Quantitative reflection spectroscopy

A.D. Patel, P.E. Luner and M.S. Kemper, Quantitative analysis of polymorphs in binary and multi-component powder mixtures by near-infrared reflectance spectroscopy, Int. J. Pharm. 206, 63-74. Erratum in Int. J. Pharm., 212, 295 (2000). 

Reeves, J.B. Ill and McCarty, G.W. (2001) Quantitative analysis of agricultural soils using near infrared reflectance spectroscopy and a fibre-optic probe. Journal of Near Infrared Spectroscopy 9, 25-34. 

Huck, C. et al., Quantitative Fourier transform near infrared reflectance spectroscopy (NIRS) compared to high performance liquid chromatography (HPLC) of a flavone in Primulae veris Flos extracts, Pharm. Pharmacol Lett., 9, 26, 1999. 

P Nishiyama, M Alvarez, LGE Vieira. Quantitative analysis of stevioside in the leaves of Stevia re-baudiana by near infrared reflectance spectroscopy. J Sci Food Agric 59(3) 277-281, 1992. 

The separation of transition-metal complexes of pyridine-2-carbaldehyde 2-quinolylhydrazone (PAQH) has been accomplished by TLC [63]. The method consists of separation of the metals as their PAQH chelates and quantitation in situ by reflectance spectroscopy. 

Pudelko-Koerner, C., Fischer, A., Lentzen, H., Glombitza, K.W. and Madaus, A.G. (1996) Quantitative Fourier transform-near infrared reflectance spectroscopy of sennosides in Senna pods Pharm. Pharmacol. Lett. 6, 34-36. 

Pudelko-Koerner, C. (1998) Quantitative near-infrared reflectance spectroscopy of sennosides from Sennae fructus angustifoliae in in-process and quality control including method validation Pharmazeutische Industrie 60, 1007-1012. 

O. Bemtsson, L.G. Danielsson, B. Lagerholm, S. Folestad, Quantitative in-line monitoring of powder blending by near infrared reflection spectroscopy, Powder Technol. 123 (2002) 185—193. 

Reeves, J. B., Ill, McCarty, G. W., and Reeves, V. B. (2001). Mid-infrared diffuse reflectance spectroscopy for the quantitative analysis of agricultural soils. J. Agric. Food Chem. 49, 766-772. 

ATR or diffuse reflection techniques are widely used for materials which are difficult to analyze by absorption methods, such as thin layers on nontransparent substrates, substances with very high absorption which are difficult to prepare in thin layers, or substances with a special consistency. Some basic considerations concerning quantitative ATR spectroscopy have been described by Muller et al. (1981). This publication emphasizes the fact that the functional behavior of the ATR spectrum of an absorbing sample must be evaluated with regard to the refractive index as well as to the absorption index of the sample. It is shown that, as a consequence, reflection measurements can be used to determine concentrations of nonabsorbing samples. Further information on reflection spectroscopy is presented in Sec. 6.4. 

Diffuse-reflection spectroscopy is a widely used experimental technique which, different from the previously mentioned techniques, is not only based on reflection and refraction but additionally on diffraction. The exact description, e.g. assuming Mie scattering, and quantitative simulation of the spectra is at least difficult (Grosse, 1990). The most comprehensive overview on all related aspects was given by Kortiim (1969). Experimental examples refer mostly to the visible spectral range, more recent reviews deal with near infrared (Osborne and Feam, 1986), infrared (Korte, 1990b), and far infrared spectroscopy (Ferraro and Rein, 1985). 

Weckhuysen, B.M., De Ridder, L.M. and Schoonheydt, R.A. (1993) A quantitative diffuse reflectance spectroscopy study of supported chromium catalysts. Journal of Physical Chemistry, 97 (18), 4755-53. 

In situ infrared reflectance spectroscopy investigation of the oxidation reaction of ethanol appears thus as an efficient method to elucidate some mechanistic aspects of the reaction. However, the quantitative analysis of the reaction products remains difficult due to different parameters the characteristic absorption band may not be monopolar (this is the case for carbon monoxide for example) and the difficulty to obtain a quantitative relationship between infrared extinction coefficients and concentration for reaction products and by-products. 

Blanco, M. Coello, J. Iturriaga, H. Maspoch, S. de la Pezuela, C. Quantitation of the active compound and major excipients in a pharmaceutical formulation by near infrared diffuse reflectance spectroscopy with fiber optical probe. Anal. Chim. Acta 1996, 333, 147-156. 

