O-phenylphenol Research Articles

Comparison of Current-Use Pesticide and Other Toxicant Urinary Metabolite Levels among Pregnant Women in the CHAMACOS Cohort and NHANES

BackgroundWe measured 34 metabolites of current-use pesticides and other precursor compounds in urine samples collected twice during pregnancy from 538 women living in the Salinas Valley of California, a highly agricultural area (1999–2001). Precursors of these metabolites included fungicides, carbamate, organochlorine, organophosphorus (OP), and pyrethroid insecticides, and triazine and chloroacetanilide herbicides. We also measured ethylenethiourea, a metabolite of the ethylene-bisdithiocarbamate fungicides. Repeat measurements of the compounds presented here have not been reported in pregnant women previously. To understand the impact of the women’s regional environment on these findings, we compared metabolite concentrations from the CHAMACOS (Center for the Health Assessment of Mothers and Children of Salinas) cohort with U.S. national reference data for 342 pregnant women sampled by the National Health and Nutrition Examination Survey (1999–2002).ResultsThe eight metabolites detected in > 50% of samples [2,4-dichlorophenol (2,4-DCP); 2,5-dichlorophenol (2,5-DCP); 1- and 2-naphthol; ortho-phenylphenol (ORTH); para-nitrophenol (PNP); 2,4,6-trichlorophenol (2,4,6-TCP); and 3,4,6-trichloro-2-pyridinol (TCPy)] may be related to home or agricultural pesticide use in the Salinas Valley, household products, and other sources of chlorinated phenols. More than 78% of women in this study had detectable levels of at least one of the OP pesticide-specific metabolites that we measured, and > 30% had two or more. The 95th percentile values of six of the most commonly detected (> 50%) compounds were significantly higher among the CHAMACOS women after controlling for age, race, socioeconomic status, and smoking [(2,4-DCP; 2,5-DCP; ORTH; PNP; 2,4,6-TCP; and TCPy); quantile regression p < 0.05].ConclusionsFindings suggest that the CHAMACOS cohort has an additional burden of precursor pesticide exposure compared with the national sample, possibly from living and/or working in an agricultural area.

Induction of systemic resistance and management of safflower Macrophomina phaseolina root-rot disease by biocontrol agents

Three biocontrol agents such as Trichoderma harizianum, Pseudomonas fluorescens and Bacillus subtilis were isolated from safflower rhizosphere soil and tested individually for their effectiveness in controlling root-rot of safflower. Talc based formulations were prepared and treated the seeds at different concentrations for assessing their ability to induce plant growth and in turn control root-rot disease. Among bioagents, P. fluorescens and T. harzianum (10 g/kg) proved to be effective in controlling disease under laboratory, greenhouse and field conditions. The efficacy of these biocontrol agents are equivalent to the standard fungicide Bavistin (Carbedazim). Other than direct action of these biocontrol agents triggered defense related enzymes involved in phenyl proponoid pathways and phenols. Higher activity of peroxidase, phenylalanine ammonia-lyase, chitinase, polyphenol oxidase and β-1,3-glucanase was observed in P. fluorescens and T. harzianum treated safflower plants after challenge inoculation with M. phaseolina. Seed treatment with these biocontrol agents enhanced the seed germination and growth parameters against root-rot disease and they also induced systemic resistance and/or physiological changes leading to plant defense mechanisms.

Rapid determination of five post-harvest fungicides and metabolite in citrus fruits by liquid chromatography/time-of-flight mass spectrometry with atmospheric pressure photoionization

Liquid chromatography/time-of-flight mass spectrometry (LC/TOF-MS) with atmospheric pressure photoionization (APPI) has been used for the determination of five post-harvest fungicides and metabolite, o-phenylphenol (OPP), diphenyl (DP), thiabendazole (TBZ), imazalil (IMZ), and its major metabolite R14821 (IMZ-M) in citrus fruits. Samples were extracted with diethyl ether and the extracts with minimal sample preparation were analyzed by LC/TOF-MS with APPI by measuring accurate mass. DP, IMZ, and IMZ-M were ionized in positive ion mode, and OPP and TBZ were in negative ion mode. The recoveries fortified to citrus fruits at 1 μg/g ranged from 70.5% to 101.4%. The detection limits (S/N = 3) were 0.002 μg/g (OPP, TBZ, and IMZ-M), 0.001 μg/g (IMZ), and 0.03 μg/g (DP).

