Attenuated total reflectance Fourier method

Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy. Attenuated total redectance (atr) ftir spectroscopy is based on the principle of total internal redection (40). Methods based on internal redection in the uv and visible regions of the spectmm are also common in addition to those in the ir region. The implementation of internal redection in the ir region of the spectmm provides a means of obtaining ir spectra of surfaces or interfaces, thus providing moleculady-specific vibrational information. 

This unit describes the attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopic method (AOCS, 1999a AOAC International, 2000), a novel method for measuring the total amount of fat with isolated trans double bonds. It is applicable to natural fats (ruminant fats) and processed fats and oils (partially hydrogenated fats and oils or refined vegetable oils) consisting of long-chain fatty acid methyl esters or triacylglycerols with trans levels >5%, as percent of total fat (AOAC International, 2000). 

Yang and Her [ 193] have described a rapid method for the determination of down to 200 ppt of semi-volatile compounds such as 1-chloronaphthalene, nitrobenzene and 2-chlorotoluene in soils by coupling solid-phase microextraction with attenuated total reflectance Fourier transform infrared spectroscopy. 

To shed light on the mechanism of formation of silsesquioxane a7b3, to identify the species formed during the process, and to try to explain the high selectivity towards structure a7b3 of the optimised synthetic method described above (64% yield in 18 h), the synthesis of cyclopentyl silsesquioxane a7b3 was monitored by electrospray ionisation mass spectrometry (ESI MS) [50-52] and in situ attenuated total reflection Fourier-transform infrared (ATR FTIR) spectroscopy [53, 54]. Spectroscopic data from the latter were analysed using chemometric methods to identify the pure component spectra and relative concentration profiles. 

Characterization. The PPNVP and PPNVP/PEUU films were characterized by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), electron spectroscopy for chemical analysis (ESCA), ellipsometry, and water contact angles in air. Two independent methods, a modification of the radioimmunoassay used by Ziats, et. al. (14) and an immunochemical stain based on the ABC immunohistochemical staining method (15) were developed to assay the binding of GOx to the PPNVP/PEUU support. 

Brancaleon, L., Bamberg, M.P., Sakamaki, T., and Kollias, N. Attenuated total reflection-Fourier transform infrared spectroscopy as a possible method to investigate biophysical parameters of stratum corneum in vivo. J. Invest Dermatol. 2001 116 380-386. 

The starch content in paper is determined by a TAPPI test method.301 Special methods are needed to assay starch in the presence of other adhesives.302 Starch on the paper surface is determined by ATR (attenuated total reflection) Fourier transform IR spectroscopy.303 New methods are being developed by the International Standards Organization (ISO).304... 

In this section we discuss a method of controlled material degradation for individual organic semiconductors and also for the blends used in bulk heterojunction solar cells [37]. The degradation is studied using attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and by determining current/voltage characteristics (I/V measurements) of the devices. 

Simple and rapid spectroscopic methods, such as front-face fluorescence, attenuated total reflectance Fourier-transform infrared and nuclear magnetic resonance spectroscopies, have a great potential for investigation of the structure of fats in dairy products and of the relation between structure and texture. Although fluorescence, infrared and NMR spectroscopies are techniques, the theory and methodology of which have been exploited extensively in studies in both chemistry and biochemistry, the usefulness of these spectroscopies for molecular studies has not been yet fully recognized in food science. Fluorescence, infrared and NMR spectroscopies coupled... 

A number of experimental alternatives to traditional IR transmission spectroscopy are suitable for overcoming some of these complicating experimental factors. In the technique of diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) (Hartauer et al. 1992 Neville et al. 1992) the sample is dispersed in a matrix of powdered alkali halide, a procedure which is less likely to lead to polymorphic transformations or loss of solvent than the more aggressive grinding necessary for mull preparation or pressure required to make a pellet (Roston et al. 1993). For these reasons, Threlfall (1995) suggests that DRIFTS should be the method of choice for the initial IR examination of polymorphs. He has also discussed the possible use of attenuated total reflection (ATR) methods in the examination of polymorphs and provided a comparison and discussion of the results obtained on sulphathiazole polymorphs from spectra run on KBr disks, Nujol mulls and ATR. 

