Document xjopkjZ58n1qN5YxVKyn3v7jb

FILE NAME: CTFA (CTFA) DATE: 1975 Oct 7 DOC#: CTFA014 DOCUM ENT DESCRIPTION: CTFA M eth o d Paper CTFA Method J 4-1 Issuec: 10-7-75 Page' ASBESTIFORM AMPHIBOLE MINERALS IN COSMETIC TALC Part I: X-ray Diffraction Method Part It; Optical Microscopy and Dispersion-Staining Method Introduction The method which has been adopted for the detection of amphibole minerals ir cosmetic talc is the generally accepted method of x-ray diffraction. Methods which appear in the literature for the detection of fitrous amphibole, such as, transmission electron microscopy witn selected area diffraction' and electron microprobe,1 have aiso been considered since they are capable of a lower level of detection than by x-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 x-ray diffraction method is based upon the principle that when a crystalline material is placed in an x-ray beam, a porticn of the x-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 interpfanar distance (d). A peak with d value in the range of 8.04 to 8.85A0 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 C.5% and above. The variability of*detection is caused by such factors as age and manufacturer of x-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: X-ray Diffractom etry <+) --> Optical Microscopy (-) -> Stop (Amphibole absent) (Add Leach) and I " ) Dispersion-Staining Color Stop (Amphibole absent) I (+) Fibrous Morphology----(-----)-- ^ Stop (Asbestiform Amphibole absent) (+ ) Stop (Asbestiform Amphibole present) COSMETIC, TOILETRY AND FRAGRANCE ASSOCIATION,INC. * 1 1 3 3 Fifteenth Street,N.W., Washington, D.C. 20005 CTFA Method J 4*1 ssued TP0a-7g-e75s Part i; Amphibole Minerals by X-ray Diftractometry Apparatus 1. X-ray diffractometer, employing nickel-filtered copper..K-alpha 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 1) 4. Waring Blendor,* or equivalent blende' 5. Spex Mixer/Mill,' or equivalent mechanical mixer 6 Sieve, 325-mesh 7. Optica! microscope (Note 2) 8. 1 peliet press Reagents 1. Standard talc sample, containing no detectable amphibole minerals 2. Standard tremolite sample, at least 80% pure Sample of tremolite standard may be obtained by ordering 1rom The Cosmetic Toiletry and fragrance Associa tion, Inc., 1133 Fifteenth Street, N.W., Washington, D.C. 20005. 3. Denatured ethanol .. .. fissmt: t=s= 4. Boric acid Procedure The procedure consists of slow-scanning, under previously determined conditions, a compressed pellet of the sample taic in the 11.0 to 10.028 (8.85 to 8.04 A) region for the presence of an amphibole peak. There are times when it is difficult to discrimi nate a possible peak for amphibole over the background noise level. Registered Taaemark COSMETIC, TOILETRY AND FRAGRANCE ASSOCIATION, INC. - 3J33 Fifteenth Street. N.W.. Washinefnr n r "Xinoc CTF Method J 4-1 Issued' 10-7-75 Paoe 3 Should tne presence cl a smal! amphibole peak above the background "noise" be In Question, it will be necessary lo statistically evaluate the scan. A timer/scaler is required on the electronic panel o` the x-ray diffractometer, in orcer for a peak to Pe statistically significant, the peak intensity must equal or exceed three stancarti deviations (3a) above the average background intensity (N): Where: N + 3 a = minimum peak intensity N = average background count ir = V N Determine the region of the scan in question: in the Figure 1 scan, a peak appears to be present in the 10.40 to 1O.6C20 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 Vj of the "26 region covered by.the peak, immediately before and after the peak. The counting time for each of these background regions will equal Vi 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). COSMETIC, TOILETRY AND FRAGRANCE ASSOCIATION, INC. - 1133 Fifteenth Street,N.W., Washington, D.C. 20005 Example: In Figure *. Peak .................. ... Background Region A . ........ Region B ............ .......... Region (2 % 10.30 to 10.40 Time (sec.) 120 - 60 60 Peak 10.40 to 10.60*26 time secs, counts 120 120 120 Average 60,332 69,870 60,105 60,102 Backaround Region A Region B 10.30 to 10.40*26 10.60 to 10.70 26 time secs, counts time secs, counts 60 28,784 60 28,943 60 28,634 28,787 60 28,506 60 28,368 60 28,204 28,359 CTF Method J 4-1 tssuo: 10-7-76 capfi 4 N = 28,787 + 28,359 = 57,146 <r = V 57,146 239 3cr = 717 N + 3<r = 7,145 + 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. COSMETIC, TOILETRY AND FRAGRANCE ASSOCIATION, INC. 1133 Fifteenth Street,N.W., Washington, D.C. 20005 CTFA Method J 4-1 issjefl 1P0a-/g-7eB5 Standard Preparation Optimal instrument conditions must first be determined with the use o! trerrolite standards; 1.0%, 0.75%, 0.5% tremolite by weight, oreparec ir a standard talc which is free of interfering peaks in the 11.0 to 1C.O20 region. Weigh out appropriate amounts of standard laic and tremolite both of which have been ground to pass a 325-mesh 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 lor 5 minutes on a Spex Mixer/Mill* to remove clumps and caked sample resulting from the evaporation of ethanol. Dete-mine by microscopy the homogeneity of the prepared standard previous to the x-ray diffraction analysis. Press the homogeneous standard into a 114" pellet with a backing of boric acid. Transfer 2 ( 0 .2 ) g of standard to ine die-holder and evenly distribute on a polished, scratch-free die. Distribute 4 ( 0 .2 ) g of boric add evenly on the talc layer. Press the mixture into a pellet under conditions suitable for obtaining a smooth pianar surface (for example, s pressure of 16,000 to 24,000 lb calculated o r a 3" ram has beer 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 (Mote 3). Prepare two acceptable pellets from each standard. Registered T-ademarK COSMETIC, TOILETRY AND FRAGRANCE ASSOCIATION. INC. 1133 Fifteenth Street.N.W.. Washington, D.C. 20005 CTFA Method J 4-1 Issued 10-7-76 Pace 6 Sample Preparation c:. Prepare two pellets from each sample in the manner describee tor the standard pehets, Make a qualitative scan':: 'rom 4 to 50 '2 6 on one ot these pellets to ascertain the presence ot amphibole above the 2% level or the presence ot mineral impurities having interfering peaks in the 11.0 to 10.C "26 (8.85 to 8.04) region of the scan. The presence ot such interference will eliminate use of the x-ray diffraction method lor the sampie, and one will have to proceed directly to the microscopical procedure. instrumentation Instrumental variables are optimized on the 1% 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 dif fractometer speed combined with compatible recorder speed, and high attenua tion combined with a statistically acceptable tin e constant on the ralemeter. 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-X-A4), and Counter and Recorder Unit (Type T) are; Radiation: Divergence slit: Goniometer speed: Recorder speed: Attenuation: Time constant: Cu with Kbfilter at 40KV and 24 ma 1 Receiving slit: 0.2 mm ViD26/minute 3O0mm/hour 1 x to3impulses/second T{s)-4 Statistical error of 1.1% under these conditions Rise Time = 0.18 Attenuator = 20 COSMETIC, TOILETRY AND FRAGRANCE ASSOCIATION, INC. 1 1 3 3 Fifteenth Street, N.W. Washington, D.C. 20005 0.5% Tremolite In Talc CTFA Method J 4-1 Issued: 151-7- n Page 7 9t,6 t 10i.0 l1C5t 10.4 10*.6 10I 11.I0 I H.4 Figure 2 X-Ray Diffraction Seans Place the standard or sample pellet in a suitable holder and slowly scan between 11.0 and 1O.O20. Then rotate the peliet 90 with respect to its original position in the goniometer and rescan between 11.0 and 1O.CT20 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 ot peaks in this region indicates the absence of amphibole in the sample, within the limit of detection ot this technique. Report results as "None detected" or as "Detected at approximately X% level.." where "X" equals the level detected. COSMETIC, TOILETRY AND FRAGRANCE ASSOCIATION, INC. 1133 Fifteenth Street, N.W., Washington, D.C. 20005 CTFA Method J 4-1 issued: 1P0a*g7e-76 ' .v Part li: Asbestiform Amphibole Minerais by Optica! Microscopy and Dispersion-Staining Apparatus 1. Polarizing microscope. Best results will be obtained if the instrument includes