WHITENESS OF TALCUM POWDERS AS A QUALITY INDEX FOR PHARMACEUTICAL USES

Talc is a whitish raw material of mineral origin used in the pharmaceu tical industry. Talc quality for pharmaceutical uses is regulated by p harmacopoeias, which include several chemical and physicochemical test s. The aim of this study was to relate various color parameters of twe nty-one white talcum powders from five countries, to their suitability for pharmaceutical use, following the tests included in the pharmacop oeias of USA (USP XXIII), Japan (Jap.Ph.XII) and Europe (Eur. Ph.II). The tests for loss on ignition 1000 degrees C( USP XXIII), carbonates, iron and magnesium soluble in H2SO4 IN (Eur.hh.II), and loss on dryin g 500 degrees C (Jap.Ph.XII), showed the best relationship with color parameters. The strength of these relationships allows the tests to be estimated from the color parameters or vice versa using regression mo dels, of which Z(10)-tristimulus value, lightness L and CIE whiteness index W-10 were the most influential parameters for explaining the mo dels. As an index of suitability of the talc for pharmaceutical use, W -10 proved to be the most efficient of the three color parameters with a limit value of W-10 = 68.00 for USP XXIII. (C) 1998 John Wiley & So ns, Inc.