Surface analytical techniques. A variety of spectroscopic methods have been used to characterize the nature of adsorbed species at the solid-water interface in natural and experimental systems (Brown et al, 1999). Surface spectroscopy techniques such as extended X-ray absorption fine structure spectroscopy (EXAFS) and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) have been used to characterize complexes of fission products, thorium, uranium, plutonium, and uranium sorbed onto silicates, goethite, clays, and microbes (Chisholm-Brause et al, 1992, 1994 Dent et al, 1992 Combes et al, 1992 Bargar et al, 2000 Brown and Sturchio, 2002). A recent overview of the theory and applications of synchrotron radiation to the analysis of the surfaces of soils, amorphous materials, rocks, and organic matter in low-temperature geochemistry and environmental science can be found in Fenter et al (2002). 

Increasing use is being made of Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy, FTIR-ATR, as a surface sensitive method which is capable of giving quantitative... 

ATR-FTIR spectroscopy (attenuated total reflectance Fourier transform infrared spectroscopy)—IR spectroscopy uses the absorption of infrared radiation to probe the vibrational frequency of molecular motions. Attenuated total reflectance method uses a crystal of high refractive index to channel the infrared light (using total internal reflectance) into the crystal and causes only a thin layer of a sample in contact with the exterior of the crystal to be sensitively detected. 

Spectroscopic methods are mainly useful to identify the elements, functional groups, and chemical structures close to the biomaterial surface. Techniques like X-ray photoelectron spectroscopy, attenuated total reflection fourier transform infrared spectroscopy, and secondary ion mass spectrometry have been used widely in determining the elemental composition and charged species at biomaterial surface. Other important characteristics obtained from the biomaterial surface are surface energy and relative wettability using thermodynamic method such as contact angle experiments. 

Attenuated total reflection-Fourier transform infra-red (ATR-FTIR) spectroscopy was used to determine the concentration of a chemical additive (cationic polyacrylamide resin) within a pulp fibre. The depth distribution of the additive was determined by sputter etching the fibre surface. The obtained profile was compared qualitatively with that obtained by the variable-angle ATR-FTIR depth profiling method. Most of the additive was located at the surface, with some distributed within the fibre. It is concluded that the method can be used to clarify the distribution of other paper additives within a pulp fibre, and that it can be applied to depth profiling of minor components within a solid material. 21 refs. 

The stmctural and conformational analysis of proteins adsorbed to solid surfaces is difficult because most common analytical methods are not compatible with the presence of the interacting solids. With recent developments in instrumentation and techniques, our understanding of protein adsorption behavior has improved considerably [4, 14]. The most commonly used techniques include attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), radiolabeling techniques, immunofluorescence enzyme-linked immunosorbent assay (ELISA), ellipsometry, circular dichroism (CD) spectroscopy, surface plasmon resonance (SPR), and amide HX with nuclear magnetic resonance (NMR). Atomic force microscopy (AFM) and scanning... 

Hanh BD, Neubert RHH, Wartewig S, Christ A, and Hentzsch C (2000) Drug penetration as studied by non-invasive methods Fourier transform infrared-attenuated total reflection, Fourier transform infrared, and ultraviolet photoacoustic spectroscopy. Journal of Pharmaceutical Sciences 89 1106-1113. 

To determine the surface chemical composihon, Fourier transform infrared (FT-IR) spectroscopy with an attenuated total reflection (ATR) method was performed (Nicolet Avator 230). The FT-IR spectrum of the powder sample was obtained with an FT-IR spectrometer (Bruker Tensor 27). 

Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) method can be used for spectral characterization of the physical properties of the synthetic mbber nanocompounds, as well as other complex samples such as polymer... 

