Near‐infrared spectra of polyamide 6, poly(vinyl chloride), and polychlorotrifluoroethylene

Araújo, Sérgio Carvalho de; Kawano, Yoshio

doi:10.1002/app.10599

Cited by 14 publications

(5 citation statements)

References 17 publications

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“…Infrared spectral band assignments were first reported in 1956. , Later Kawano and De Araújo revisited , the attributions of the near and mid infrared spectra of PCTFE (see Table ). Their studies on various samples (monomer, liquid, wax, and solid) reveal the presence of at least two chain conformations, with the predominance of one of them in the solid state…”

Section: Synthesis and Homopolymerization Of Chlorotrifluoroethylenementioning

confidence: 99%

(Co)polymers of Chlorotrifluoroethylene: Synthesis, Properties, and Applications

2013

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Section: Synthesis and Homopolymerization Of Chlorotrifluoroethylenementioning

confidence: 99%

(Co)polymers of Chlorotrifluoroethylene: Synthesis, Properties, and Applications

2013

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“…Articles on polymer processing [112][113][114][115] and on polymer characterisation 122,123 are all recent contributions and reveal the interest in the application of NIR spectroscopy in this sector, mainly for process control.…”

Section: Nir Spectroscopy In Brazilmentioning

confidence: 99%

Near Infrared Spectroscopy: fundamentals, practical aspects and analytical applications

Pasquini¹

2003

J. Braz. Chem. Soc.

713

433

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Este trabalho visa prover uma revisão da teoria da Espectroscopia no Infravermelho Próximo (NIR) e das suas aplicações no campo das Ciências Analíticas. Ele é dirigido ao leitor que não possui um conhecimento profundo sobre espectroscopia vibracional mas que gostaria de ser introduzido às potencialidades analíticas desta técnica fascinante e, ao mesmo tempo, se tornar consciente das suas limitações. A teoria fundamental, uma revisão dos instrumentos modernos existentes e aplicações em inúmeros campos, são apresentados. Este trabalho não pretende suprir uma revisão bibliográfica intensiva mas se refere aos materiais recentes mais significativos e representativos encontrados na literatura técnica. Uma vez que este texto foi produzido em conseqüência do primeiro "workshop" em espectroscopia NIR, que ocorreu em Campinas -Brasil, como uma atividade preliminar ao 11º Encontro Nacional de Química Analítica (ENQA), ele também apresenta o estado da arte na Espectroscopia NIR no Brasil, mostrando seus resultados mais recentes e apontando a necessidade de se elevar esta tecnologia a um nível consistente com aquele de suas atividades econômicas. This paper intends to review the basic theory of Near Infrared (NIR) Spectroscopy and its applications in the field of Analytical Science. It is addressed to the reader who does not have a profound knowledge of vibrational spectroscopy but wants to be introduced to the analytical potentialities of this fascinating technique and, at same time, be conscious of its limitations. Essential theory background, an outline of modern instrument design, practical aspects, and applications in a number of different fields are presented. This work does not intend to supply an intensive bibliography but refers to the most recent, significant and representative material found in the technical literature. Because this paper has been produced as consequence of the First Workshop on Near Infrared Spectroscopy, whose venue was Campinas -Brazil, as a pre-conference activity of the XI National Meeting on Analytical Chemistry (ENQA), it also depicts the state of the art of NIR spectroscopy in Brazil, pointing out the current achievements and the need to take the technology to a level consistent with this country's economical activities.

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“…To remove offsets and multiplicative effects, we applied standard normal variate (SNV) preprocessing, ,− ensuring that every spectrum had a standard deviation of one and a mean of zero (Figure S6). Noise was reduced through Savitzky-Golay smoothing (SG) yielding second-derivative spectra (Figures B & S7B) that were subjected to data analysis. − SG smoothing may distort the shape and the intensity of the spectral bands thereby limiting the optimal model performance. − However, preliminary studies and exploratory data analysis were carried out to ensure an optimized outcome. Figure S8 shows the scores of the SNV-only (A) treatment, raw data (B), and SNV plus SG (C) treatment of the sample data.…”

Section: Resultsmentioning

confidence: 99%

Discrimination of Substandard and Falsified Formulations from Genuine Pharmaceuticals Using NIR Spectra and Machine Learning

et al. 2022

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Near-infrared (NIR) spectroscopy is a promising technique for field identification of substandard and falsified drugs because it is portable, rapid, nondestructive, and can differentiate many formulated pharmaceutical products. Portable NIR spectrometers rely heavily on chemometric analyses based on libraries of NIR spectra from authentic pharmaceutical samples. However, it is difficult to build comprehensive product libraries in many low- and middle-income countries due to the large numbers of manufacturers who supply these markets, frequent unreported changes in materials sourcing and product formulation by the manufacturers, and general lack of cooperation in providing authentic samples. In this work, we show that a simple library of lab-formulated binary mixtures of an active pharmaceutical ingredient (API) with two diluents gave good performance on field screening tasks, such as discriminating substandard and falsified formulations of the API. Six data analysis models, including principal component analysis and support-vector machine classification and regression methods and convolutional neural networks, were trained on binary mixtures of acetaminophen with either lactose or ascorbic acid. While the models all performed strongly in cross-validation (on formulations similar to their training set), they individually showed poor robustness for formulations outside the training set. However, a predictive algorithm based on the six models, trained only on binary samples, accurately predicts whether the correct amount of acetaminophen is present in ternary mixtures, genuine acetaminophen formulations, adulterated acetaminophen formulations, and falsified formulations containing substitute APIs. This data analytics approach may extend the utility of NIR spectrometers for analysis of pharmaceuticals in low-resource settings.

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Near‐infrared spectra of polyamide 6, poly(vinyl chloride), and polychlorotrifluoroethylene

Cited by 14 publications

References 17 publications

(Co)polymers of Chlorotrifluoroethylene: Synthesis, Properties, and Applications

(Co)polymers of Chlorotrifluoroethylene: Synthesis, Properties, and Applications

Near Infrared Spectroscopy: fundamentals, practical aspects and analytical applications

Discrimination of Substandard and Falsified Formulations from Genuine Pharmaceuticals Using NIR Spectra and Machine Learning

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