Near-infrared spectroscopy physical properties

Hanlon and Klotz (1968) have discussed the use of near-infrared spectroscopy for studying structural problems of biochemistry. In particular, they have considered the equilibrium state of the peptide unit in a number of synthetic polyamino acids (poly-L-alanine, poly-L-leucine, poly-L-methionine, and poly-y-benzyl-L-glutamate) as a function of solvent composition under conditions where the transitions in other physical properties of these polymers have been interpreted as simple peptide, hydrogen-bonded, helix-to-coil transitions. Their spectral data demonstrate that these conversions involve protonated peptide species and are far more complicated than investigators of these processes had assumed. 

Dziki et al. (93) used near-infrared spectroscopy to characterize the mobility of water within the sarafloxacin crystal lattice differences in the location or orientation of the water molecules within the crystal were detected. The presence or absence of water in the crystal lattice can affect physical properties and processing ability. Analysis of near-infrared spectra of polymer samples allows us to distinguish between acceptable and unacceptable batches for formulation purposes. 

Near-infrared spectroscopy (NIRS) can be used for product identification, classification and quality control, as well as for the determination of product properties (chemical and physical) and component concentrations in process applications, all with the object of rapid analysis. Near-IR analysis was born of a need to solve practical quality control problems rather than the desire to perform high-resolution molecular structure analysis in the laboratory. The samples subjected to NIRS are often very complex mixtures and are studied without any sample preparation. Competitor analysis is not possible. 

Volumes 50 and 51 of the Advances, published in 2006 and 2007, respectively, were the first of a set of three focused on the physical characterization of solid catalysts in the functioning state. This volume completes the set. The six chapters presented here are largely focused on the determination of structures and electronic properties of components and surfaces of solid catalysts. The first chapter is devoted to photoluminescense spectroscopy it is followed by chapters on Raman spectroscopy ultraviolet-visible-near infrared (UV-vis-NIR) spectroscopy X-ray photoelectron spectroscopy X-ray diffraction and X-ray absorption spectroscopy. 

Applied Spectroscopy 53, No.5, May 1999, p.557-64 COMPARISON OF NEAR-INFRARED AND RAMAN SPECTROSCOPY FOR THE DETERMINATION OF CHEMICAL AND PHYSICAL PROPERTIES OF NAPHTHA Min-Sik Ku Hoeil Chung SK Corp. 

Quantitative infrared spectroscopy can provide certain advantages over other analytical techniques. This approach may be used for the analysis of one component of a mixture, especially when the compounds in the mixture are alike chemically or have very similar physical properties (for example, structural isomers). In these instances, analysis using ultraviolet/visible spectroscopy, for instance, is difficult because the spectra of the components will be nearly identical. Chromatographic analysis may be of limited use because separation, of say isomers, is difficult to achieve. The infrared spectra of isomers are usually quite different in the fingerprint region. Another advantage of the infrared technique is that it can be non-destructive and requires a relatively small amount of sample. 

Near-infrared (NIR) spectroscopy has taken its place among other proven spectroscopic tools, especially for determining chemical and physical properties of foods and food products. Covering the small region of the electromagnetic spectrum from 780 to 2500 (nm) (Sheppard, 1985 354), producing spectra with only 860 data points spaced 2 nm apart, NIR spectroscopy has experienced phenomenal growth over its short history from 1905 (the year Coblentz produced the first official NIR publication) to the... 

Near-infrared (NIR) spectroscopy has been found to be a useful technique to characterize raw materials and finished textile products, and NIR methods and techniques continue to find increasingly diverse and wide-ranging quantitative and qualitative applications in the textile industry. Quantitative analyses determine the amount (or quantity) of the property/species of interest in a substance or material. Qualitative analyses can be used to either identify a specific species or subsfance present in a material (i.e., coating on a fiber), the type of material itself (i.e., cotton, nylon, or polyester), or the quality of the material. NIR quantitative and qualitative methods allow the user to rapidly, accurately, and precisely monitor key chemical, physical, and morphological properties of textile fibers, yarns, fabrics, and chemical textile auxiliaries. Chemical properties are specific chemical species or groups present in the material (i.e., CH, OH, NH) that result in NIR spectral absorbencies at distinctive... 

Spectroscopic techniques are powerful process analytical tools. They are unparalleled in terms of molecular specificity, minimal sample preparation that translates to speed, and are capable of inferring physical properties [63,67,68]. Mid-infrared Fourier transform spectroscopy (FTIR), near-IR (NIR), and Raman spectroscopic techniques are the workhorse tools commonly used to monitor online polymerization processes. 

NMR and infrared (IR) spectroscopy are also used to investigate the chemical stability of drug substances. Determination of the hydrolysis rate of esters such as atropine by NMR,647 a nondestructive near-IR analysis of aspirin tablets,648 and determination of the hydrolysis rate of diltiazem by polarimetry649 have been reported. Unusual methods, such as measurement of the dielectric properties of dosage forms like gelatin and methylcellulose microcapsules (Fig. 160), have been used to detect physical changes.650-651 These changes... 

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