ATR-FTIR Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy Infrared hght Detailed chemical information. Nonvacuum method. Specimens must be flat and capable of intimate contact with the necessary crystal. 

Among these, some of the most frequently used are attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. X-ray photoelectron spectroscopy (XPS), static secondary ion mass spectrometry (SSIMS), energy dispersive X-ray spectroscopy (EDS), optical microscopy, laser confocal scanning microscopy (LCSM), scanning electron microscopy (SEM), enviromnental scanning electron microscopy (ESEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), contact angle measurement, and some evaluation methods for the biocompatibility of membrane surfaces. 

These workers developed dynamic compression modulation attenuated total reflection Fourier transform infrared spectroscopic methods for characterising polymer films. To obtain dynamic compression polarised ATR spectra, internal reflection element (IRE) secure assemblies made of tungsten carbide with very high hardness were designed. 

The third method compared used modified attenuated total reflection Fourier transform infiared, ATR-FTIR. The specimen was part of a sandwich containing... 

The third method compared used modified attenuated total reflection Fourier transform infrared, ATR-FTTR. Specimen was part of a sandwich containing from bottom to top ATR crystal, specimen, aluminum foil, rubber heater, aluminum block with thermocouple, load cell, and aluminum block - all inserted into a press.This setup allows to control and measure the pressure applied to sample, and the temperature of the test. Result of testing comes in the form of reading of concentration by infrared in time intervals. The problems with the method are three migration occurs to the surface contacted with crystal (not with air or another layer of film as normally happens in practice), pressure must always be exerted to obtain proper readings (but pressure is known to change diffusion of additives), and accumulation of additive on surface of crystal may influence migration rate. 

An elegant alternative method to measure sorption into polymers is the Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) method. It allows in situ acquisition of the kinetic data and at the same time records the changes that occur in the polymer matrix due to the influence of the diffusant. Effects such as swelling, changes in morphology and polymer solvent interactions can all be simultaneously monitored. To calculate the diffusion coefficients from ATR-FTIR data, the mass uptake equation used in gravimetric diffusion experiments has to be modified to take into account the convolution of the evanescent field with the diffusion profile. 

Alia- testing, the following test methods were performed on the selected tested specimens Visual examination of the specimens was performed to identify the modes of failure. Oxidation induction time (OIT) was performed in general accordance with ISO 11357-6-2002 (E) [10] at 200 °C. Specimens wo-e taken liom the inner and outer surfaces as well as liom the bulk pipe wall and Micro-attenuated total reflection Fourier Transform Infrared Spectroscopy (micro-ATR) was performed. The inner surface and the fracture surface were examined. Scaiming Eleetron Microscopy (SEM) coupled with Energy Dispersive X-ray analysis (EDX) was performed on the iimer surface and the fiacture surface. 

A number of techniques have been employed that are capable of giving information about amorphous phases. These include infrared spectroscopy, especially the use of the attenuated total reflection (ATR) or Fourier transform (FT) techniques. They also include electron probe microanalysis, scanning electron microscopy, and nuclear magnetic resonance (NMR) spectroscopy. Nor are wet chemical methods to be neglected for they, too, form part of the armoury of methods that have been used to elucidate the chemistry and microstructure of these materials. 

The infrared technique has been described in numerous publications and recent reviews were published by Davies and Giangiacomo (2000), Ismail et al. (1997) and Wetzel (1998). Very few applications have been described for analysis of additives in food products. One interesting application is for controlling vitamin concentrations in vitamin premixes used for fortification of food products by attenuated total reflectance (ATR) accessory with Fourier transform infrared (FTIR) (Wojciechowski et al., 1998). Four vitamins were analysed - Bi (thiamin), B2 (riboflavin), B6 (vitamin B6 compounds) and Niacin (nicotinic acid) - in about 10 minutes. The partial least squares technique was used for calibration of the equipment. The precision of measurements was in the range 4-8%, similar to those obtained for the four vitamins by the reference HPLC method. 

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