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  • Surface analysis of powder binary mixtures with ATR FTIR spectroscopy
    Planinšek, Odon ...
    Attenuated Total Reflectance Fourier Transform Infra Red spectroscopy (ATR FTIR) has been used for surface analysis of powder mixtures. The appearance ofone component on the surface of the mixture in ... greater amounts than that expected from the mass or volume ratio was quantified. Coloured mixtures containing methyl orange were analysed. They contained proportions of components from 0% to 100% in steps of 10%. Mixtures of non-sieved powders of methyl orange and Povidone were dark red when containing only 20% of methyl orange, indicating that particles of methyl orange were present on the surfaceof the mixture in higher amounts than expected from the mass ratios. Mixtures of methyl orange and Mg stearate, on the other hand, were a light colour, showing the presence of more Mg stearate on the surface than expected.Visual observations correlated with semiquantitative surface concentration determination by ATR FTIR spectroscopy using specific peaks of each component. Quantitative determination of components on the surface of themixture, using the Beer Lambert law, was possible when characteristic peaksfor the first component did not overlap with those of the other component. A non-linear correlation between peak height and concentration of acomponent in a mixture was explained by distribution of the particle size of components. With a small component, the larger number of particles in the samevolume allowed them to surround the larger particles of the second component. These conclusions were confirmed by preparing mixtures with non-coloured components (Povidone-Eudragitr, NaCl-Povidone, NaCl-Eudragitr). Results again correlated with the ATR FTIR spectroscopy measurements. It was additionally shown that a small proportion of finer particles can drastically influence the surface of powder mixtures, due to their large contribution to the specific surface area. ATR FTIR is thus demonstrated to be a useful methodfor studying surfaces of powder mixtures also in terms of process analytical technology (PAT).
    Source: International journal of pharmaceutics. - ISSN 0378-5173 (Vol. 319, no. 1-2, 2006, str. 13-19)
    Type of material - article, component part
    Publish date - 2006
    Language - english
    COBISS.SI-ID - 1961841