Mid-infrared Fourier transform

Urbano Cuadrado, M. et al.. Comparison and joint use of near infrared spectroscopy and Fourier transform mid-infrared spectroscopy for the determination of wine parameters, Talanta, 66, 218, 2005. 

It is generally assumed the fluorescence and Fourier transform mid-infrared (FT-IR) spectroscopies do not suffer from the above-mentioned inconveniences and may be applied to turbid samples. Front-face (fluorescence) and attenuated total reflection (FT-IR) techniques may provide information on the structure of adsorbed proteins. 

Torano and Van Hattum [27] used Fourier transform mid-infrared (FTMIR) spectroscopy with an attenuated total reflection (RTR) module for determination of vigabatrin. The drug was extracted from the capsule content after addition of sodium thiosulfate IS solution. The extract was concentrated and applied to the FTMIR-ART module. The ratio of the area of the drug peak to that of the IS was linear over the concentration range of 90-110 mg/ml. The accuracy of the method in this range was 99.7-100.5% with a variability of 0.4-1.3%. 

Bhargava, R. and Levi, I. W. (2005) Fourier transform mid-infrared spectroscopic imaging. 

The Fourier transform mid-infrared (FTIR) spectra of the talc materials from the various vendors were measured by the neat, diffuse reflectance technique. Spectra of the three materials, acquired at a spectral resolution of 1 cm1, are presented in Figure 5. Identical spectra, including peak frequencies, peak width at half height, and peak shape, were measured for the three sources of talc. The major absorption bands and assignments are detailed in Table II [23]. 

Bhargava, R. and Levin, I.W. (2005) Fourier transform mid-infrared spectroscopic imaging, Ch. 1 in Spectrochemical Analysis Using Infrared Multichannel Detectors (eds R. Bhargava and I.W. Levin), Blackwell Publishing Ltd, Oxford, UK, pp. 1-24. 

Kos, G., Lohninger, H. and Krska, R. (2002) Fourier transform mid-infrared spectroscopy with attenuated total reflection (FT-IR/ATR) as a tool for the detection of Fusarium fungi on maize. Vih. Spectrosc., 29, 115-19. 

Fourier transform mid-infrared (FTIR), near-infrared (FTNIR), and Raman (FT-Raman) spectroscopy were used for discrimination among 10 different edible oils and fats, and for comparing the performance of these spectroscopic methods in edible oil/fat studies. The FTIR apparatus was equipped with a deuterated triglycine sulfate (DTGS) detector, while the same spectrometer was also used for FT-NIR and FT-Raman measurements with additional accessories and detectors. The spectral features of edible oils and fats were studied and the unsaturation bond (C=C) in IR and Raman spectra was identified and used for the discriminant analysis. Linear discriminant analysis (LDA) and canonical variate analysis (CVA) were used for the disaimination and classification of different edible oils and fats based on spectral data. FTIR spectroscopy measurements in conjunction with CVA yielded about 98% classification accuracy of oils and fats followed by FT-Raman (94%) and FTNIR (93%) methods however, the number of factors was much higher for the FT-Raman and FT-NIR methods. 

Quantification of microbial PHA using GC method is rapid, sensitive, reproducible, and requires only small amount of samples (5-10 mg) for the analysis. Other techniques of analysis such as IR spectrometry at 5.75 A (Juttner et al. 1975), two-dimensional fluorescence spectroscopy, flow cytometry (Degelau et al. 1995) HPLC (Karr et al. 1983), ionic chromatography, and enzymatic determination (Hesselmann et al. 1999) were also desalbed. For online determination of PHA content in recombinant E. coli system, Fourier transform mid-infrared spectrometry (FTIR) and microcalorimetric technique (Ruan et al. 2007 Jarute et al. 2004) were also reported. For precise composition determination and structural elucidation of PHA, a variety of nuclear magnetic resonance (NMR) spectroscopy techniques have also been applied and the most commonly used are proton ( H) and carbon-13 ( C) NMR (Doi et al. 1986 Jacob et al. 1986). 

R. H. Wrlson, B. J. Goodfellow, P. S. Belton, B. G. Osborne, G. Oliver, P. L. Russell. Comparison of Fourier Transform mid infrared reflectance spectroscopy with differential scanning calorimetry for the study of the staling of bread. J Sci FoodAgric 54 471-483, 1991. 

Olinga A, Winzen R, Rehage H, Siesler HW. Methyl methacrylate on-line polymerisation monitoring by hght-fibre Fourier transform near infrared transmission spectroscopy and Fourier transform mid infrared/attenuated total reflection spectroscopy. J Near Infrared Spectrosc 2001 9 19-24. 

