Quantitative infrared spectroscopic

Allara D L and Nuzzo R G 1985 Spontaneously organized molecular assemblies. 2. Quantitative infrared spectroscopic determination of equilibrium structures of solution-adsorbed normal-alkanoic acids on an oxidized aluminum surface Langmuir 1 52-66... 

K Russell, DC Cole, FM McLaren, DE Pivonka. Analytical techniques for combinatorial chemistry quantitative infrared spectroscopic measurements of deuterium-labeled protecting groups. J Am Chem Soc 118 7941-7945, 1996. 

Quantitative infrared spectroscopic analysis can be carried out on blood serum to determine the relative amounts of lipid that are present. Triglycerides, phospholipids and cholesteryl esters are the classes of lipid which occur in blood serum. These compounds occur naturally in concentrations which make infrared analysis attractive, and the necessary preliminary separation is simple. These classes of compounds can be characterised using infrared spectroscopy by their carbonyl bands. The peak maxima are as follows ... 

Allara, D. L., and Nuzzo, R. G. (1985) Spontaneously Organized Molecular Assemblies. 2. Quantitative Infrared Spectroscopic-Determination of Equillibrium Structures of Solution-Adsorbed n-Alkanoic Acids on an Oxidized Aluminum Surface, Langmuir 1, 52-66. 

Kleeberg H, Klein D, Luck WAP (1987) Quantitative infrared spectroscopic investigations of hydrogen-bond cooperativity. J Phys Chem 91(12) 3200-3203. doi 10.1021/jl00296a019... 

W. Kimmer, Quantitative Infrared Spectroscopic Analysis of Multicomponent Systems, Jena Rev, 50, 5, 166-170, 1960. 

Analysis for the purpose of accurately determining the quantity of a chemical species existing in a sample is called quantitative analysis. Quantitative infrared spectroscopic analysis mainly deals with the intensity of an infrared absorption band. In this chapter, basic aspects of quantitative spectroscopic infrared analysis for a target substance (the analyte) in solution samples are described. The subjects to be described include the characteristics of a Fourier transform infrared (FT-IR) spectrometer, the relation between percentage transmittance and absorbance, Lambert-Beer s law on the relationship between the intensity of an infrared band and the concentration of a sample, the use of a working curve in quantitative analysis, and the origins of deviations from Lambert-Beer s law. 

Quantitative infrared spectroscopic analysis is based on Beer s law that directly relates the concentration of an analyte (target of analysis) in a sample solution with the intensity (in absorbance) of an absorption band of the analyte [1], As Beer s law, which can be derived from Maxwell s equations, is physically established, a reliable model for quantitative analysis can be built on it. 

In addition to these problems in applying the single-band method to quantitative infrared spectroscopic analysis, the single-band method is not suitable for determining the molar ratios of two or more substances existing in a sample. The single-band method, which depends only on the selected key band, does not utilize all the other bands in the observed infrared spectrum. Thus, it is reasonable to seek an alternative method that makes the optimum use of an entire infrared absorption spectrum for quantitative analysis. 

Chemometrics [2-6], a suite of the multivariate data analyses techniques, has been developed to overcome the hmitations of the single-band method. These techniques utilize all the infrared absorption bands over a wide wavenumber region as multivariate data for quantitative analysis, and can handle multicomponent samples simultaneously. In other words, the methods of chemometrics in quantitative infrared spectroscopic analysis are mathematical procedures to apply the concept of Beer s law to various problems in order to extract from them as much usefiil information as possible. In this chapter, the term spectroscopic calibration or just calibration is used to represent such procedures. 

By expressing spectral information and component data as vectors, all the scalar parameters in Beer s law are now replaced by a matrix equation A = CK. This relation can accommodate any number of chemical components by altering the matrix size. The matrix formulation is thus the basis for quantitative infrared spectroscopic analysis. In practice, however, this equation does not hold strictly, because most of the observed data contain uncertain factors such as noise. To remove the uncertain factors from A, a matrix composed of the uncertain factors is introduced. This matrix, which is denoted by R, is called the residual matrix (or error matrix). Then, the equation is rewritten as... 

Perhaps the most revolutionary development has been the application of on-line mass spectroscopic detection for compositional analysis. Polymer composition can be inferred from column retention time or from viscometric and other indirect detection methods, but mass spectroscopy has reduced much of the ambiguity associated with that process. Quantitation of end groups and of co-polymer composition can now be accomplished directly through mass spectroscopy. Mass spectroscopy is particularly well suited as an on-line GPC technique, since common GPC solvents interfere with other on-line detectors, including UV-VIS absorbance, nuclear magnetic resonance and infrared spectroscopic detectors. By contrast, common GPC solvents are readily adaptable to mass spectroscopic interfaces. No detection technique offers a combination of universality of analyte detection, specificity of information, and ease of use comparable to that of mass spectroscopy. 

