver cell lines. In animal experiments, PA or PA isomers (10, 100, or 1000 mg/kg) were administered orally to Sprague-Dawley (SD) rats, and semen samples were analyzed by computer-aided sperm analysis (CASA). PA treatment produced a significant effect on curvilinear velocity (VCL), straight-line velocity (VSL), mean velocity or average path velocity (VAP), amplitude of lateral head displacement (ALH), and frequency of head displacement or beat cross-frequency (BCF), whereas IPA, TPA, and OPA induced no marked effects. In vitro cell viability assays showed that mouse normal testis cells (TM4) and human testis cancer cells (NTERA 2 cl. D1) were more sensitive to PA and OPA than mouse liver normal cells (NCTC clone 1469) and human fetal liver cells (FL 62891). Our study suggests that PA and PA isomers specifically produced significant in vitro and in vivo reproductive toxicity, particularly sperm toxicity and testis cell cytotoxicity. Of the isomers examined, PA appeared to be the most toxic and may serve as a surrogate biomarker for reproductive toxicity following mixed exposure to phthalates.

Solvent vapor effects in planar high-field asymmetric waveform ion mobility spectrometry: Solvent trends and temperature effects

Solvent vapor added to the drift gas in a planar high-field asymmetric waveform ion mobility spectrometer (FAIMS) leads to dramatic shifts to larger CV values while retaining narrow peaks, leading to dramatically increased resolving power (up to ∼140) for a variety of ions including isomeric ions. Here we present studies designed to improve the fundamental understanding of the role of solvent vapor on performance of planar FAIMS, focusing on solvent trends with molecular size and effects of temperature. The studies employ as test compounds the [M−H]− ions of the three positional isomers of phthalic acid and the M− and [M−H]− ions of trinitrotoluene (TNT). The addition of solvent vapor to FAIMS carrier gas has a significant impact on the behavior of the ions inside the FAIMS cell and can impact the overall performance of the cell. We have shown that by comparing a range of solvent vapors (water and C1–C4 alcohols), the magnitude of the effect correlates to the molecular volume of the solvent molecule. This fits well with the model of clustering/declustering of ions with neutral molecules on the time scale of waveform used in FAIMS. We have also shown that with the addition of heat, the effect of the solvent vapor is lessened, as one would expect with the cluster/decluster model.

Electrochemical discrimination of phthalic acid among three phthalic acid isomers based on an N-butylaminomethyl-ferrocene derivative

A chemosensor compound (1) consisting of a central ferrocene with two butylaminomethyl arms showed unexpected facile electrochemical oxidation of the secondary amines in proximity to the ferrocene, which was utilized for electrochemical discrimination of phthalic acid selectively over two other isomers, isophthalic acid and terephthalic acid.

Toxicological Characterization of Phthalic Acid

There has been growing concern about the toxicity of phthalate esters. Phthalate esters are being used widely for the production of perfume, nail varnish, hairsprays and other personal/cosmetic uses. Recently, exposure to phthalates has been assessed by analyzing urine for their metabolites. The parent phthalate is rapidly metabolized to its monoester (the active metabolite) and also glucuronidated, then excreted. The objective of this study is to evaluate the toxicity of phthalic acid (PA), which is the final common metabolic form of phthalic acid esters (PAEs). The individual PA isomers are extensively employed in the synthesis of synthetic agents, for example isophthalic acid (IPA), and terephthalic acid (TPA), which have very broad applications in the preparation of phthalate ester plasticizers and components of polyester fiber, film and fabricated items. There is a broad potential for exposure by industrial workers during the manufacturing process and by the general public (via vehicle exhausts, consumer products, etc). This review suggests that PA shows in vitro and in vivo toxicity (mutagenicity, developmental toxicity, reproductive toxicity, etc.). In addition, PA seems to be a useful biomarker for multiple exposure to PAEs in humans.

Solvent vapor effects on planar high-field asymmetric waveform ion mobility spectrometry

The effects of various concentrations of solvent vapor (either water or methanol) added to the curtain/drift gas in a planar high-field asymmetric waveform ion mobility spectrometer (FAIMS) have been examined. Two different groups of analyte ions (the [M−H] − ions of three positional isomers of phthalic acid and the M − and [M−H] − ions of four explosives: TNT, 2,4 DNT, 2,6 DNT, and 3,4 DNT) were analyzed. Results showed that with the addition of small amounts of solvent vapor (∼1.5% water and 12.3% methanol), there were dramatic shifts to larger CV values for all ions analyzed. There were substantial benefits provided by adding solvent vapor, including dramatically increased resolving power of isomeric ions (up to ∼141). Specifically, analyte ions examined in dried nitrogen exhibited overlapping, undistinguishable CV values, but with large CV shifts afforded by addition of solvent vapor, these analyte ions were completely resolved from one another.