Preparation of Highly Active Pt-K/γ-Al2O3 Catalyst for o-Phenylphenol Synthesis from o-Cyclohexenyl-cyclohexanone Dehydrogenation

0.5%Pt-K/γ-Al2O3 catalysts for the synthesis of o-phenylphenol(OPP) from o-cyclohexenyl-cyclohexanone (dimer) dehydrogenation were prepared by means of a two subsequent impregnation method. The effects of catalyst preparation parameters, such as K promoters, calcination, and reduction conditions, were investigated. The results showed that the addition of K2SO4 to Pt/γ-Al2O3 catalyst notably promoted the selectivity of OPP, and its optimum content was found to be 6% in mass fraction. The higher activity was obtained when Pt/γ-Al2O3 catalyst was calcined in nitrogen atmosphere at 400—500 °C and then reduced at the same temperature for 3 h in hydrogen atmosphere. The conversion of the dimer and the selectivity of OPP were always above 99% and 90%, respectively, over 0.5%Pt-6% K2SO4/γ-Al2O3 catalyst during the pilot scale test of 8000 h.

Induction of mitosis delay, apoptosis and aneuploidy in human cells by phenyl hydroquinone, an Ames test-negative carcinogen

Ortho-phenyl phenol and its hepatic derivative, phenyl hydroquinone, do not generate base-substitution-type mutations, but cause bladder cancer in rats and mice. The mechanism of their carcinogenic effect is unknown. We have previously shown that o-phenyl phenol and phenyl hydroquinone induce mitotic arrest and aneuploidy in Saccharomyces cerevisiae. To further delineate the mechanism of action of phenyl hydroquinone, we examined its effect on human cells. Treatment of the colon cancer cell line HCT116 with 0 to 150 microM phenyl hydroquinone caused a concentration-dependent inhibition of growth, accumulation of cells having G2/M DNA content, and an increase in the mitotic index. Moreover, a dose-dependent increase in apoptotic cells was observed. Finally, a high frequency of aneuploid cells was found. On the other hand, no increase in gamma-H2AX foci was observed. The results show that phenyl hydroquinone does induce mitotic arrest, apoptosis and aneuploidy in the absence of DNA damage. Our results may be useful to understand the mechanisms of action of chemical substances that are Ames test-negative carcinogens.

Mass flows of endocrine disruptors in the Glatt River during varying weather conditions

This study focused on the occurrence and behaviour in wastewater and surface waters of several phenolic endocrine disrupting compounds (EDCs) including parabens, alkylphenolic compounds, phenylphenol (PhP) and bisphenol A (BPA). Analytical procedures using solid-phase-extraction and LC-MS/MS techniques were applied to samples of influents and effluents of wastewater treatment plants (WWTPs) discharging into the Glatt River (Switzerland) as well as to river water samples. A mass flow analysis provided insight into the main sources and the fate of these contaminants during different weather conditions. Concentrations in influents were in the low μg/L range for most analytes. Removal of parabens in the WWTPs was mostly above 99%. Nonylphenol polyethoxylates (A 9PEO) removal amounted to 98%, but in some cases nonylphenoxy acetic acid (A 9PEC) or nonylphenols (NP) were formed. In effluents, concentrations were highest for the A 9PEC, A 9PEO and NP. Concentrations in river water were in the high ng/L range for alkylphenolic compounds and in the low ng/L range for BPA, PhP and the parabens. During the sampling period, in which several rain events occurred, both water flows and mass flows varied strongly. Mass flows in WWTP effluents and in the river increased with increasing water flows for most compounds indicating that higher water flows do not lead necessarily to a proportional dilution of the pollutants. Throughout the low water flow period, mass flows predicted from the known inputs were similar to the actual mass flows at the end of the river for most analytes. For none of the EDCs, significant in-stream removal could be observed. In the periods with high water flows, mass flows in the river were much higher than can be explained by the initially defined sources. Discharge of untreated wastewater influent into the river was assessed as an additional source. Adding this source improved the mass balance for some, but not all of the analytes.

Toxicogenomic response of Pseudomonas aeruginosa to ortho-phenylphenol.

