30 сентября, 2015 
Pokraskin The crystal structure of the pigments is determined by X-ray analysis which is sensitive enough to determine 0.3-0.5% anatase in the presence of 99.7-99.5% rutile. For standards, see Table 1.1 (Titanium dioxide pigments; “Methods of analysis” and “Specification”).
A qualitative test for TiO2 is a blue-violet coloration of beads of microcosmic salt (NaNH4HPO4 4H2O), or a yellow-orange coloration produced when hydrogen peroxide is added to a test solution in hot, concentrated sulfuric acid containing ammonium
sulfate. For quantitative determination, the pigment is dissolved or digested in sulfuric acid and the solution is reduced to Ti3+ with cadmium, zinc, or aluminum. The Ti3+ ions are then usually titrated with a standard solution of iron(III) ammonium sulfate solution, with potassium rhodanide as an indicator, or using potentiometric end point determination.
Trace impurities can be determined by wet analysis, X-ray fluorescence, or spec — trographic analysis (e. g., atomic absorption or ICP spectroscopy).
Typical analytical data for an untreated rutile pigment are TiO2 99.4%, K2O 0.24%, P2O5 0.21%, Fe2O3 40 ppm, Sb2O3 24 ppm, Al2O3 20 ppm, Mg 5 ppm, Zn 3 ppm, Cr 2 ppm, Mn, Cu, Hg, Cd, Co, Ni, Se, Sn, Ag <1 ppm.
2.1.7
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