Author
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Reeves Iii, James |
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Submitted to: Federation of Analytical Chemistry and Spectroscopy Societies Final Program
Publication Type: Proceedings Publication Acceptance Date: 10/31/1996 Publication Date: N/A Citation: N/A Interpretive Summary: Technical Abstract: The objective was to determine the effects of water and physical state on NIRS calibrations for carbohydrate mixtures. Seventy five mixtures of cellulose, starch, pectin, locust gum, glucose and xylitol were scanned in the near-infrared in three physical states (wet, simple mixtures of dry constituents, and mixtures dried together). These final samples were prepared by drying mixtures while under constant stirring to prevent separation of the insoluble polymers by settling, which occurs during normal oven drying. Final drying of the resulting solid mass was carried out in a vacuum oven at 60o C. The dried mass was then ground and scanned in the spectrometer. Finally, all dry samples were ground to a flour like consistency using a A-10 Analytical Mill by Tekmar (Cincinnati, OH) to avoid effects due to gross differences in particle size. The wet samples were produced by adding sufficient water to result in samples of a putty like consistency. Near-infrared spectra were taken on a Digi-Lab (BIO-RAD, Cambridge, MA) FTS-65 Fourier transform spectrometer equipped with a quartz beamsplitter, halogen source, PbSe detector, and dry air purge, by diffuse reflectance, using sulfur (sublimed, 100 mesh) for the background spectra. Initial partial least squares regression results have shown that the presence of water greatly influences and limits one's ability to develop accurate PLS calibrations for even such simple systems consisting of a limited number of similar components. |