BackgroundPseudomonas aeruginosa (P. aeruginosa) is the most common opportunistic pathogen implicated in nosocomial infections and in chronic lung infections in cystic fibrosis patients. Ortho-phenylphenol (OPP) is an antimicrobial agent used as an active ingredient in several EPA registered disinfectants. Despite its widespread use, there is a paucity of information on its target molecular pathways and the cellular responses that it elucidates in bacteria in general and in P. aeruginosa in particular. An understanding of the OPP-driven gene regulation and cellular response it elicits will facilitate more effective utilization of this antimicrobial and possibly lead to the development of more effective disinfectant treatments.ResultsHerein, we performed a genome-wide transcriptome analysis of the cellular responses of P. aeruginosa exposed to 0.82 mM OPP for 20 and 60 minutes. Our data indicated that OPP upregulated the transcription of genes encoding ribosomal, virulence and membrane transport proteins after both treatment times. After 20 minutes of exposure to 0.82 mM OPP, genes involved in the exhibition of swarming motility and anaerobic respiration were upregulated. After 60 minutes of OPP treatment, the transcription of genes involved in amino acid and lipopolysaccharide biosynthesis were upregulated. Further, the transcription of the ribosome modulation factor (rmf) and an alternative sigma factor (rpoS) of RNA polymerase were downregulated after both treatment times.ConclusionResults from this study indicate that after 20 minutes of exposure to OPP, genes that have been linked to the exhibition of anaerobic respiration and swarming motility were upregulated. This study also suggests that the downregulation of the rmf and rpoS genes may be indicative of the mechanism by which OPP causes decreases in cell viability in P. aeruginosa. Consequently, a protective response involving the upregulation of translation leading to the increased synthesis of membrane related proteins and virulence proteins is possibly induced after both treatment times. In addition, cell wall modification may occur due to the increased synthesis of lipopolysaccharide after 60 minutes exposure to OPP. This gene expression profile can now be utilized for a better understanding of the target cellular pathways of OPP in P. aeruginosa and how this organism develops resistance to OPP.

Microarray analysis of toxicogenomic effects of Ortho-phenylphenol in Staphylococcus aureus

BackgroundStaphylococcus aureus (S. aureus), is responsible for many infectious diseases, ranging from benign skin infections to life-threatening endocarditis and toxic shock syndrome. Ortho-phenylphenol (OPP) is an antimicrobial agent and an active ingredient of EPA-registered disinfectants with wide human exposure in various agricultural, hospital and veterinary disinfectant products. Despite many uses, an understanding of a cellular response to OPP and it's mechanism of action, targeted genes, and the connectivity between targeted genes and the rest of cell metabolism remains obscure.ResultsHerein, we performed a genome-wide transcriptome analysis of the cellular responses of S. aureus when exposed to 0.82 mM of OPP for 20 and 60 min. Our data indicated that OPP downregulated the biosynthesis of many amino acids, which are required for protein synthesis. In particular, the genes encoding the enzymes of the diaminopimelate (DAP) pathway which results in lysine biosynthesis were significantly downregualted. Intriguingly, we revealed that the transcription of genes encoding ribosomal proteins was upregulated by OPP and at the same time, the genes encoding iron acquisition and transport were downregulated. The genes encoding virulence factors were upregulated and genes encoding phospholipids were downregulated upon 20 min exposure to OPP.ConclusionBy using microarray analysis that enables us to simultaneously and globally examine the complete transcriptome during cellular responses, we have revealed novel information regarding the mode of action of OPP on Staphylococcus: OPP inhibits anabolism of many amino acids and highly downregulates the genes that encode the enzymes involved in the DAP pathway. Lysine and DAP are essential for building up the peptidoglycan cell wall. It was concluded that the mode of action of OPP is similar to the mechanism of action of some antibiotics. The discovery of this phenomenon provides useful information that will benefit further antimicrobial research on S. aureus.

Presence of the biocide ortho-phenylphenol in canned soft drinks in the United States and Germany

Canned soft drink samples obtained from the United States and from Germany were analyzed for the biocidal (and potentially carcinogenic) compound ortho-phenylphenol (OPP). Sampling locations were Baltimore (Maryland), Yonkers (New York), Pasadena (California), and Munich (Germany). OPP was detected in 49 out of the 55 samples analyzed, with concentrations generally at the μg/l level. The highest OPP value was measured at 16.9 μg/l in a lemon flavored cola. A mean concentration of 2.9 μg/l was computed for OPP in all samples, assuming values of zero for those samples in which OPP was not detected. OPP was detected in soft drinks obtained from all regions sampled, suggesting that contamination of canned beverages by OPP may be a widespread phenomenon.

