Thermal analysis with Fourier transform infrared spectrometry

Understanding the relationship between the molecular structure and the thermal stability (decomposition temperature and rate) of the organoclays and the subsequent influence on the stability of the polymer host is critical. Several analytical techniques have been used to determine the thermal stability of different organoclays and to indentify the decomposition products conventional and high-resolution thennogravimetric analysis (TGA) coupled with Fourier transform infrared spectroscopy (FITR) and mass spectrometry (MS), pyrolysis/gas chromatography (GC)-MS, and solid phase microextraction (SPME) [6-12]. 

Reports on the detailed thermal behaviour of PEEK/HAp composites [as well as other polymer/HAp (nano)composites] are scarce in the literature. Advanced thermal analysis methods, e.g., modulated temperature differential scanning calorimetry (MTDSC) or hyphenated thermoanalytical methods such as thermogravimetry coupled with Fourier transform infrared spectroscopy (TG-FTIR) or mass spectrometry... 

Spectrometric methods, especially mass sf>ectrometry (MS) and Fourier transform infrared spectrometry (FilR) have been used, often coupled with thermogravimetry. For molecules that are pwlar and of low molar mass, FTIR is particularly useful. For nonpwlar molecules and those of higher molar mass, MS is more adaptable. There are problems, however, in interfacing the thermal analysis instrument operating at atmospheric pressure to the MS operating imder vacuum. This is discussed in Topic F3. 

An integrated GC/IR/MS instrument is a powerful tool for rapid identification of thermally generated aroma compounds. Fourier transform infrared spectroscopy (GC/IR) provides a complementary technique to mass spectrometry (MS) for the characterization of volatile flavor components in complex mixtures. Recent improvements in GC/IR instruments have made it possible to construct an integrated GC/IR/HS system in which the sensitivity of the two spectroscopic detectors is roughly equal. The combined system offers direct correlation of IR and MS chromatograms, functional group analysis, substantial time savings, and the potential for an expert systems approach to identification of flavor components. Performance of the technique is illustrated with applications to the analysis of volatile flavor components in charbroiled chicken. 

The spent catalysts were characterized by chemical analysis (carbon content), temperature programmed oxidation coupled to a mass spectrometer (TPO/MS) and thermal analysis (DTA and TG). The samples were also submitted to extraction of soluble coke in a soxhiet apparatus with n-hexane and dichloromethane for 24h, after being treated with fluoridric acid (40%) at room temperature (2h), followed by reflux with hydrocloric acid (36%) for 2h. The extracts were analyzed by gas-chromatography-mass spectrometry (GC/MS), Fourier transformer infrared spectroscopy (FTIR), ultraviolet spectroscopy (UV) and X ray diffraction. The insoluble fraction was analyzed by X ray diffraction and FTIR. 

There are a number of techniques that can be used in the field. These include electrochemical sensors for gases such as O2 and SO2 and diffusive samplers containing immobilized reagents that produce a visible color change with visual detection on exposure to a specific chemical. Passive diffusion tubes can also be used for analyte preconcentration. Subsequent laboratory analysis is usually undertaken by thermal desorption coupled with GC. This approach is particularly useful for trace organic compounds such as polyaromatic hydrocarbons (PAHs) and VOCs. Spec-trometric techniques such as Fourier transform infrared (FTIR) spectrometry, correlation spectrometry, and the laser based LIDAR (light detection... 

The use of infrared spectrometry for quantitive analysis became possible only in the 1980s, when affordable and user-friendly benchtop Fourier-transform spectrometers became available. The sensitivity of the FT-IR spectroscopy was, however, insufficient to meet the requirements of the immunoassay. To address this problem, an instrument equipped with a liquid nitrogen-cooled detector made from a semi-conducting material, for example MCT (mercury-cadmium-telluride) or InSb (indium antimonide), was used to increase sensitivity by a factor of 20 compared with the thermal detector DTGS found in standard FT-IR machines. Use of a light-pipe cell with a long optical path (20 mm) for a... 

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