Particle Size Distribution Of Rps

Ti-Pure® TITANIUM DIOXIDE DETERMINATION OF PARTICLE SIZE DISTRIBUTION OF RPS (“Horiba” (LA-900) Procedure) METHOD: T4400.274.03WP

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TITANIUM DIOXIDE (Ti-Pure®) Determination of Particle Size Distribution of RPS ('Horiba' (LA-900) Procedure) I. Principle The particle size of titanium dioxide is measured in dilute aqueous dispersions with a HORIBA LA-900. The `Horiba' uses Mie scatteringtheory to measure `equivalent spherical diameter' as a function of % Transmission and scattered light. The size of the particle determines where the light is scattered. Therefore, by measuring the % Transmission, Front Scatter, Side Scatter, and Back Scatter the size of the particle can be calculated. The refractive index of the buffer and the particle and primary constants relating to particle size.These constants are supplied and are called Relative Refractive Index. II. Applicability A. General This method is used to measure the particle size of insoluble materials in the range of 0.04 to 1000 microns. B. Specific This method will measure several quantities used to characterize titanium dioxide pigment. The instrument records the cumulative % of the total mass in each size increment. Theparticle size is usually represented as calculated quantities: D50 - the median diameter in microns GSD - the geometric standard deviation is defined as the square root of “Coarse Tail” (D) divided by “Fine Tail” D. Use method T4400.274.02.WP to determine PSD parameters for RPD Vantage. (Dry Finished Product) III. Limitations The material must be dispersed in the liquid medium, but not soluble init. It measures the diameters as `equivalent spherical diameter', i.e.,

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the diameter the particles would be if they were spheres. In fact, titanium dioxide particles are somewhat acicular (needle like crystals). The refractive index of the material must be known. IV. Sensitivity Precision and Accuracy A. Sensitivity No data is available. B. Precision 1. Single Operator _ The averageanalysis (X), standard deviation (s) and 95% confidence limits (95% CL) established for the single operator precision of the method were as follows: _ X RPS Vantage® D50,um RPS Vantage® GSD 0.379 1.50 s 95% CL

0.0013 ± 0.0026 0.0062 ± 0.012

The above data were calculated from 10 replicate analyses of one sample performed by one technician over a period of 7 days. 2. Multiple Operator _ Theaverage analysis (X), standard deviation (s) and 95% confidence limits (95% CL) established for the multiple operator precision of the method were as follows: _ X RPS Vantage ® D50, um RPS Vantage® GSD 0.384 1.51 s 0.0029 0.017 95% CL ± 0.0059 ± 0.033

The above data were calculated from 40 replicate analyses of one sample performed by 4 technicians in Edge Moor Control laboratory over a period of 30days.

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C.

Accuracy No study has been made; however, results have been satisfactory based upon experience.

V. Special Apparatus (Equivalent apparatus may be substituted) 1. Balance capable of weighing 100 ± 0.01 g. 2. HORIBA LA-900, Horiba Instruments Inc., 17671 Armstrong, Irvine, CA 92714, (714) 250-4811. 3. Horiba Reservoir Unit. 4. Horiba Auto Sampler. 5. Diskette (3½"),Pre-formatted for IBM PC, XT, Double-Sided (DS), High Density (HD). 6. Tubing, Masterflex Silicone, Cat. No. G-96410-15 or equivalent. 7. Sonicator tip, titanium, Cat No. 027 (pack of 5) or standard Heat Systems tip with Heat Systems unit. 8. IBM PC or equivalent. 9. Oxford Benchmater Pipette, 1001-10001, Fisher Scientific or other adjustable pipetter with comparable precision. VI. Reagents (Reagent gradeexcept as noted) 1. Tetrapotassium Pyrophosphate (TKPP), reagent grade. 2. Kodak, Photo-Flo 200, wetting agent. VII. Special Safety Considerations A. Product Hazards 1. There are no unusual product hazards.

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B. Procedure Hazards 1. Observe all appropriate procedures, including general safety rules. 2. Do not place anything, including fingers, in the path of the laser beam while it is...