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FILE NAME Talc TALC DATE 0000 DOC TALC181 DOCUMENT DESCRIPTION Recommended Practices - Abestiform Amphibole Minerals in Cosmetic Talc - C.T.F.A. Method J4-1 C.T.F.A Method J 4-1 Asbestiform Amphibole Minerals in Cosmetic Talc Part I ray Diffraction Method . Part II Optical Microscopy and Dispersion Method (A Introduction The method which has been adopted for the detection of amphibole minerals in cosmetic talc is the generally accepted method of ray diffraction Methods which appear in the literature for the detection of fibrous amphibole such as transmission electron microscopy with selected area diffraction and electron microprobe have also been considered since they are capable of a lower level of detection than by ray diffraction However they have not been adopted since they suffer from the drawbacks that the amount of material under examination is quite small less than a microgram and the time for analysis expertise required and expense of equipment eliminates them as routine methods The methodology presented is the most practical available based on current technology The use of Transmission Electron Microscopy with Selected Area Electron Diffraction offers greater sensitivity but is not presented since it is unsuitable for normal quality control application Enrichment or concentration techniques using flotation cells have been tried as a means of improving the detection level however all efforts so far have been unsuccessful Principle The ray diffraction method is based upon the principle that when a crystalline material is placed in an ray beam a portion of the rays are diffracted by each set of atomic planes within the crystal The diffracted rays strike a scintillation counter as the sample is scanned through a prescribed angle with the resulting development of peaks corresponding to each interplanar distance d A peak with d value in the range of 8.04 to 8.85^ for a sample talc is strong evidence for the presence of amphibole in that talc The level of detection of amphibole by this method is 0.5 and above The variability of detection is caused by such factors as age and manufacturer of ray diffractometers sample homogeneity specific amphibole mineral present morphology of amphibole particle size preferred orientation etc. For these reasons the level of detection should be reported for levels above 0.5 since below this level the data has been found to be not reproducible If a statistically significant peak is found of intensity equal to or greater than that obtained for the 0.5 standard in the d range for amphibole described above then the sample must be put through the following confirming scheme + - ray Diffractometry Leach Optical Microscopy - Acid Leach and Dispersion Color Stop Amphibole absent |+ - Fibrous Morphology + Stop Amphibole absent Stop Asbestiform Amphibole absent Stop Asbestiform Amphibole present The Cosmetic Toiletry and Fragrance Association C.T.F.A Method J 4-1 Page 2 Part : Amphibole Minerals by ray Diffractometry Apparatus 1. ray diffractometer employing filtered copper a radiation horizontal or vertical goniometer with variable scan speed capability suitable talc pellet sample holder variable speed recorder electronic panel including ratemeter and variable attenuation and time constant settings 2. Hydraulic press capable of attaining a pressure of 15,000 to 24,000 lb calculated on a 3 ram 3. Mortar and pestle or grinding mill Note ) 4. Waring Blendor or equivalent blender 5. Spex Mixer or equivalent mechanical mixer 6. Sieve mesh 7. Optical microscope Note 2 8. 1...pellet press Reagents 1. Standard talc sample containing no detectable amphibole minerals 2. Standard tremolite sample at least 80 pure 3. Denatured ethanol 4. Boric acid Procedure The procedure consists of scanning under previously determined conditions a compressed pellet of the sample talc in the 11.0 to 10.0 8.85 to 8.04 ^ region for the presence of an amphibole peak There are times when it is difficult to discriminate a possible peak for amphibole over the background noise level Should the presence of a small amphibole peak above the background noise be in question it will be necessary to statistically evaluate the scan A scaler is required on the electronic panel of the ray diffractometer In order for a peak to be statistically significant the peak intensity must equal or exceed three standard deviations 30 above the average background intensity N Registered Trademark The Cosmetic Toiletry and Fragrance Association Where 30 = minimum peak intensity N = average background count = Peak C.T.F.A C.T.F.A Method J 4-1 Page 3 escum + | 10.3 10.3 10.3 + v + Tr 10.0 10.2 10.4 