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Philip Morris

Titanium Dioxide in Paper (Manual Colorimetric Procedure)

Date: Aug 1983
Length: 5 pages
2050799219-2050799223
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Author
Baker, P.G.
Characteristic
EXTR, EXTRA
Type
MANU, MANUAL, HANDBOOK, CATALOGUE
BIBL, BIBLIOGRAPHY
LPRO, LAB PROTOCOL
Site
R100
Master ID
2050799046/9391

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Stmn/R1-082
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Area
CENTRAL FILES/DATABASE CORRESPONDENCE
Date Loaded
23 May 1999
UCSF Legacy ID
ttu81f00

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Page 1: ttu81f00
Method Number P-21 TITANIUM DIOXIDE IN PAPER (MANUAL COLQRIMETRIC PROCEDURE) I. INTRODUCTION AND SUMrL4RY Titanium dioxide (Ti02) is determined quantitatively in paper by a colorimetric procedure which utilizes the titanium dioxide hydrogen peroxide complex. A sample of paper is cut into strips and ashed in platinum in a muffle furnace for 2.5 hours at 525°C. The ash is dissolved with ammonium sulfate and concentrated sulfuric acid by boiling. Iron (Fe{3) found in some tipping papers gives a color reaction with hydrogen peroxide but is converted to a colorless compound by the addition of phosphoric acid. The standard curve obeys Beer's law in the range of 25-75 ppm. The method can be automated using a Technicon AutoAnalyzer procedure (Method Number P-22). The relative standard deviation at the 2-sigma level is ±3% for a sample containing 20% Ti02. Recovery of titanium dioxide added to cigarette paper averaged 99%. II. SAMPLE REQUREMENTS Total sample recommended: 2 grams Sample recommended per determination: 0.500 gram Replicate determinations normally made: 2 Man-hours per determination: 1 hour Man-hours for replicates: 1.5 hours/2 determinations Total elapsed time: 8 hours
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2 III. APPARATUS AND REAGENTS A. Apparatus Method Number P-21 l. Crucibles, platinum, approximately 25 mL capacity with flat style platinum covers. 2. Lindberg Hevi Duty furnace or equivalent.- 3. Bausch and Lomb "Spectronic 21" or equivalent spectrophoto- meter, with matched cuvettes. 4. Nuova II stirring/heating plate or equivalent stirring hot plate. B. Reagents 1. Ammonium sulfate, (NH4)2SO4i ACS grade. 2. Hydrogen peroxide solution, 3%. Dilute 100 mL of 30% H202, reagent grade, to one liter with distilled water. Prepare fresh daily. Refrigerate 30% H202 after opening. CAUTION: HANDLE WITH CARE. Hydrogen peroxide is a strong oxidant and can cause severe skin.or eye injury. 3. Sulfuric-phosphoric acid solution. Carefully add with constant stirring 500 mL of 36N H2S04 to 300 mL of distilled water in a one-liter Erlenmeyer flask positioned in an ice bath. Cool to room temperature. Continue to stir and add 200 mL of 85% H3P04 to the flask contained in the ice bath. Cool to room temperature. CAUTION: Extreme heat is produced upon addition of acids. Titanium dioxide (TiOZ), stock standard solution. 500 Pg/mL. a. Dry a portion of Ti02. Heat at 150°C for 16 hours or overnight. Store in a desiccator.
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3 Method Number P-21 b. Weigh 0.I000g ± 0.1 mg of dry Ti02 and transfer to a 250 mL beaker. c. Add 8g ammonium sulfate and 20 mL of 36N H2SO4 and cover with a ribbed watch glass. d. Heat with constant stirring on a magnetic stir plate to near boiling. Solution will change from milky white to clear or greenish yellow. e. Cool to room temperature and add 90 mL distilled water. f. Cool to room temperature and filter through Whatman #41 filter paper into a 200 ml volumetric flask. Dilute to volume with distilled water. IV. PROCEDURE The paper is ashed at 525°C and the ash is dissolved with 8g of ammonium sulfate in 20 mh of 36N H2SO4. Phosphoric acid is added to complex iron (Fe+3 ) and the solution is reacted with H202. Standards and samples must be prepared with the same batch of freshly prepared 3% H20. The absorbance of standard and sample solutions is measured at 420 nm. The concentration in pg/mL Ti02 in sample solutions is determined from a calibration curve prepared from standards with each series of samples. Once color development has occurred color is stable for 1 week. A. Preparation of Standard Curve 1. Pipette into separate 100-mL volumetric flasks 0, 5, 10, and 15 mL stock Ti02 solution. 2. Add 10 mL of the sulfuric-phosphoric acid mixture using a tl-z O Repipet and 10 mL 3% H202. Dilute to volume and mix. These CS! O standards will contain 0, 25, 50, and 75 pg/mL Ti02 respec- ti C,D tively. ~ ~ ~
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4 Method Number P-21 3. Pour a portion of each working standard into separate cuvettes. 4. Read absorbance at 420 nm using "0" pg/mL standard as ref- erence. ~ 5. Plot a standard curve of concentration vs absorbance. B. Preparation of Samples 1. Cut paper into 1 cm strips. 2. Weigh to the nearest lmg about 0.500g of paper into a platinum crucible. 3. Place into a muffle furnace and bring temperature to 250°C. Heat at 250°C for 15 minutes. 4. Raise the temperature to 525°C and continue to heat for 2.5 hours. 5. Remove from furnace and allow to cool. 6. Transfer the ash to a 250-mL beaker containing 8g ammonium sulfate. 7. Add 20 mL of 36N H2SO4 and cover with ribbed watch glass. 8. Heat with constant stirring on a magnetic stirrer to near boiling. Solution will change from milky white to clear or greenish yellow. 9. Cool and add 90 mL distilled water. 10. Cool to room temperature and filter through Whatman #41 filter paper into a 200-mL volumetric flask. 11. Add 20 mL of the sulfuric-phosphoric acid mixture using a 12. Repipet. Add 20 mL 3% H202. ~ © C32 Dilute to volume with distilled water. O ~ CD
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5 Method Number P-21 13. Pour a portion into a cuvette and measure absorbance at 420 nm. 14. Read the concentration in pg/mL of Ti02 from the standard curve. If the concentration of the sample solution is greater than the highest standard, the sample solution may be further diluted with distilled water. V. CALCULATION % Ti02 =pg/mL Ti02 x 200 mL x 100 (4) x .001 (pg to mg) nmg Sample VIII. REFERENCES 1. Baker, P. G. Memo to K. Gunst, "Colorimetric Determination of Titanium Dioxide (Ti02) in tipping paper", March 29, 1983. 2. Handy, B. M., Completion Report Accession No. 72-061, July 6, 1972. 3. Walker, G. B. Jr., Handy, B. M. Analytical Method Number 1-15, July, 1972. 4. Project Book 7183, p. 162-3. fc~- , P. G. Baker August, 1983

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