Automated on-line column-switching HPLC-MS/MS method with peak focusing for measuring parabens, triclosan, and other environmental phenols in human milk

Parabens (esters of p-hydroxybenzoic acid) and triclosan are widely used as preservatives and antimicrobial agents, respectively, in personal care products, pharmaceuticals, and food processing. Because of their widespread use and potential risk to human health, assessing human exposure to these compounds in breastfed infants is of interest. We developed a sensitive method, using a unique on-line solid-phase extraction-high performance liquid chromatography-tandem mass spectrometry system with peak focusing feature, to measure in human milk the concentrations of five parabens (methyl-, ethyl-, propyl-, butyl-, and benzyl parabens), triclosan, and six other environmental phenols: bisphenol A (BPA); ortho-phenylphenol (OPP); 2,4-dichlorophenol; 2,5-dichlorophenol; 2,4,5-trichlorophenol; and 2-hydroxy-4-methoxybenzophenone (BP-3). The method, validated by use of breast milk pooled samples, shows good reproducibility (inter-day coefficient of variations ranging from 3.5% to 16.3%) and accuracy (spiked recoveries ranging from 84% to 119% at four spiking levels). The detection limits for most of the analytes are below 1 ng mL −1 in 100 μL of milk. We tested the usefulness of the method by measuring the concentrations of these twelve compounds in four human milk samples. We detected methyl paraben, propyl paraben, triclosan, BPA, OPP, and BP-3 in some of the samples tested. The free species of these compounds appear to be the most prevalent in milk. Nevertheless, to demonstrate the utility of these measures for exposure and risk assessment purposes, additional data about sampling and storage of the milk, and on the stability of the analytes in milk, are needed.

ＧＣ／ＭＳによる農産物中のジフェニルおよびオルトフェニルフェノールの分析

A simple determination method of diphenyl (DP) and o-phenylphenol (OPP) in agricultural products by GC/MS was examined. DP and OPP were extracted with ethyl acetate in the presence of anh. sodium sulfate. After addition of n-butanol, the extract solution was concentrated. Clean-up was achieved by shaking with graphitized bulk carbon (Supelclean ENVI-Carb). Addition of polyethylene glycol sharpened the OPP peak on GC/MS analysis. The recoveries from 9 kinds of agricultural products spiked at 0.01 and 0.5 microg/g each were mostly in the range of 70 to 120%, except for 50% recovery of OPP from barley spiked at 0.01 microg/g. The quantification limits (S/N > or =10) of DP and OPP were 0.0013 and 0.005 microg/g (0.0025 and 0.01 microg/g in barley and soybean), respectively.

Ames test-negative carcinogen, ortho-phenyl phenol, binds tubulin and causes aneuploidy in budding yeast

Ortho-phenyl phenol (OPP) is broad-spectrum of fungicides and antibacterial agents. OPP tested negative in an Ames system and positive with respect to the formation of tumors in the urinary bladder in rats when administered in diet, showing attributes of an Ames test-negative carcinogen. It has also been demonstrated that OPP does not bind or cleave DNA in vivo or in vitro, rather dose-dependent protein binding in OPP-treated rats was observed. OPP, however, generates chromosomal aberrations including aneuploidy. Thus, the steps by which Ames test-negative carcinogens exert their effects need to be elucidated. Here, we used an assay of loss of heterozygosity (LOH) in Saccharomyces cerevisiae to determine the biological effects of OPP and its hepatic metabolite phenyl hydroquinone (PHQ). LOH was found to be induced by OPP and PHQ because of a functional chromosome loss: aneuploidy. PHQ bound to and interfered with the depolymerization of tubulin in vitro and arrested the cell-cycle at M and G1. These results indicate that OPP and PHQ damaged tubulin to cause mis-segregation of chromosome by delaying cell-cycle progression through mitosis, and as a consequence caused aneuploidy.