FT-MIR, Fourier transform mid-infrared spectroscopy 2D-CoS, two-dimensional correlation spectroscopy 3D-FF fluorescence spectroscopy, 3D-font-face fluorescence spectroscopy ICA, independent component analysis SIA, sequential injection analysis EEM, excitation and emission matrices. V ... 

Finally, in the field of full-spectrum NIRS methods, Fourier transform near-infrared (FTIR) analyzers are included (Figure 5.5). FTIR techniques are predominant in mid-infrared spectroscopy because there are clear and absolute advantages for the FTIR analyzer in the mid-infrared compared with any other available technology. This arises because of the low power output of mid-infrared sources and the low specific detectivity... 

A mid-infrared absorption instrument generally consists of a Fourier transform design with the same basic components as noted above for the Fourier transform near-infrared spectrometers (broadband light source, Michelson interferometer, and detector optimized for the mid-infrared spectral region.)... 

Previous work of one of the authors dealt with mid IR monitoring of IB polymerization using fiber-optic equipment. Fourier transform near infrared spectroscopy can be accomplished without expensive hardware. It therefore seemed to be a desirable goal to combine the advantage of fiber optics with low-cost fibers available for measurements in the NIR range. The NIR spectrum of IB obtained after solvent subtraction (Figure 2) reveals at least three signals, which should be suitable for the determination of monomer conversion. 

Fourier Transform Mid-IR Test Apparatus—The type of apparatus suitable for use in this test method employs an IR source, an infrared transmission cell or a liquid attenuated total internal reflection cell, a scanning interferometer, a detector, an A-D converter, a microprocessor and a sample introduction system. 

Kidder L H, Levin I W, Lewis E N, Kleiman V D and Heilweil E J 1997 Mercury cadmium telluride focal-plane array detection for mid-infrared Fourier-transform spectroscopic imaging Opt. Lett. 22 742-4... 

For radiofrequency and microwave radiation there are detectors which can respond sufficiently quickly to the low frequencies (<100 GHz) involved and record the time domain specttum directly. For infrared, visible and ultraviolet radiation the frequencies involved are so high (>600 GHz) that this is no longer possible. Instead, an interferometer is used and the specttum is recorded in the length domain rather than the frequency domain. Because the technique has been used mostly in the far-, mid- and near-infrared regions of the spectmm the instmment used is usually called a Fourier transform infrared (FTIR) spectrometer although it can be modified to operate in the visible and ultraviolet regions. 

Principles and Characteristics Both mid-IR (2.5-50 p.m) and near-IR (0.8-2.5 p.m) may be used in combination to TLC, but both with lower sensitivity than UV/VIS measurements. The infrared region of the spectrum was largely ignored when the only spectrometers available were the dispersive types. Fourier-transform instruments have changed all that. Combination of TLC and FTIR is commonly approached in two modes ... 

While most of the references tend nowadays to use FT-IR/FTIR (Fourier transform infrared) to denote the use of mid-infrared spectroscopy we mostly use the more precise phrasing of mid-infrared (mid-IR) spectroscopy. 

In the mid-IR, routine infrared spectroscopy nowadays almost exclusively uses Fourier-transform (FT) spectrometers. This principle is a standard method in modem analytical chemistry45. Although some efforts have been made to design ultra-compact FT-IR spectrometers for use under real-world conditions, standard systems are still too bulky for many applications. A new approach is the use of micro-fabrication techniques. As an example for this technology, a miniature single-pass Fourier transform spectrometer integrated on a 10 x 5 cm optical bench has been demonstrated to be feasible. Based upon a classical Michelson interferometer design, all... 

The pharmaceutical industry comprises the largest segment, roughly 15 to 20%, of the infrared (IR) market. Modern mid-infrared instrumentation consists almost exclusively of Fourier transform (FT) instruments. Because of its ability to identify molecular species, FT-IR is routinely used as an identification assay for raw materials, intermediates, drug substances, and excipients. However, the traditional IR sample preparation techniques such as alkali halide disks, mulls, and thin films, are time-consuming and not always adequate for quantitative analysis. 

J.D. Tate, P. Chauvel, R. D. Guenard and R. Harner, Process monitoring by mid- and near-infrared Fourier transform spectroscopy, in Handbook of Vibrational Spectroscopy, volume 4, J.M. Chalmers, and P.R. Griffiths, (eds), John Wiley Sons Ltd, New York, 2002, pp. 2738-2750. 

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