10.6 10.8 11.0 20 Figure 1 Determine the region of the scan in question in the Figure 1 scan a peak appears to be present in the 10.40 to 10.60 region Slow scan with cumulative pulse counting through the peak region three separate times and average the number of counts Determine a background count by scanning a region equal to of the 20 region covered by the peak immediately before and after the peak The counting time for each of these background regions will equal % the total counting time used for the peak Count each background region three times Then average each region and add the two averages to obtain the background count N The Cosmetic Toiletry and Fragrance Association A Method J 4-1 Page 4 Example In Figure 1 Peak c aan . e . ee Background Region Region B ccc c ee ... ee. e wc i ccc cc cee eeee Region 20 10.40 to 10.60 10.30 to 10.40 10.60 to 10.70 Time sec 120 60 60 Peak 10.40 to 10.60 time secs 120 120 120 Average counts 60,332 59,870 60,105 60,102 Background Region A 10.30 to 10.40 Region B 10.60 to 10.70 time secs 60 60 60 counts 28,784 28,943 28,634 28,787 time secs 60 60 60 counts 28,506 28,368 28,204 28,359 N - 28,757 + 28,359 - 57,146 ~ 57,146- 239 30 - 717 N + 30 - 57,146 + 717 ~ 57,863 The actual number of counts obtained for the integrated peak intensity was 60,102 therefore the suspect peak is statistically present in the scan Standard Preparation Optimal instrument conditions must first be determined with the use of tremolite standards 1.0 0.75 0.5 tremolite by weight prepared in a standard talc which is free of interfering peaks in the 11.0 to 10.0 region Weigh out appropriate amounts of standard talc and tremolite both of which have been ground to pass a 325mesh sieve Transfer to a Waring Blendor Add 100 ml of ethanol to the blender and blend at low speed for 5 minutes Carefully transfer the contents of the blender with repeated ethanol washings into a large beaker Evaporate the ethanol on a steam bath Shake the sample in a plastic vial for 5 minutes on a Spex Mixer to remove clumps and caked sample resulting from the evaporation of ethanol Determine by microscopy the homogeneity of the prepared standard previous to the ray diffraction analysis Press the homogeneous standard into a 1...pellet with a backing of boric acid Transfer 2 0.2 g of standard to the holder and evenly distribute on a polished scratch die Distribute 4 0.2 g of boric acid evenly on the talc layer Press the mixture into a pellet under conditions suitable for obtaining a smooth planar surface for example a pressure of 15,000 to 24,000 lb calculated on a 3 ram has been found to produce suitable pellets The resulting pellet must have a talc face which is free of flaws if not the pellet must be discarded Note 3 Prepare two acceptable pellets from each standard Registered Trademark The Cosmetic Toiletry and Fragrance Association A Method J 4-1 Page 5 Sample Preparation Prepare two pellets from each sample in the manner described for the standard pellets Make a qualitative scan from 4 to 50 on one of these pellets to ascertain the presence of amphibole above the % level or the presence of mineral impurities having interfering peaks in the 11.0 to 10.0 8.85 to 8.04 ^ region of the scan The presence of such interference will eliminate use of the ray diffraction method for the sample and one will have to proceed directly to the microscopical procedure Instrumentation Instrumental variables are optimized on the % standard Lower standards are then analyzed under the optimum conditions to determine the lower level of detection Of major Importance in obtaining maximum instrument sensitivity are a slow diffractometer speed combined with compatible recorder speed and high attenuation combined with a statistically acceptable time constant on the ratemeter Under appropriate instrumental conditions the peak obtained for the 0.5 standard should be detectable above background noise as shown in Figure 2 Typical instrumental conditions employed for the Siemens Diffractometer Model No. M386 and Counter and Recorder Unit Type T are Radiation Divergence slit Goniometer speed Recorder Speed Attenuation Time constant Cu with K filter at 40 KV and 24 ma Receiving slit 0.2 mm minute 300 hour x 10impulses T= Statistical error of 1.1 under these conditions Rise Time = 0.18 Attenuator = 20 The Cosmetic Toiletry and Fragrance Association 100- 90-08 7050 50 Imensity 40- F.A Method J 4-1 Page 6 0.5 Tremolite In Talc 1 t ' . 