title: Local and average gloss from flat-faced sodium chloride tablets.
abstract: The purpose of this study was to detect local gloss and surface structure changes of sodium chloride tablets. The changes in surface structure were reflected by gloss variation, which was measured using a diffractive optical element-based gloss-meter (DOG). By scanning a surface area, we constructed a 2-dimensional gloss map that characterized the tablet's surface structure. The gloss variation results were compared with scanning electron microscopy (SEM) images and average surface roughness values that were measured by conventional diamond stylus profilometry. The profilometry data showed a decrease in tablet surface roughness as a function of compression force. In general, a smoother surface contributes to higher average gloss values. The average gloss values for this material, in contrast, showed a decrease as a function of the compression force. The sequence of particle fragmentation and deformation together with crack formation in sodium chloride particles resulted in a loss of gloss for single sodium chloride particles at the tablet surfaces, which could be detected by the DOG. These results were supported by the SEM images. The results show that detailed information regarding tablets' surface structure changes can be obtained by detection of local gloss variation and average gloss.
authors.affiliation: Department of Physics, University of Joensuu, PO Box 111, FI-80101, Joensuu, Finland. mikko.juuti@joensuu.fi.
authors.forename: Mikko
authors.initials: M
authors.lastname: Juuti
authors.affiliation: Orion Pharma R&D, Orion Corporation, PO Box 425, FI-20101, Turku, Finland.
authors.forename: Bert
authors.initials: B
authors.lastname: van Veen
authors.affiliation: Department of Physics, University of Joensuu, PO Box 111, FI-80101, Joensuu, Finland.
authors.forename: Kai-Erik
authors.initials: KE
authors.lastname: Peiponen
authors.affiliation: Department of Pharmaceutics, University of Kuopio, PO Box 1627, FI-70211, Kuopio, Finland.
authors.forename: Jarkko
authors.initials: J
authors.lastname: Ketolainen
authors.affiliation: Department of Chemistry, University of Joensuu, PO Box 111, FI-80101, Joensuu, Finland.
authors.forename: Valtteri
authors.initials: V
authors.lastname: Kalima
authors.affiliation: Department of Physics, University of Joensuu, PO Box 111, FI-80101, Joensuu, Finland.
authors.forename: Raimo
authors.initials: R
authors.lastname: Silvennoinen
authors.affiliation: Department of Chemistry, University of Joensuu, PO Box 111, FI-80101, Joensuu, Finland.
authors.forename: Tuula T
authors.initials: TT
authors.lastname: Pakkanen
keywords: gloss; sodium chloride; surface structure; tablet