Structural analysis of polychlorinated biphenyls from carbon-13 nuclear magnetic resonance spectra

Egolf, Debra S.; Jurs, Peter C.

doi:10.1021/ac00216a006

Cited by 18 publications

(11 citation statements)

References 80 publications

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“…Muito provavelmente este pico tenha relação somente com insaturações criadas pela degradação do PEG, pois, segundo Egolf, as bifenilas policloradas apresentariam pico em torno de 130 ppm de deslocamento químico. 35 O pico em 76 ppm é referente ao solvente clorofórmio deuterado.…”

Section: Avaliação Dos Resíduos Encontrados Na Fase Polar (Peg)unclassified

Avaliação Dos Resíduos Gerados Durante a Destruição De PCBS Pelo Processo Catalisado Por Base

et al. 2018

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Section: Avaliação Dos Resíduos Encontrados Na Fase Polar (Peg)unclassified

Avaliação Dos Resíduos Gerados Durante a Destruição De PCBS Pelo Processo Catalisado Por Base

et al. 2018

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“…Therefore, a model developed for secondary carbons was used to predict the chemical shifts of the two tertiary carbons, resulting in prediction errors in excess of 50 ppm. These errors severely skewed the results, causing the mean standard error to be greater than that obtained by MOS. In addition, since the tert-butyl carbons in this study were excluded from the model devel- opment procedure, no similar carbon environments existed in the database, and the prediction results for these 12 tert-butyl cycloheptanone carbons were poor. The models selected were reasonable in that they all resided in cyclic ketone structures; however, none of the models were developed with tert-butyl carbons.…”

Section: C=0mentioning

confidence: 99%

“…The creation of a spectral simulation database containing predictive equations for prior simulation studies was recently reported (3). Prior to this study, the database consisted of 66 regression models capable of simulating 13C NMR spectra of linear and branched alkanes (4), cycloalkanes (5), cyclohexanols and decalols (6), hydroxysteroids (7), cyclopentanes and cyclopentanols (8), norbornanols (9), cyclohexanones and decalones (10), piperidines (11), polychlorinated biphenyls (12), alkyl-substituted benzenes and polyaromatics (13), ketosteroids (3), and quinolines and isoquinolines (14). A complete summary of the current model database is shown in supplemental material Table VII.…”

Section: Introductionmentioning

confidence: 99%

Automated model selection for the simulation of carbon-13 nuclear magnetic resonance spectra of cyclopentanones and cycloheptanones

Ball¹,

Anker²,

Jurs³

1991

Anal. Chem.

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Linear equations capable of simulating the carbon-13 nuclear magnetic resonance spectra of cyclopentanones and cycloheptanones are developed. The equations relate structural descriptors to 1íC NMR chemical shifts. These descriptors encode the topological, geometrical, and electronic environment surrounding each carbon atom. Due to the conformational flexibility of these compounds, the significance of the geometrical descriptors, In particular, was evaluated. When used together, the models can simulate the chemical shifts of the 36-compound data set with an average spectral error of 1.12 ppm. The models are now Included In a spectral simulation database containing 71 predictive equations. This study also Involves enhancing the existing model database and the automated model selection procedure used to probe the database. The new model selection scheme determines model suitability based on a similarity measure between a query carbon and all of the carbon atoms used to develop the database models In previous studies. This enhancement dramatically Improves the prediction results for an eightcompound external prediction set containing cyclopentanones and cycloheptanones.

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“…Therefore, all holders of electrical equipment should determine whether their equipment contains PCBs or verify the absence of PCBs. Although the quantification of PCBs in electrical transformers may seem simple, the diversity of congeners, as well as their similar physical and chemical properties makes PCBs difficult compounds to analyses based on the limited information presently gathered and published in the scientific literature [9]. In order to determine potential threats, identify the probability of occurrence and the potential impact to public and environmental health, transformers that come out of service must sampled and analyzed.…”

Section: Introductionmentioning

confidence: 99%

Transformer Oils Potential for PCBs Contamination

Pelitli¹,

Dogan²,

Köroğlu³

2015

Int J Metall Mater Eng

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Polychlorinated biphenyls (PCBs) are a class of synthetic organic chemicals consisting of from one to ten chlorine atoms bonded totwo phenyl rings that create up 209 possible variations referred to as congeners. PCBs were commercially produced world-wide on a large scale between the 1930s and 1980sthat had been used widely in variety of commercial equipment like transformers, capacitors and other electrical equipment because of their useful quality as being a fire retardant. But due to their persistence and ubiquitous distribution in the environment, PCBs were banned from the U.S in the 1970s and internationally through the Stockholm Convention on Persistent Organic Pollutants. Although banned by law and punished heavily, large numbers of PCB-contaminated transformers are still in service. Thus, there remains a huge reservoir of PCBs with the potential to serve as sources of contamination to the environment. In this study, using EN 12766 test method: "Petroleum products and used oils-Determination of PCBs and related products", PCBs were analyzed in the random samples collected from different regions of Turkey. The samples also used for screening for the presence of total halogens and chlorine. Test results of the study showed that PCBs were present in certain transformers but concentrations in the most of samples did not exceed the limit value of 50 ppm.However, there was a significant relationship between the PCB concentrationsand the halogens.Finally, the contaminated transformer oils were evaluated according to Regulation on Control ofWaste Oils.

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Structural analysis of polychlorinated biphenyls from carbon-13 nuclear magnetic resonance spectra

Cited by 18 publications

References 80 publications

Avaliação Dos Resíduos Gerados Durante a Destruição De PCBS Pelo Processo Catalisado Por Base

Avaliação Dos Resíduos Gerados Durante a Destruição De PCBS Pelo Processo Catalisado Por Base

Automated model selection for the simulation of carbon-13 nuclear magnetic resonance spectra of cyclopentanones and cycloheptanones

Transformer Oils Potential for PCBs Contamination

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