Near-infrared spectroscop spectroscopy

N. Broad, P. Graham, P. Hailey, et al., Guidelines for the development and validation of near-infrared spectroscopic methods in the pharmaceutical industry. In Handbook of Vibrational Spectroscopy, vol. 5, J.M. Chalmers and PR. Griffiths (eds), John Wiley Sons Ltd, Chichester, 3590-3610, 2002. 

Samples for analysis may be solids, liquids, or gases, or any forms in between and in combination, such as slurries, gels, and gas inclusions in solids. Samples can be clear or opaque, highly viscous or liquids with lots of suspended solids. While this variety is easy for Raman spectroscopy, it would be challenging for mid-IR and near-infrared (NIR) spectroscopy and numerous non-spectroscopic approaches. 

Vibrational Spectroscopy [Infrared (mid-IR, NIR), Raman]. In contrast to X-ray powder diffraction, which probes the orderly arrangement of molecules in the crystal lattice, vibration spectroscopy probes differences in the influence of the solid state on the molecular spectroscopy. As a result, there is often a severe overlap of the majority of the spectra for different forms of the pharmaceutical. Sometimes complete resolution of the vibrational modes of a particular functional group suffices to differentiate the solid-state form and allows direct quantification. In other instances, particularly with near-infrared (NIR) spectroscopy, the overlap of spectral features results in the need to rely on more sophisticated approaches for quantification. Of the spectroscopic methods which have been shown to be useful for quantitative analysis, vibrational (mid-IR absorption, Raman scattering, and NIR) spectroscopy is perhaps the most amenable to routine, on-line, off-line, and quality-control quantitation. 

G. E. Ritchie and E. W. Ciurczak, Validating a Near-Infrared Spectroscopic Method, Proc. Spectroscopy in Process and Quality Control Conference, New Brunswick, NJ, October, 1999. 

Ritchie, G. E. and Ciurczak, E. W. Validating a near-infrared spectroscopic method. In Spectroscopy in Process and Quality Control Conference Proceedings, East Brunswick NJ, 1999. 

Near-infrared (NIR) spectroscopy is becoming an important technique for pharmaceutical analysis. This spectroscopy is simple and easy because no sample preparation is required and samples are not destroyed. In the pharmaceutical industry, NIR spectroscopy has been used to determine several pharmaceutical properties, and a growing literature exists in this area. A variety of chemoinfometric and statistical techniques have been used to extract pharmaceutical information from raw spectroscopic data. Calibration models generated by multiple linear regression (MLR) analysis, principal component analysis, and partial least squares regression analysis have been used to evaluate various parameters. 

There are also more recent developments of other dual physio-chemical experimental methods. For example Durand et al (2006) presented a laboratory-made system that allows the coupling of dielectric analysis and Fourier-transform near-infrared spectroscopy (FT-NIR) to follow the cure of polyepoxy reactive systems. Complementary data are provided by the simultaneous dielectric analysis (the vitrification phenomenon) and near-infrared spectroscopic analysis (the extent of the reaction). 

Hall J W, McNeil B, Rollins M J, Draper I, Thompson B G, Macaloney G (1996). Near-infrared spectroscopic determination of acetate, ammonium, biomass and glycerol in an industrial Escherichia coli fermentation. Appl. Spectroscopy 50 102-108. 

Downey, G., McIntyre, R, and Davies, A.N. Geographic classification of extra virgin olive oils from the eastern Mediterranean by chemometric analysis of visible and near infrared spectroscopic data. Applied Spectroscopy, 57, 158-163. 2003. 