CD, Rocking Modes as Quantitative Fourier Transform Infrared Spectroscopic Probes of Conformational Disorder in Phospholipid Bilayers... 

Infrared spectroscopy is an important technique for studying acidity. Acidic OH groups can be studied directly. Probe molecules such as pyridine may be used to study both Bronsted and Lewis acidity since two forms of adsorbed probes are easily distinguished by their infrared spectra. Quantitative infrared spectroscopy may be performed by measuring the spectrum of acidic OH or probes adsorbed on thin, self-supporting wafers of the acidic solid. Other spectroscopic methods which may provide information in specific cases include Fourier Transform Raman spectroscopy, electron spin resonance spectroscopy, ultraviolet spectroscopy, and nuclear magnetic resonance spectroscopy. 

Imaging studies were done on copolymers prepared by the polymer modification route because of the availability of the precursor polymers of various molecular weights. The protected copolymers were compounded with triphenylsulfonium hexafluoroantimonate (13% w/w) in cyclohexanone. One micron thick films were spin coated on NaCl plates, baked at 140°C for 5 minutes to expel solvent and then subjected to infrared spectroscopic analysis before and after exposure. Exposure to 18 mJ/cm2 at 254 nm caused no change in the infrared spectrum. However, when the films were baked at 140°C for 120 sec. following exposure, deprotection was quantitative based on loss of the characteristic carbonate C = O absorption and... 

The various problems connected with the use of infrared spectroscopy in pesticide research have been reviewed by Frehse (1963). The paper dealt with qualitative and quantitative analysis, determinations of residues, and special problems such as methods of extraction, cells, solvents, and measuring attachments to be used. Frehse has given many references to the literature concerning the infrared spectroscopic analysis of various food crops for pesticides, e.g., aldrin, alodan, chlorbenside, DDT, dieldrin, endrin, ethion, lindane, malathion, tedion, endosulfan, biphenyl, captan, pentachloronitrobenzene, 2,4-DB, MCPB, and methylisothiocyanate. The infrared band(s) used for the determinations have also been given. 

A great deal of information about the location of oxygen in coal has been derived from infrared spectroscopic investigations. However, infrared spectroscopic data tend to suffer from their inability to be quantitative and can, at best, be used to illustrate trends throughout the progression from low-rank coals to high-rank coals (Table 10.11). 

Journal of Applied Polymer Science 62, No.ll, 12th Dec. 1996, p. 1903-11 SURFACE AND INTERFACIAL FOURIER TRANSFORM INFRARED SPECTROSCOPIC STUDIES OF LATEXES. XVI. QUANTITATIVE ANALYSIS OF SURFACTANT IN MULTILAYERED FILMS Niu B J Urban M W North Dakota State University... 

The improvement in computer technology associated with spectroscopy has led to the expansion of quantitative infrared spectroscopy. The application of statistical methods to the analysis of experimental data is known as chemometrics [5-9]. A detailed description of this subject is beyond the scope of this present text, although several multivariate data analytical methods which are used for the analysis of FTIR spectroscopic data will be outlined here, without detailing the mathematics associated with these methods. The most conunonly used analytical methods in infrared spectroscopy are classical least-squares (CLS), inverse least-squares (ILS), partial least-squares (PLS), and principal component regression (PCR). CLS (also known as K-matrix methods) and PLS (also known as P-matrix methods) are least-squares methods involving matrix operations. These methods can be limited when very complex mixtures are investigated and factor analysis methods, such as PLS and PCR, can be more useful. The factor analysis methods use functions to model the variance in a data set. 

A classic method is to digest the PHB-containing cell culture with sodium hypochlorite and measure the turbidity of the suspension produced by release of the polymer granules. Alternatively the polymer can be extracted into chloroform solution and its infrared absorbance at 1728 cm determined quantitatively. Another spectroscopic method involves hydrolysing and dehydrating the polymer to crotonic acid with concentrated sulphuric acid and assaying this by conventional quantitative UV analysis. ... 

With this rapid growth of near-infrared spectroscopic research in the health sciences, it is time for a text such as this. The authors have combined more than 35 years of industrial and university research experience in this volume. The pharmaceutical presentation is arranged in a logical progression theory, instrumentation, physical manipulation (blending, drying, and coating), analysis (both qualitative and quantitative), and finally, validation of the method. The varied mathematics used in NIR, called chemometrics, are only briefly mentioned. Detailed explanations and applications are covered in texts or chapters devoted to the subject [1-4]. 

An early compilation of established quantitative infrared polymer/additive methods was published [164] no update seems to be available. Various reviews on quantitative (surface) IR analysis have appeared [18,130,159,165,166,166a]. Several textbooks discuss basic considerations concerning quantitative analysis by vibrational spectroscopy [167-169]. Data processing techniques for quantitative analysis are covered by Koenig [170], in particular regarding theory and application of FTIR to the characterisation of polymers. Hummel [171] has also discussed quantitative IR spectroscopic analysis of additives. 

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