Titanium oxide (TiO2).
Titanium oxide (TiO2) [13463-67-7].
»Titanium Dioxide contains not less than 99.0percent and not more than 100.5percent of TiO2,calculated on the dried basis.If labeled as attenuation grade,then Titanium Dioxide contains not less than 99.0percent and not more than 100.5percent of TiO2,calculated on the ignited basis.Attenuation grade material may contain suitable coatings,stabilizers,and treatments to assist formulation.
NOTEIf labeled as attenuation grade,then all tests and assays are conducted on uncoated,untreated material.For UVattenuation grade,the test for Loss on drying does not apply.The FDArequires the content of lead to be not more than 10ppm,that of antimony to be not more than 2ppm,and that of mercury to be not more than 1ppm (21CFR73.1575).
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 500mg add 5mLof sulfuric acid,and heat gently.After fumes of sulfur trioxide appear,continue heating for a minimum of 10seconds.Cool the suspension,and cautiously dilute with water to 100mL.Filter,and to 5mLof the clear filtrate add a few drops of hydrogen peroxide TS:a yellow-red to orange-red color develops immediately.
Loss on drying á731ñ Dry it at 105for 3hours:it loses not more than 0.5%of its weight.
Loss on ignition á733ñ Ignite 2g,previously dried and accurately weighed,at 800±25to constant weight:it loses not more than 0.5%of its weight.If labeled as attenuation grade,ignite 4g of titanium dioxide,accurately weighed,at 800±25to constant weight:it loses not more than 13%of its weight.
Water-soluble substances Suspend 4.0g in 50mLof water,mix,and allow to stand overnight.Transfer to a 200-mLvolumetric flask,add 2mLof ammonium chloride TS,and mix.If the Titanium Dioxide does not settle,add another 2-mLportion 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 10mLof the filtrate.Collect 100mLof 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 5mg (0.25%).
Acid-soluble substances Suspend 5.0g in 100mLof 0.5Nhydrochloric acid,and heat on a steam bath for 30minutes,with occasional stirring.Filter through an appropriate filter medium until clear.Wash with three 10-mLportions of 0.5Nhydrochloric 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 25mg (0.5%).
Arsenic,Method Iá211ñ Prepare the Test Preparationas follows.Add 3.0g to a 250-mLconical flask fitted with a thermometer and a vapor outlet.Add 50mLof water,500mg of hydrazine sulfate,500mg of potassium bromide,20g of sodium chloride,and 25mLof sulfuric acid.Arrange to collect the evolved vapors in 52mLof water contained in the arsine generator flask,then heat the test specimen to 90,and maintain the temperature at 90to 100for 15minutes.Add 3mLof hydrochloric acid to the solution in the generator flask:the resulting solution meets the requirements of the test,the addition of 20mLof 7Nsulfuric acid specified for Procedurebeing omitted.The limit is 1ppm.
Organic volatile impurities,Method IVá467ñ: meets the requirements.
Assay Accurately weigh about 300mg of Titanium Dioxide,transfer to a 250-mLbeaker,and add 20mLof sulfuric acid and 7to 8g 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 100mLof 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 2Nsulfuric acid.Dilute the filtrate with water to 200mL,and cautiously add about 10mLof 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 (1in 50),using about 100mLof the solution for each 100g of zinc,and after about 10minutes,decant the solution from the zinc,then wash the zinc by decantation.Wash the zinc amalgam column with 100-mLportions of 2Nsulfuric acid until 100mLof the washing does not decolorize 1drop of 0.1Npotassium permanganate.
Place 50mLof ferric ammonium sulfate TSin a 1000-mLsuction flask,and add 0.1Npotassium permanganate until a faint pink color persists for 5minutes.Attach the Jones reductor tube to the neck of the flask,and pass 50mLof 2Nsulfuric acid through the reductor at a rate of about 30mLper minute.Pass the prepared titanium solution through the reductor at the same rate,and follow with 100mLeach of 2Nsulfuric 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 0.1Npotassium permanganate VS.Perform a blank determination,substituting 200mLof 2Nsulfuric acid for the assay solution,and make any necessary correction.Each mLof 0.1Npotassium permanganate is equivalent to 7.988mg of TiO2.
Auxiliary Information Staff Liaison:Justin Lane,B.S.,Scientific Associate
Expert Committee:(EMC)Excipients:Monograph Content
USP28NF23Page 1937Pharmacopeial Forum:Volume No.30(4)Page 1301