PROBLEMS OF POSITIVE LIST SYSTEM REVEALED BY SURVEY OF PESTICIDE RESIDUE IN FOOD

The positive list system became effective from May 29, 2006 to improve the regulation of residual agricultural chemicals (pesticides, feed additives and veterinary drugs) in foods. In accordance with the system, we investigated pesticide residues in 50 agricultural products purchased in Morioka city from March to November 2006. Analyses were performed according to the "Multiresidue Method for Agricultural Chemicals by GC/MS", the Notice of the Ministry of Health, Labour and Welfare. Five pesticides and two non-agricultural chemicals were detected from 16 samples. Ortho-phenylphenol (OPP) was detected from 8 samples: immature pea, snap bean, kiwi, plain-boiled bamboo shoot, mango, white asparagus, lemon and domestic shiitake mushroom. Maximum residue limits (MRLs) have not been established for these products, and they exceeded the uniform level of 0.01 ppm. DDT was detected from Philippines banana (0.30 ppm) and Korean paprika (0.45 ppm). The residual level in Philippines banana was lower than the MRL, but Korean paprika exceeded its MRL. Chlorpyrifos, Thiabendazole and Imazaril were detected from citrus imported from the U.S.A., but their residue levels were lower than the respective MRLs. Aniline and 2-pyrrolidone were detected from several imported products. These two may not be regulated by the positive list system because they are not agricultural chemicals, although their derivatives are used as pesticides or veterinary drugs. Three problems have been revealed from this survey: 1) application of the uniform level to minor agricultural products, 2) residues of non-agricultural chemicals whose toxicity is uncertain, 3) metabolites of agricultural chemicals, which are also regulated by the positive list system, have not been clearly defined.

Development of a new E. coli strain to detect oxidative mutation and its application to the fungicide o-phenylphenol and its metabolites

Oxidative mutation is mainly induced by reactive oxygen species (ROS), such as the superoxide anion radical (O 2 −) and hydrogen peroxide (H 2O 2). However, in Escherichia coli ( E. coli), ROS are eliminated by enzymes such as superoxide dismutase and catalase, which are coded by sodAB and katEG genes. In this study, to detect mutagens that induce oxidative mutation, a mutant (WP2 katEGsodAB) with katEG and sodAB deleted was constructed by gene manipulation of E. coli WP2. H 2O 2 and menadione sodium bisulfite generated mutation in WP2 katEGsodAB but not in WP2. o-Phenylphenol (OPP) and its metabolites (phenylhydroquinone (PHQ) and phenyl-1,4-benzoquinone (PBQ)), which had been shown to be negative in the Ames test but reported to be carcinogenic, induced mutation in WP2 katEGsodAB but not in WP2. These results suggest that the new assay may be useful for the detection of oxidative mutagens.

Liquid phase cyclohexylation of phenol with cyclohexene using 12-tungstosilicicacid supported onto different supports

Alkylation of phenol with cyclohexene as an alkylating agent was carried out in liquid phase by varying different parameters such as temperature, time, mole ratio of phenol to cyclohexene and amount of the catalyst over 30% 12-tungstosilicicacid supported onto hydrous zirconia and neutral alumina. The present catalysts show high activity towards the %conversion and %selectivity, especially for 2-cyclohexyl phenol, an important product used as intermediate in dyestuff preparation as well as in preparation of 2-phenyl phenol which is used as disinfectant and fungicides.

Simple and Sensitive Determination of o-Phenylphenol in Citrus Fruits Using Gas Chromatography with Atomic Emission or Mass Spectrometric Detection

In this work, a simple and sensitive method for the analysis of the pesticide o-phenylphenol (OPP) on citrus fruits was developed. OPP is extracted with dichloromethane by ultrasonication and derivatized with ferrocenecarboxylic acid chloride. Using ferrocene as a label, residues of OPP are determined by gas chromatography with atomic emission detection in the iron selective mode or with mass spectrometric detection. Sample cleanup is simple and rapid and merely involves a removal of excess reagent on an alumina minicolumn. The method detection limit is 2 ng of OPP/g of fruit, and recoveries from lemon samples fortified at levels of 35 and 140 ng/g are 101 and 106%, respectively. The citrus fruits analyzed (oranges, grapefruits, lemons) contained between 60 ng/g and 0.37 microg/g OPP (RSD = 8-13%), and the results were in good agreement with results obtained when OPP was analyzed using an established HPLC-FLD method. Several alcohols could also be identified in the fruit peel.

Micronuclei and cell proliferation as early biological markers of ortho-phenylphenol-induced changes in the bladder of male F344 rats

ortho-Phenylphenol (OPP) and its sodium salt, sodium ortho-phenylphenate (SOPP), are widely used fungicides and antibacterial agents known to cause tumors in the bladders of male F344 rats. Previous studies in our laboratory have shown that micronuclei and cell proliferation were induced in the bladders of treated rats by a high dose of OPP. In our present studies, we investigated the relationship in dose response between these two biomarkers and previously reported tumor formation in the bladders of male F344 rats. Significant non-linear increases in micronuclei (MN) and BrdU-labeling were seen in the bladder cells of rats treated with the 8000 and 12,500 ppm doses of OPP and at 20,000 ppm SOPP. CREST anti-kinetochore staining showed that the micronuclei originated from both chromosomal loss and breakage. In addition, increases in MN were detected in the bladder but not in the bone marrow, underscoring the value of assessing genotoxicity in the target organ. In summary, these studies clearly show that at high doses, OPP and SOPP are genotoxic to the rat bladder. These results also indicate that micronucleus formation and cell proliferation can detect early OPP-induced changes in the rat bladder and may be useful as biomarkers for bladder carcinogens.