Among the optical analysis methods, near-infrared (NIR) spectroscopy is the most popular method because of its non-destructive nature, the low operating cost and the fast response times (Armenia et al., 2007), and it also has been successfully applied to quality control in food (Pi et al., 2009 Leroy et al., 2003 Subbiah et al., 2008), petrochemical, pharmaceutical, clinical and biomedical and environmental sectors (Ripoll et al., 2008). Near-infrared (0.7-2.5pm 12900-4000cm-i) spectroscopy is further classified into NIR reflectance spectroscopy and NIR transmission spectroscopy. NIR can be non-dispersive (filter-based instrumentation), dispersive and use Fourier transform-based instrumentation. Table 1 lists some NIR spectroscopic applications suitable for pesticides determination. All these researches have shown the possibility and reasonability for determination of pesticide concentration using NIR spectroscopy. 

Figure 7.20 Comparison of the NIR (spectroscopic) predicted serum analyte levels with reference analytical results (o) calibration set ( ) validation set [62]. Reprinted from Anal. Chim. Acta, 371, Hazen, K. H., Arnold, M. A. and Small, G. W., Measurement of glucose and other analytes in undiluted human serum with near-infrared transmission spectroscopy , 255-267, Copyright (1998), with permission from Elsevier.

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... 

J.W. Hail, A. Pollard Near-infrared spectroscopic determination of serum total proteins, albumin, globulins and urea. Clin. Biochem. 26, 483 (1993) Y. Mendelson, A.C. Clermont, R.A. Peura, B.-C. Lin Blood glucose measurement by multiple attenuated total reflection and infrared absorption spectroscopy. lEEB Tkans. Biomed. Eng. 37, 458 (1990)... 

Fourier transform near-infrared spectroscopy, using the C=CH band at 61S2cm for methacrylates, enabled the conversion to be followed in a single sample throughout the polymerization to high conversion. Parallel experiments were performed for near-infrared spectroscopic determination of monomer concentrations and for ESR measurements of radical concentrations. A further advantage of the near-IR method is its applicability to insoluble crosslinked systems. 

Chromatographic and spectroscopic techniques are within the most important tools used in food autherrtication. In particular, gas chromatography (GC) and liquid chromatography (LC) are widely used for the determination of both polar and non-polar compormds (volatile compormds in the case of GLC and organic acids, amino acids, polyphenols, etc., for LC). Almost aU the irrfrared spectroscopic techniques, near infrared (NIR) spectroscopy and mid-irtfrared (MIR) spectroscopy, are cheap, rapid, and non-destructive. AU of them are frequently used in combination with chemometrics. 

Near-infrared spectroscopy is quickly becoming a preferred technique for the quantitative identification of an active component within a formulated tablet. In addition, the same spectroscopic measurement can be used to determine water content since the combination band of water displays a fairly large absorption band in the near-IR. In one such study [41] the concentration of ceftazidime pentahydrate and water content in physical mixtures has been determined. Due to the ease of sample preparation, near-IR spectra were collected on 20 samples, and subsequent calibration curves were constructed for active ingredient and water content. An interesting aspect of this study was the determination that the calibration samples must be representative of the production process. When calibration curves were constructed from laboratory samples only, significant prediction errors were noted. When, however, calibration curves were constructed from laboratory and production samples, realistic prediction values were determined ( 5%). 

Miniaturized chemical analysis systems have been developed for most macroscopic counterparts (Dittrich et al. 2006). The availability of optical fibers, light sources, and detectors in the visible UV and near-infrared (NIR) wavelengths makes it possible to integrate spectroscopic measurements in microreactors (Lobbecke et al. 2005). Fourier transform infrared spectroscopy (FTIR) is an efficient, broadly applicable... 

The absorption spectroscopy has been widely used for monitoring the rate of chemical reactions. During the reaction, if there is either appearance of colour in a colourless solution or disappearance of colour in a coloured solution or a species which absorbed at a specific wavelength is formed, the spectroscopic technique can be used. Instruments like colorimeters and spectrophotometers are available to cover the visible, near infrared and ultra violet region of the spectrum (200-1000 nm). The absorption spectroscopy is governed by well-known Beer-Lambert s Law according to which ... 

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