100 102 104 106 108 110 + : 8 100 102 104 106 108 110 114 '20 Figure 2 Ray Diffraction Scans Place the standard or sample pellet in a suitable holder and slowly scan between 11.0 and 10.0 Then rotate the pellet 90 with respect to its original position in the goniometer and rescan between 11.0 and 10.0 since pellet orientation may affect peak intensity The presence of a reproducible peak or peaks is due to the presence of amphibole mineral or minerals the absence of peaks in this region indicates the absence of amphibole in the sample within the limit of detection of this technique Report results as None detected or as Detected approximately % level where X equals the level detected The Cosmetic Toiletry and Fragrance Association T Method J 4-1 Page 7 Part II Asbestiform Amphibole Minerals by Optical Microscopy and Dispersion Apparatus 1. Polarizing microscope Best results will be obtained if the instrument includes the following a Individually centering objectives b Bertrand lens c intensity light source d Centering condenser 2. Dispersion device Note 4 3. Vacuum filtration equipment including either a porcelain cone with glass fiber filter mat or a porous glass bottom cup Reagents 1. Hydrochloric acid % v 2. Cargille immersion liquid Series HD 25 -- = 1.605 Note 5 Procedure Acid Treatment Because of the interference caused by some carbonates e.g. calcite in the detection of asbestiform amphiboles in talc by optical microscopy it is necessary to first remove these carbonates by a simple acid leaching procedure Weigh out 2 g of the talc into a 100 ml beaker Add 25 ml of 10 v HCI slowly to prevent excessive evolution of gas if carbonates are present and heat with occasional stirring on a steam bath for 30 minutes Filter with vacuum filtration equipment and wash several times with hot water Dry the talc Optical Microscopy and Dispersion Carefully disperse 0.1 mg of talc in one drop of Cargille HD liquid no = 1.605 and cover with a clean cover slip Examine the sample in the dispersion central stop mode The substage diaphragm should be almost completely closed the field diaphragm may be partially closed to enhance color contrast and the polarizer should be in position Tremolite actinolite and presumably other amphibole minerals under these conditions will show the following dispersion colors yellow changing to blue with rotation of the sample relative to the polarizer or yellow changing to orange with rotation The variation of the color change is due to the fact that the tremolite may lie in one of two positions relative to its principal optical orientation The Cosmetic Toiletry and Fragrance Association T Method J 4-1 Page 8 Examine the sample for asbestiform fibrous amphibole minerals In order for an amphibole mineral to be considered asbestiform fibrous it must meet the following OSHA definition Reference 4 1. Particles must appear to be fibrous rather than as crystals or slivers The maximum diameter of a fiber to be counted in 3 microns 2. The maximum length of a fiber to be counted in 30 microns 4. The length to width ratio must be 5 or more to 1 that is 5 times or more longer than wide The separate or individual fibers must contain fibrils or the bundle of sticks effect unless they are at nondivisible stage A fibril cannot be subdivided and would be counted if it meets the other criteria The length to width ratio of 5 or more to 1 is not meant to imply that other particles are not hazardous Report results as Asbestiform Amphibole Present or as Asbestiform Amphibole Absent It is imperative that both dispersion color and fibrous morphology criteria be satisfied before identifying a particle as asbestiform amphibole since other substances may show colors similar to those described Notes 1. Talcs to be analyzed and the tremolite used to prepare standard samples must be finer than 325 mesh maximum particle size of 44 microns The Tekmar Analytical Mill Model 10 is available from Tekmar Company P.O. Box 37202 Cincinnati Ohio 45222 2. It is important that the homogeneity of the prepared tremolite standard samples be verified by optical microscopy 3. This requirement is critical since excessive surface scatter will cause abnormally high background count 4. The only commercially available dispersion device is available from Walter C. McCrone Associates Inc. 2820 South Michigan Avenue Chicago Illinois 60616 5. Available from R. P. Cargille Laboratories Inc. Cedar Grove New Jersey 07009 -or from laboratory suppliers References 1. Rohl A. N. Langer A. M. Environmental Health Perspectives 9 95 1974 Rubin I. B. Maggiore C. J. Environmental Health Perspectives 9 81 1974 3. L. S. Birks Ray Spectrochemical Analysis pages 54-55 Interscience Publishers 1959 Tremolite and Talc U. S. Department of Labor Occupational Safety and Health Administration Field Information Memorandum 74-92 November 21 1974 ***** ***** ***** ***** ***** The Cosmetic Toiletry and Fragrance Association