Packaging and storage—
Preserve in well-closed containers.
Labeling—
If intended for UV-attenuation, the material must be labeled as attenuation grade. If intended for UV-attenuation, and any added coatings, stabilizers, or treatments are used, the labeling shall include the name and amount of the additives.
Identification—
To 500 mg add 5 mL of sulfuric acid, and heat gently. After fumes of sulfur trioxide appear, continue heating for a minimum of 10 seconds. Cool the suspension, and cautiously dilute with water to 100 mL. Filter, and to 5 mL of the clear filtrate add a few drops of
hydrogen peroxide TS: a yellow-red to orange-red color develops immediately.
Loss on ignition 
733
—
Ignite 2 g, previously dried and accurately weighed, at 800 ± 25
to constant weight: it loses not more than 0.5% of its weight. If labeled as attenuation grade, ignite 4 g of titanium dioxide, accurately weighed, at 800 ± 25
to constant weight: it loses not more than 13% of its weight.
Water-soluble substances—
Suspend 4.0 g in 50 mL of water, mix, and allow to stand overnight. Transfer to a 200-mL volumetric flask, add 2 mL of
ammonium chloride TS, and mix. If the Titanium Dioxide does not settle, add another 2-mL portion of
ammonium chloride TS. Allow the suspension to settle, dilute with water to volume, mix, and filter through a double thickness of fine-porosity filter paper, discarding the first 10 mL of the filtrate. Collect 100 mL of the clear filtrate, transfer to a tared platinum dish, evaporate on a hot plate to dryness, and ignite at a dull red heat to constant weight: the residue weighs not more than 5 mg (0.25%).
Acid-soluble substances—
Suspend 5.0 g in 100 mL of 0.5 N hydrochloric acid, and heat on a steam bath for 30 minutes, with occasional stirring. Filter through an appropriate filter medium until clear. Wash with three 10-mL portions of 0.5 N hydrochloric acid. Evaporate the combined filtrate and washings to dryness, and ignite at a dull red heat to constant weight: the residue weighs not more than 25 mg (0.5%).
Arsenic, Method I 211—
Prepare the
Test Preparation as follows. Add 3.0 g to a 250-mL conical flask fitted with a thermometer and a vapor outlet. Add 50 mL of water, 500 mg of hydrazine sulfate, 500 mg of potassium bromide, 20 g of sodium chloride, and 25 mL of sulfuric acid. Arrange to collect the evolved vapors in 52 mL of water contained in the arsine generator flask, then heat the test specimen to 90
, and maintain the temperature at 90
to 100
for 15 minutes. Add 3 mL of hydrochloric acid to the solution in the generator flask: the resulting solution meets the requirements of the test, the addition of 20 mL of 7 N sulfuric acid specified for
Procedure being omitted. The limit is 1 ppm.
Organic volatile impurities, Method IV 467:
meets the requirements.
Assay—
Accurately weigh about 300 mg of Titanium Dioxide, transfer to a 250-mL beaker, and add 20 mL of sulfuric acid and 7 to 8 g of ammonium sulfate. Mix, heat on a hot plate until fumes of sulfur trioxide appear, and continue heating over a strong flame until solution is complete or it is apparent that the undissolved residue is siliceous matter. Cool, cautiously dilute with 100 mL of water, stir, heat carefully to boiling while stirring, and allow the insoluble matter to settle. Filter, transfer the entire residue to the filter, and wash thoroughly with cold 2 N sulfuric acid. Dilute the filtrate with water to 200 mL, and cautiously add about 10 mL of ammonium hydroxide.
Prepare a zinc amalgam column in a 25-cm Jones reductor tube, placing a pledget of glass wool in the bottom of the tube, and filling the constricted portion of the tube with zinc amalgam prepared as follows. Add 20- to 30-mesh zinc to mercuric chloride solution (1 in 50), using about 100 mL of the solution for each 100 g of zinc, and after about 10 minutes, decant the solution from the zinc, then wash the zinc by decantation. Wash the zinc amalgam column with 100-mL portions of 2 N sulfuric acid until 100 mL of the washing does not decolorize 1 drop of 0.1 N potassium permanganate.
Place 50 mL of
ferric ammonium sulfate TS in a 1000-mL suction flask, and add 0.1 N potassium permanganate until a faint pink color persists for 5 minutes. Attach the Jones reductor tube to the neck of the flask, and pass 50 mL of 2 N sulfuric acid through the reductor at a rate of about 30 mL per minute. Pass the prepared titanium solution through the reductor at the same rate, and follow with 100 mL each of 2 N sulfuric acid and of water. During these operations, keep the reductor filled with solution or water above the upper level of the amalgam. Taking precautions against the admission of atmospheric oxygen, gradually release the suction, wash down the outlet tube of the reductor and the sides of the receiver, and titrate immediately with 0.1 N potassium permanganate VS. Perform a blank determination, substituting 200 mL of 2 N sulfuric acid for the assay solution, and make any necessary correction. Each mL of 0.1 N potassium permanganate is equivalent to 7.988 mg of TiO
2.
