Gas chromatography-FTIR

Reactivity measurements are in most cases possible with standard techniques (mass spectrometry, gas chromatography, FTIR, or other specific detectors), which are available today. New preparation methods will probably... 

Figure 5.10 Scheme for characterization of cyclic fatty acid monomers (CFAMs) from heated vegetable oils. HPLC = high-pressure liquid chromatography GC = gas chromatography FTIR = Fourier transform infra-red (spectroscopy) MS = mass spectrometry DMOX = dismethyloxazoline. 

Plasticized polyvinyl chloride Aqueous and food oils Di-2-n ethyl hexyl phthalate plasticizer, organotin heat stabilizer, processing aids, external and internal lubricants Gas chromatography FTIR spectroscopy, atomic absorption spectrometry, differential scanning calorimetry [172]... 

Gas chromatography-Fourier transform infrared spectroscopy (gc-ftir)... 

Analytical investigations may be undertaken to identify the presence of an ABS polymer, characterize the polymer, or identify nonpolymeric ingredients. Fourier transform infrared (ftir) spectroscopy is the method of choice to identify the presence of an ABS polymer and determine the acrylonitrile—butadiene—styrene ratio of the composite polymer (89,90). Confirmation of the presence of mbber domains is achieved by electron microscopy. Comparison with available physical property data serves to increase confidence in the identification or indicate the presence of unexpected stmctural features. Identification of ABS via pyrolysis gas chromatography (91) and dsc ((92) has also been reported. 

A review pubHshed ia 1984 (79) discusses some of the methods employed for the determination of phenytoia ia biological fluids, including thermal methods, spectrophotometry, luminescence techniques, polarography, immunoassay, and chromatographic methods. More recent and sophisticated approaches iaclude positive and negative ion mass spectrometry (80), combiaed gas chromatography—mass spectrometry (81), and ftir immunoassay (82). 

The crystalline mineral silicates have been well characterized and their diversity of stmcture thoroughly presented (2). The stmctures of siHcate glasses and solutions can be investigated through potentiometric and dye adsorption studies, chemical derivatization and gas chromatography, and laser Raman, infrared (ftir), and Si Fourier transform nuclear magnetic resonance ( Si ft-nmr) spectroscopy. References 3—6 contain reviews of the general chemical and physical properties of siHcate materials. 

Mixtures can be identified with the help of computer software that subtracts the spectra of pure compounds from that of the sample. For complex mixtures, fractionation may be needed as part of the analysis. Commercial instmments are available that combine ftir, as a detector, with a separation technique such as gas chromatography (gc), high performance Hquid chromatography (hplc), or supercritical fluid chromatography (96,97). Instmments such as gc/ftir are often termed hyphenated instmments (98). Pyrolyzer (99) and thermogravimetric analysis (tga) instmmentation can also be combined with ftir for monitoring pyrolysis and oxidation processes (100) (see Analytical methods, hyphenated instruments). 

The high degree of sensitivity, selectivity, and efficiency of gas chromatography allows the elucidation of a complete profile of the volatile components of distilled spirits. The wide selection of chromatographic columns and techniques, such as gc-ms, gc-ftir, and gc-ms-ftir, has allowed the chemist to routinely identify and quantify individual constituents on a parts-per-biUion level. The two most critical variables in the analysis of volatile components of distilled spirits by gas chromatography are the selection of a suitable chromatographic column and of the most appropriate detector. 

Identification of stmctures of toxic chemicals in environmental samples requires to use modern analytical methods, such as gas chromatography (GC) with element selective detectors (NPD, FPD, AED), capillary electrophoresis (CE) for screening purposes, gas chromatography/mass-spectrometry (GC/MS), gas chromatography / Fourier transform infra red spectrometry (GC/FTIR), nucleai magnetic resonance (NMR), etc. 

W. Herres, "HRGC-FTIR Capillary Gas Chromatography-Fourier Transform Infrared Spectrometry. Theory and Applications", Huethlg, Heidelberg, 1987. 

Gas chromatography (GC) and with mass spectrometry (GC-MS) Fourier transform infrared spectroscopy (FTIR)... 

If additional information pertaining to the rubber composition were sought, FTIR analysis of the pyrolysis products would have been performed. Even more detailed analysis can be obtained by gas chromatography (GC) separation of the multiple pyrolysis products followed by mass spectrometric (MS) detection. The gas chromatography-mass spectrometry (GC-MS) method is well suited to deformulation and contaminant analysis. 

The FTIR spectra of the gas mixture evolved in thermal decomposition of Bisphenol AF poly(formal) (7) at various temperatures suggest the existence of benzene rings, C—O—C bonds, and C=C bonds. In a pyrogram of pyrolysis gas chromatography (Py-GC) of Bisphenol A (3), a-methylstyrene, phenol, p-cresol, 4-hydroxy-amethylstyrene, and isopropyl phenol are observed as major peak products. The cleavage reactions shown in Scheme (5) is suggested for the formation of phenol and 4-hydroxy-a-methylstyrene from Bisphenol A (3). 

Due to its relatively low sensitivity, the combination of gas chromatography with Fourier transform infrared spectroscopy (GC-FTIR) is not a standard technique in semiochemical research. Nevertheless, it could come in handy for the identification of some compounds with utterly uninformative mass spectra [22]. 

Other methods for the determination of aromatics in naphtha include a method (ASTM D5580) using a flame ionization detector and methods that use combinations of gas chromatography and Fourier transform infrared spectroscopy (GC-FTIR) (ASTM D5986) and gas chromatography and mass spectrometry (GC-MS) (ASTM D5769). 

---