Measuring environmental phenols and chlorinated organic chemicals in breast milk using automated on-line column-switching–high performance liquid chromatography–isotope dilution tandem mass spectrometry

Breast milk is one possible route of exposure to environmental chemicals, including phenols and chlorinated organic chemicals for breast-fed infants. We developed a highly sensitive method of analyzing breast milk for triclocarban (3,4,4'-trichlorocarbanilide) and eight phenolic compounds: bisphenol A (BPA), 4-tert-octylphenol (4-tOP), ortho-phenylphenol (OPP), 2,4-dichlorophenol, 2,5-dichlorophenol, 2,4,5-trichlorophenol, 2,4,6-trichlorophenol, and 2-hydroxy-4-metoxybenzophenone (BP-3). The method includes adding a solution containing a stable isotope of each chemical, enzymatic hydrolysis of the conjugated chemicals in the milk, and on-line solid-phase extraction coupled with high performance liquid chromatography-tandem mass spectrometry. It can also be used to measure the free (unconjugated) species by omitting the enzymatic deconjugation step. The method, validated using pooled breast milk samples, has inter-day coefficient of variations ranging from 4.8 to 18.9% for most analytes, and spiked recoveries generally about 100%. Detection limits for most analytes are below 1 ng/mL in 100 microL of breast milk. We tested the usefulness of the method by measuring concentrations of these nine compounds in 20 breast milk samples. BPA, OPP, and BP-3 were detected in more than 60% of the samples tested. The free species of these compounds appear to be most prevalent in milk.

Synthesis, characterization, and hyperpolarizability measurements of main‐chain azobenzene molecules

AbstractA series of new AB type azobenzene monomers based on various substituted phenols and higher order fused/extended aromatic rings were synthesized and their hyperpolarizability tensor β determined by hyper‐Rayleigh scattering (HRS) measurement in methanol. The electron donor (OH) and acceptor units (COOH) were kept constant in the series, but the effective conjugation length was varied by varying the number and position of substituents as well as the number of aromatic rings. The effect of substitution of the phenolic ring on the β value was investigated and it was found to range from 15 × 10−30 to 42 × 10−30 esu. The effect of intramolecular hydrogen bonding on the nonlinear optical (NLO) property was also examined. The nonlinearity was in the following order of phenol derivative: α‐naphthol &gt; phenyl phenol &gt; 2,6‐dimethyl phenol &gt; o‐cresol &gt; cardanol &gt; phenol &gt; β‐naphthol. The unusually low values for the β‐naphthol‐based chromophore compared with its isomer (α‐naphthol) could be rationalized based on hydrogen bonding of the o‐hydroxyl group with the β nitrogen of the azo bridge. These azobenzene NLO chromophoric monomers were polymerized to form main‐chain polymers with a head to tail structure. The polymers had high thermal stability and rather low solubility in common organic solvents. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4455–4468, 2005

Comparison of Photooxidation and Thermal Oxidation Processes in Poly(ether imide)

Thermal oxidation and photooxidation processes occurring in poly 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride−1,3-phenylendiamine copolymer (ULTEM), were investigated and compared. The study aimed at finding possible differences in the oxidation pathways of this complex polymer by using the analytical power of MALDI techniques. ULTEM films were subjected to photooxidation by exposure at 60 °C in a UV accelerated chamber (Q-UV Panel) in atmospheric air, and the oxidative process was followed as a function of the exposure time. Relevant structural information on the photooxidized ULTEM species was extracted from the MALDI spectra. These data show the presence of polymer chains containing acetophenone, phenyl acetic acid, phenols, benzoic acid, phthalic anhydride, and phthalic acid end groups. The mechanisms accounting for the formation of photooxidation products of Ultem involve several reactions: (i) photocleavage of methyl groups of the N-methyl phthalimide terminal units; (ii) photooxidati...