Packaging and storage— Preserve in
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.
on ignition á733ñ—
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
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
Method I á211ñ—
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
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
omitted. The limit is 1 ppm.
Organic volatile impurities, Method
meets the requirements.
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 TiO2.