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    Identification by Instrumental Methods of Chemical Compounds in Water-Formed Deposits

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    A combination of elemental and direct instrumental analyses has proved most successful for identifying the chemical compounds present in water-formed deposits. Qualitative X-ray diffraction analysis may be enhanced by improving resolution of lines, concentrating minor constituents, and converting amorphous compounds to crystalline form. Quantitative X-ray diffraction is accomplished with the aid of calcium fluoride as an internal standard, to compensate for absorption of X-rays by the deposit sample. Petrographic thin section techniques provide unique advantages for studying layers of deposition directly. Distinctive infrared absorption spectra have been obtained for phosphate, carbonate, and silicate compounds, which should aid in deposit identification. A wide variety of deposits undergo thermal reactions to give characteristic differential thermal analysis patterns. Thermal reactions taking place in steam atmospheres aid in the identification of hydrates; compounds which form carbonates are more easily detected in carbon dioxide atmospheres; and oxygen atmospheres bring about thermal reactions in compounds susceptible to oxidation. Although instrumental methods are extremely useful and may be expected to increase in utility, elemental analysis must still be relied on in difficult cases.

    Author Information:

    Maddin, C. M.
    Dowell Division of The Dow Chemical Co., Tulsa, Okla.

    Rosene, R. B.
    Dowell Division of The Dow Chemical Co., Tulsa, Okla.

    Committee/Subcommittee: D19.03

    DOI: 10.1520/STP46309S