Fourier transform infrared disadvantages

Chemical and instrumental (e.g., chromatography and mass spectrometry) methods have provided valuable information that lead to the advancement of cheese science. However, these techniques suffer from one or more of the following problems (1) the extensive use of solvents and gases that are expensive and hazardous, (2) high costs, (3) the requirement of specific accessories for different analytes, (4) the requirement of extensive sample preparation to obtain pure and clean samples, and (5) labor-intensive operation. These disadvantages have prompted for the evaluation and adoption of new, rapid, and simple methods such as Fourier-transform infrared (FTIR) spectroscopy. Many books are available on the basics of FTIR spectroscopy and its applications (Burns and Ciurczak, 2001 Sun, 2009). FTIR spectroscopy monitors the vibrations... 

Atomic absorption spectrometry (AAS), atomic emission spectrometry (AES) [11], infrared (IR), Fourier transform infrared (FTIR) and Raman spectroscopy have all been studied at various times for the determination of silicon compounds. AAS has been used to determine silicon in methylisobutylketone, chloroform or petroleum ether extracts of packaging materials and foodstuffs [12-17]. However, these methods suffer from the disadvantage that they do not distinguish between organic and inorganic silicon compounds, similarly inductively coupled plasma AES measures total silicon [11]. 

Starch and its blends have attracted much attention as environmentally biodegradable polymers (29-31). However they suffer fi-om disadvantages as compared with conventional polymers and blends such as brittleness and a narrow processability window (32). The thermal behavior and phase morphology of starch-blend systems have been studied by differential scanning calorimetry (DSC), Fourier Transform Infrared (FTIR) spectroscopy, scanning electron microscopy solvent extraction. X-ray diffraction, optical rotation, nuclear magnetic resonance (NMR) and polarizing optical microscopy (33-36). Like polymer blends wide applications starch-based blends have the potential to be... 

Although the artifact problem is annoying, the many advantages of FTIR make it the spectrometer of choice for analyzing most samples. Table 1.2 summarizes the advantages and disadvantages of Fourier Transform Infrared spectrometers. 

Fourier transform infrared (FTIR) vibrational spectroscopy senses the hydrogen bonding pattern of the peptide bonds of a protein and can detect unfolding transitions in terms of changes in the secondary stmcture patterns. As compared to CD, which also senses secondary stmcture, FTIR is relatively more responsive to jS-sheet stmc-tures. A disadvantage of FTIR is that it requires a higher protein concentration and that it is more difficult to automate for titration experiments. 

The diffuse reflectance method (DRIFTS - diffuse-reflectance infrared Fourier-transform spectroscopy) is a popular alternative sampling technique [31] that requires no specific sample preparation or only a dilution with a non-absorbing material (e.g. KBr or KCl). The main disadvantage of DRIFTS is the sensitivity to particle-size effects, which must be considered for quantitative assays. 

Fourier Transform-Near infrared (FT-NiR). Only within the last 20 years has FT-NIR instrumentation (Fig. 4.1.14) become available. Even then, the first commercial instmments had a distinct disadvantage compared to grating-based scanning instruments. FT-NIR spectrometers employ an entirely different method for producing spectra. There is no dispersion involved. Energy patterns set up by an interaction with a sample and a reference and moving mirrors (or other optical components) produce sample and reference interferograms that are used to calculate the absorbance spectrum of the sample. 

The advantages of Fourier transform spectrometry over the use of a scanning monochromator (often referred to as dispersive spectrometry) is fully valid only when the detector noise is independent of the power of the radiation incident on the detector. When the detector is photon shot-noise limited [as it generally is for a photomultiplier tube (PMT), and often is for other sensitive detectors used in the near-infrared, visible, and ultraviolet spectral regions], the noise level is proportional to the square root of the incident power. For a boxcar spectrum, this means that shot noise is proportional to the square root of the number of resolution elements in the spectrum, This disadvantage therefore precisely offsets Fellgett s advantage when continuous broadband sources are employed. It should also be... 

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