Spectroscopy transmittance

The use of electrochemical transmittance spectroscopy in both the UV-visible and IR regions of the spectrum is elegantly shown by the work of Ranjith et al. (1990) who employed an OTTLE cell to study the reduction of benzoquinone, BQ. The authors were the first to report the UV-visible spectrum of BQ2- and to demonstrate the quantitative aspects of the technique by reporting extinction coefficients for the major bands of BQT and BQ2- in both the UV-visible and IR. 

Russell, F., and Ulmschneider, M. (2004), Dissolution testing by means of NIR transmittance spectroscopy, Am. Pharm. Rev., July/August. 

Eutaquio, A. Blanco, M. Jee, R.D. etal., Determination of paracetamol in intact tablets by use of near infrared transmittance spectroscopy Anal. Chim. Acta 1999, 383, 283-290. 

Eustaquio A, Graham P, Jee RD, Moffatt AC, Trafford AD. 1998. Quantification of paracetamol in intact tablets using near-infrared transmittance spectroscopy. Analyst 123 2303-2306. 

Infrared spectra may be obtained for gases, liquids, orsolids. For transmittance infrared spectroscopy, the sampling techniques may involve a solution, a film, amull, or a pellet, depending on the type of sample. Reflectance spectroscopy differs from transmittance spectroscopy in that infrared radiation reflected from the surface of a material is studied. With a proper sampling accessory (obtainable from commercial sources), the materials analyzed by reflectance techniques normally require little or no sample preparation. The method is non-destructive, non-invasive, and very useful for analyzing materials that are too thick or have too much absorbance to be analyzed by transmittance spectroscopy. 

Obtaining the spectrum by transmittance spectroscopy normally requires sample cells with window materials that must be ... 

A problem that may be encountered when analyzing a solid sample by transmittance spectroscopy is radiation scattering. Employing reflectance spectroscopy can sometimes reduce this problem. With this technique, the infrared spectra of most solid materials are easily obtained with little or no sample preparation. Spectra of a wide range of solid samples can be characterized with this technique, such as coatings on beverage containers and silicon wafers, polymer films, or other intractable samples. The reflectance technique, however, is less sensitive than the transmittance technique since about 80 /o of the infrared radiation is lost after being reflected off the sample surface. 

Woo, Y.A., Terazawa, Y., Chen, J.Y. et al. (2002) Development of a new measurement unit (MilkSpec-1) for rapid determination of fat, lactose and protein in raw milk using near-infra-red transmittance spectroscopy. 56 (5), 599-604. 

Figure 9.1. Reflectance and transmittance spectroscopy. (<3) Transmittance mode (6) reflectance mode.

Sierra et al. in 2007 conducted a study for the rapid prediction of the fatty acid (FA) profile of ground using near infrared transmittance spectroscopy (MT). The samples were scanned in transmittance mode from 850 to 1050 nm. MT spectra were able to accurately predict saturated R2=0,837, branched R2=0,701 and monounsaturated R2=0,852 FAs. Results were considered interesting because intramuscular fat content and composition influence consumer selection of meat products. 

Sierra, V. Aldai, N. Castro, P. Osoro, K. Coto-Montes, A. Oliva, M (2007). Prediction of the fatty acid composition of beef by near infrared transmittance spectroscopy. Meat Science Vol.78, pp. 248-255... 

T. Burger, H. J. Ploss, Ebel, and J. Fricke, Diffuse Reflectance and Transmittance Spectroscopy for the Quantitative Determination of Scattering and Absorption Coefficients in Quantitative Powder Analysis, Appl. Spectrosc., 51(9), 1323 (1997). 

Gray scale standards of reflectance are the equivalent of neutral-density filters in transmittance spectroscopy. These materials are used in determining the linearity of detector systems for reflectance spectrophotometers. Although these materials are common in the field of photography and densitometry in the form of gray scale cards produced by Kodak and other film manufacturers, the equivalent in diffuse reflectance standards has been, until recently, difficult to produce or obtain. 

Transmittance spectroscopy and optically transparent cell materials... 

Murray, L, in The NIR Spectra of Homologous Series of Organic Compounds in Near- Infrared Diffuse Reflectance/transmittance Spectroscopy, Hollo, J., Kaffka, K.J., and Gonczy, J.L. (Eds.), Akademiai Kiado, Budapest, 1987, pp. 13-28. 

T. Tajuddin, S. Watanab, K. Harada, S. Kawano. Application of near infrared transmittance spectroscopy to the estimation of protein and lipid contents in single seeds of soybean recombinant inbred lines for quantitative trait analysis. J Near Infrared... 

B. Barabas. Comparison of measurability of two produces of high protein content. In Near Infrared diffuse reflectance/transmittance spectroscopy. Proceedings of the International NIR/NFF conference, Budapest, Hungary, May 12-16,1986. J. Hollo, et al co-eds. Akademiai Kiado, Budapest. 1987, p. 169-176. 

J. B. Misra, R. S. Mathur, D. M. Bhatt. Near-infrared transmittance spectroscopy a potential tool for non-deslructive determination of oil content in groundnuts. J Sci Food Agric 80 237-240, 2000. 

Y. S. Chen, A. O. Chen. Quality analysis and purity examination of edible vegetable oils by near infrared transmittance spectroscopy. In Near Infrared Spectroscopy Leaping ahead with Proceedings of the Sixth International Conference on Near-Infrared Spectroscopy. G. D. Batten, R C. Flinn, L. A. Welsh, A. B. Blakeney, co-eds. The NIR Spectroscopy Group, Royal Australian Chemical Institute, 1/21 Vale Street, North Melbourne, Australia, 1995, p. 316-323. 

R. Nortvedt, O.J. Torrisen, S. Tuene. Application of near-infrared transmittance spectroscopy in the determination of fat, protein and dry matter in Atlantic halibnt fillet. Chemometrics Intell Lab Syst 42 199-207, 1998. 

J.P. Wold, T. Jakobsen, L. Krane. Atlantic salmon average fat content estimated by near-infrared transmittance spectroscopy. / Food 5c 61 74-77, 1996. 

Cahioc h, T., Cameho, S., Henrard, L., Lamhin, RH., 2000, Optical transmittance spectroscopy of con-centric-shell fuflerenes layers produced hy carhon ion implantation, Eur. Phys. J. B 18, 535—540. 

T. Naes and T. Isaksson, Locally Weighted Regression of Diffuse Near Infrared Transmittance Spectroscopy, A/ / Z. Spectros., 46 34-43 (1992). 

Guiader, M., Cheese and meat analysis by NIR, International Near Infrared Diffuse Reflectance/Transmittance Spectroscopy Conference, Budapest, Hungary, May 1986. 

NIR transmittance spectroscopy was used to monitor polyurethane reaction extent in situ during a reaction injection molding (RIM) process. Good agreement was observed between multivariate (PGA) analysis, univariate (Beer-Lambert) analysis, and kinetic predictions. It was demonstrated that PGA methods with carefully chosen spectral ranges could provide estimation of the reaction extent without time-consuming calibration [83]. 

Lachenal, G, I. Stevenson, and N. Celette, Near-Infrared Transmittance Spectroscopy for Radiochemical Ageing of EPDM. Ano/ysf, 2001.126 2201-2206. 

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