Determination of benzene polycarboxylic acids in atmospheric aerosols and vehicular emissions by liquid chromatography-mass spectrometry

A simple, sensitive and reliable LC-ESI(−)/MS method was developed for determination of selected aromatic dicarboxylic acids (e.g. phthalic acid isomers) and tricarboxylic acids (e.g. trimellitic, trimesic) in atmospheric aerosols and vehicular emissions without complex sample pre-treatment. Gradient liquid chromatographic separation was performed on a Zorbax SB-Aq (150 × 2.1 mm i.d., 3.5 µm) column using a mobile phase consisting of 0.1% formic acid (eluent A) and methanol (eluent B). The Zorbax SB-Aq column was chosen as it was specifically designed to retain highly polar compounds, allowing the use of highly aqueous mobile phases. The method was demonstrated to be sensitive and precise. In the SIM mode, LODs for all target acids dissolved in double deionized water were in the range of 0.03–0.1 µg/L. The method showed a good inter-day precision of retention time (RSD <0.3%) and peak area (RSD <3%). Satisfactory recoveries, ranging from 89 to 107% for the spiked blanks and extracts of real samples, were obtained. The method has been successfully applied to the quantitative analysis of selected benzene polycarboxylic acids in urban atmospheric aerosols and particulate matter emitted from diesel- and gasoline-powered motors. Preliminary results suggest that 3-hydroxyphthalic acid may be used as a potential tracer for diesel engine emissions.

Determination of phthalic, terephthalic, and isophthalic acids in the presence of each other by gas chromatography

A procedure was developed for the simultaneous determination of phthalic acid isomers; the procedure includes the preparation of diisoamyl esters by reaction with isoamyl alcohol in a benzene solution in the presence of sulfuric acid with the distillation of an azeotrope mixture of benzene with water, the neutralization of acid with triethylamine, and the separation of esters by gas-liquid chromatography on a steel column (1 m × 3 mm) filled with Chromaton N-AW-HMDS with 5% Apiezon L in the temperature programming mode with flame-ionization detection. The time of separation is 13 min. The time of the sample preparation step is 2–2.5 h. The lower determination limit is 20 ng. The procedure allows the determination of phthalic acids in the concentration range from 0.02 to 2 mg/L in liquid samples and from 0.03 to 3 mg/m3 in air.

Chromatographic separation for domoic acid using a fragment imprinted polymer

We prepared molecularly imprinted polymers for an amnesic shellfish poison, domoic acid. To prepare the polymer, we tested several commercial aromatic dicarboxylic compounds such as isomers of phthalic acid for templates of molecularly imprinted polymers. The highest selective recognition ability of the polymer for domoic acid in the tested compounds was found when o-phthalic acid was used as the template. The ability was due to the acidity of the carboxylic acids in the domoic acid and the similarity of the shape around the carboxylic acids of domoic acid and the templates. The effective chromatographic separation of domoic acid in the extract from blue mussels was achieved with a LC column packed with the fragment imprinted polymer using o-phthalic acid as the template. This polymer can be utilized for a clean up procedure of domoic acid in toxic shellfish.

CO 2–H 2-dependent anaerobic biotransformation of phthalic acid isomers in sediment slurries

This paper investigates the anaerobic biotransformation of three isomers of phthalic acid and benzoic acid in sediment slurries under four different atmospheres [N 2, N 2/H 2 (19:1, v/v), CO 2, and CO 2/H 2 (4:1, v/v)]. Significant differences were observed in lag periods and biotransformation rates among the phthalic acid isomers and under the different atmospheres. In most cases, the relative biotransformation rates of the three isomers of phthalic acid were ortho-phthalic acid > isophthalic acid > terephthalic acid. Benzoate was transformed faster than any isomer of phthalic acid. Since biotransformation of phthalic acid isomers in sediment slurries was enhanced by high initial levels of H 2 and CO 2 in the headspace, we propose a pathway for phthalic acid biodegradation in which the initial transformation to benzoate is CO 2–H 2 dependent. Acetogenic bacteria were investigated for their possible involvement in this transformation reaction, but when MPN counts were used to compare the growth dynamics of acetogenic bacteria with the time course of the terephthalic acid transformation under N 2/H 2 (19:1, v/v) and CO 2/H 2 (4:1, v/v) atmospheres, the results were inconclusive.

Characterization of polyesters prepared from three different phthalic acid isomers by CID-ESI-FT-ICR and PSD-MALDI-TOF mass spectrometry.

Polyesters prepared from the same diol, 2-butyl-2-ethyl-1,3-propanediol, but different phthalic acid isomers, phthalic, isophthalic, and terephthalic acid, were characterized by collision-induced dissociation electrospray ionization Fourier transform ion cyclotron resonance (CID-ESI-FT-ICR) and postsource-decay matrix-assisted laser desorption/ionization time-of-flight (PSD-MALDI-TOF) mass spectrometry. Sodiated dihydroxyl-terminated polyester oligomers containing five repeating units at m/z 1634 were selected as precursor ions for dissociation studies. Two main mechanisms occurred in the fragmentation of all of the polyesters, since dissociation of the oligomers was initiated by hydrogen rearrangement or transesterification reactions. Polyesters prepared from different phthalic acid isomers could be distinguished by their fragmentation behavior. Polyester prepared from phthalic acid was easily identified by using both CID-ESI-FT-ICR and PSD-MALDI-TOF mass spectrometry. However, distinguishing between the polyesters prepared from isophthalic and terephthalic acid succeeded marginally only with CID-ESI-FT-ICR mass spectrometry. Molecular dynamics calculations were used to obtain an idea of the fragmentation behavior of the polyesters. The low-energy structures of the precursor ions were determined, and the coordination of the oxygen atoms of the polyester oligomers to the sodium cation was examined more closely. Both the experimental and the theoretical studies showed that the sodium ion affinity of polyester changed with the phthalic acid isomer.