Greyson, J. and Zipp, A. (1978). The application of reflectance spectroscopy to quantitative analysis in clinical chemistry. Abstracts of Xth. Int. Congr. Clin. Chem., Mexico, p. 47, Abstr. 

Zipp, A., Watson, C. and Greyson, J. (1978). Reflectance spectroscopy as an analytical tool in the clinical laboratory Application to the quantitative determination of lactate dehydrogenase in serum. Clin. Chem. 24, 1009, Abstr. 105. 

Test strips were prepared by oxidation of cellulose with KIO4 to a polyaldehyde, followed by condensation with 1-naphthylamine to a poly-Schiff base and reduction with NaBH4 to an immobilized naphthylamine cellulose derivative, which is mechanically stabilized on a polypropylene sheet. PAA can be detected on addition of nitrite to the test solution and contacting with the strip, where azo dyes are formed. Quantitative analysis can be carried out by diffuse reflectance spectroscopy. The method was applied to pharmaceutical preparations with RSD better than 30%246. 

C. Pudelko-Korner, Quantitative Near-Infrared-Reflection-Spectroscopy of Sennosides in Sennae fructus angustifoliae in Processing and Quality Control as well as Validation of these Methods, Pharma Technol. J., 19(1), 57-67 (1998). 

Ghosh S and Cannon M D, Quantitative analysis of durable press resin on cotton fabrics using near-infrared reflectance spectroscopy , Textile Research Journal, 1990,60,167-172. 

Most attention has been paid to applications of absorption and reflection spectroscopy in the NIR region for industrial process control (Dallin, 1997, Kammona et al, 1999, Fernando and Degamber, 2006). This arises firom the robust nature of the optical components and the availability of commercial systems that are based on gratings as well as interferometers. Transmission and reflectance probes that are designed to interface with extruders, and in particular reactive extruders, are commercially available, and their performance has been assessed quantitatively (Hansen and BQiettry, 1994). The interface for a rugged NIR probe to monitor the molten flow of an extruder is shown in Figure 3.44. 

JB Reeves HI. Near- versus Mid-Infrared Diffuse Reflectance Spectroscopy for the Quantitative Determination of the Composition of Forages and By-products. Near Infrared Spectrosc. 2 49-57, 1994. 

Nagarajan, R., Gupta, A., Mehrotra, R. and Bajaj, M.M. (2006) Quantitative analysis of alcohol, sugar, and tartaric acid in alcoholic beverages using attenuated total reflectance spectroscopy. J Aut Meth Manag Chem, 2006 (2), 1-5. 

Taylor (1961) fonnd a maximum of one-third mole percent A1 substitution for Fe within goethite and a maximum of one-sixth substitution was determined for hematite in soils (Schwertmaim et al. 1979). As a product of terrestrial weathering magnetites usually contain minor amounts of Ti(IV) (ionic radius 0.69 A) as a substitution for Fe which is then called titano-magnetite. In contrast, bio-mineralized magnetite is a pure iron oxide. Different colors of iron oxides / oxyhy-droxide are immediately apparent in nature. This holds true for different pure iron oxides, for different grain sizes of one oxide (e.g. goethite) as well as for distinct substitutions for Fe, e.g. by Mn or Cr (Schwertmann and Cornell 1991). The color of synthetic minerals and natural sediment can be quantitatively determined by reflectance spectroscopy (e.g. Morris et al. 1985). 

In contrast to the well-known difficulties of traditionally applied quantitative IR spectroscopy of mixtures in solid (powdered) samples, the near-infrared reflectance analysis (NIRA) technique [32] has gained importance over the last decade and can now be implemented on a variety of commercially available Instruments In a number of applications to Industrial, agricultural and pharmaceutical analyses. Both the NIRA instruments equipped with grating monochromators and those fitted with filter systems feature built—In microprocessors with software suited to the Intrinsic characteristics of this spectroscopic alternative. Filter Instruments generate raw optical data for only a few wave-... 

The raw data that one obtains in reflection spectroscopy consist of the relative intensity of the reflected light as a function of the wavelength, and the first problem facing the experimentalist is converting these data in a quantitative fashion to the corresponding transmission spectra. Fortunately, a recent treatment by Melamed (16) permits one to calculate the extinction coefficient directly from reflectivity data if one knows the dielectric constant of the solid, and its particle size. Since these latter two quantities are readily obtained one can, in practice, rather easily determine the optical spectrum of an opaque powdered solid. 

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