the following: a Individually centering objectives b. Bertrand lens c. High-intensity light source d Centering condenser/substage 2. Dispersion-staining 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, 10% v/v 2. Cargille immersion liquid Series HD, n" ' = 1,605 (Note 5) Procedure Acid Treatment Because of the interference caused by some carbonates (e.g. calcite) in the detec tion of asbestiform amphiboles in talc by optical microscopy/dispersion-staining: it is necessary tc first remove these carbonates by a simple acid leaching procedure: COSMETIC, TOILETRY AND FRAGRANCE ASSOCIATION, INC. - 1133 Fifteenth Street, N.W., Washington, D.C. 20005 CTFA Method J 4-1 issued: 10-7-76 Page 9 Weigh out 2 g of the talc into a 100 ml beaker Add 25 ml of 10% v/v HCI slowly (to prevent excessive evolution of gas if carbonates are present) and heat, with occasional stirring on a steam batn for 30 minutes. Fitter with vacuum filtration equipment, and wash several times with hot water. Dry the talc. Optical Microscopy and Dispersion-Staining Carefully disperse 0.1 mg of talc in one drop of Cargllle HD liquid, rfD5"= 1.605, a id cover with a clean cover slip. Examine the sample in the dispersion-staining central stop mode The substage diaphragm should be almost com pletely closed, the field diaphragm may be partially closed to enhance coor contrast, and the polarizer should be in position. Tremclite, actinolite and presumably other amphibole minerals, under these condi tions, will show the following dispersion-staining 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 Ci two positions relative to its principal optical orientation. Examine the sample for asbestiform fibrous amphibole minerals. in order for an amphiboie 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. 2. The maximum diameter of a fiber to be counted in 3 microns. 3. The maximum length of a fiber to be counted is 30 microns. 4. The length to width ratio must be 5 or more to 1, that is, 5 times or more longer than wide. 5. The separate or individual fibers must contain fibrils or the "bundle of sticks" effect, unless they are at a 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. COSMETIC, TOILETRY AND FRAGRANCE ASSOCIATION INC. 1133 Fifteenth Street,N.W., Washington, D.C. 20005 CTFA Method J 4-1 Issutili. 19-7-76 Pase 10 Report results as ``Asbesfiform Amphibole Present" or as "Asbestiforrr Amphibole Absent." It is imperative that both dispersion-staining color and fibrous morpnology criteria be satisfied before identifying a particle as asbestiform amphibole, since other sub stances 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 (maxi mum particle size of 44 microns). The Tekmar Analytical Mill (Model A-10) Is recommended. It is available from: Tekmar Company P.O. Box 37202 Cincinnati, Ohio 45222 2. It is important that the homogeneity of the prepared tatc-tremolite standarc samples be verified by optical microscopy. 3. This requirement is critical since excessive surface scatter will cause abnormally high background counts. 4. The only commercially available dispersion-staining device is sold by: Walter C. McCrone Associates, Inc. 2620 South Michigan Avenue Chicago, Illinois 60616 5. Available from: -- or from laboratory suppliers. R. P. Cargille Laboratories, Inc. Cedar Grove, New Jersey 07009 References 1. Rohl, A. N., Langer, A. M., Environmental Health Perspectives 9 ,95 (1974) 2. Rubin, I. B,, Maggiore, C. J,, Environmental Health Perspectives 9, 81 (1974) 3. L. S. Birks, X-Ray Spectrochemical Analysis, pages 54-55, Interscience Publishers (1959) 4. "Tremolite and Talc." U.S. Department of Labor, Occupational Safely and Health Administration, Field Informa tion Memorandum # 7 4 -9 2 , November 21,1974. r COSMETIC, TOILETRY AND FRAGRANCE ASSOCIATION, INC. - 1 1 3 3 Fifteenth Street, N.W., Washington, D C 20005 CTFOROIALSGEMTRREAYTN*ITMCCE*, A S S o o m a v iN a Enclosed is the information which you requested. Please contact CTFA if we can be of further assistance. 1133 15th ST., N.W., WASHINGTON, O.C. 20005 * 202/ 331-17TO TELEX S8 -2073 m 9%