Infrared spectrometry dispersive

The unique appearance of an infrared spectrum has resulted in the extensive use of infrared spectrometry to characterize such materials as natural products, polymers, detergents, lubricants, fats and resins. It is of particular value to the petroleum and polymer industries, to drug manufacturers and to producers of organic chemicals. Quantitative applications include the quality control of additives in fuel and lubricant blends and to assess the extent of chemical changes in various products due to ageing and use. Non-dispersive infrared analysers are used to monitor gas streams in industrial processes and atmospheric pollution. The instruments are generally portable and robust, consisting only of a radiation source, reference and sample cells and a detector filled with the gas which is to be monitored. 

Infrared spectrometry Rotatory dispersion early 1950 s 1955 Commercial instrument... 

Now, in order to employ a locked-in detection system, as in EMIRS, the modulation frequency of the potential at the electrode would have to be at least an order of magnitude greater than F(i). Thus, the potential modulation would have to be between 70 and 100 KHz, too great to allow sufficient relaxation time for most electrochemical processes to respond. As a consequence, lock-in detection has not been employed in in-situ FTIR studies and the sensitivity of SNIFTIRS is less than that of EMIRS. Nevertheless, the FT method does have the sensitivity necessary to detect monolayers, and submonolayers, of adsorbed species [55, 56]. This arises out of the very large improvements in S/N ratio available to FT (compared with dispersive) infrared spectrometry by the Jacquinot and Fellgett advantages. 

Table 5.2 Summary of selected analytical methods for molecular environmental geochemistry. AAS Atomic absorption spectroscopy AFM Atomic force microscopy (also known as SFM) CT Computerized tomography EDS Energy dispersive spectrometry. EELS Electron energy loss spectroscopy EM Electron microscopy EPR Electron paramagnetic resonance (also known as ESR) ESR Electron spin resonance (also known as EPR) EXAFS Extended X-ray absorption fine structure FUR Fourier transform infrared FIR-TEM Fligh-resolution transmission electron microscopy ICP-AES Inductively-coupled plasma atomic emission spectrometry ICP-MS Inductively-coupled plasma mass spectrometry. Reproduced by permission of American Geophysical Union. O Day PA (1999) Molecular environmental geochemistry. Rev Geophysics 37 249-274. Copyright 1999 American Geophysical Union...

NMR ( H, 13C), mass spectrometry, infrared (IR), and ultraviolet (UV) were used, especially NMR, in studying the complexation interactions of artemisinins with agents, such as /3-cyclodextrin <2004JPS2076> and micellar dispersions of octanoyl-6-O-ascorbic acid <2002JPS2265>. Furthermore, the structure-activity relationship of solution structures of deoxoartemisinin 10a and carboxypropyldeoxoartemisinin 10b, as antitumor compounds, was studied by H and 13C NMR <2000BBR359>. 

Infrared spectroscopy (IR) is one of the oldest instrumental analytical techniques but its value in structural analysis has decreased with the rise of nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS). Compared to the traditional dispersive IR techniques, Fourier transform infrared spectroscopy (FTIR) offers more sampling techniques. 

Newton MA, Dent AJ, Fiddy SG, Jyoti B, Evans J. Combining diffuse reflectance infrared spectroscopy (DRIFTS), dispersive EXAFS, and mass spectrometry with high time resolution potential, limitations, and application to the study of NO interaction with supported Rh catalysts. Catal Today. 2007 126 64. 

The elucidation and confirmation of structure should include physical and chemical information derived from applicable analyses, such as (a) elemental analysis (b) functional group analysis using spectroscopic methods (i.e., mass spectrometry, nuclear magnetic resonance) (c) molecular weight determinations (d) degradation studies (e) complex formation determinations (f) chromatographic studies methods using HPLC, GC, TLC, GLC (h) infrared spectroscopy (j) ultraviolet spectroscopy (k) stereochemistry and (1) others, such as optical rotatory dispersion (ORD) or X-ray diffraction. 

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