Document M45O9J0KGjMGGzd4LQz8OpRNa

September 2B, 1573 (b) (5) nr. Christopher K. Coafcllc Associate Director of Research Research, and Development Dopar insane Colgate - 5.bool iva Company 90 River Road ?i*eatsway, Hew Jersey SSS54 Colgate - Palmolive Company New York, New York a f # 13-716 . Dear Dr* Costello: his is in reply to your letter of Se-otesnbor 6 , 1973 which included a reeaarch report on the v.-ray diffract ion datar tarnation of chryaorile asbestos is tale In reviewing the enclosed research report, it it obvious that Dr. Slake and his associ*ics have devoted a great deal of iim* and effort in this preparation. I am sure the stechod will he -if ve liable aseistaeee to us In fha development of our aethodisliigy* We ate now in the process of installing, an x-ray diffraction nit in the F M Laboratories. When instaH a t -lop it: captoieted# *-5r* Stuart m i l start work using Dr. Sisko1* method as a reference* it* way, *e you suggest, wish to dificuss some asiaci of the method with Dr. $ `rako. If we will contact you to tsike the necessary arrangementb . In closing, X would like to- thank you for the research report and to expire ay appreciation for the effort that you and your staff have devoted to this problem* Inly by cooperation of industry and goveraswat can the enoraous task jf protectig the canaamer fee .meccwpliaHed. S :ncerely ymir&, (b) (5)Robert K, Scimi*r, Ph.S. Director, Office of technology bods * COLGATE-PALMOLIVE COMPANY Research and Development Department 909 River Road, Piscataway, N. J. 08854 CHRISTOPHER H. COSTELLO A ssociate Director of Research September 6 , 1973 Dr. Robert Schaffner Deputy Director - Office of Technology Bureau of Foods - FDA Building 8 Food <pnd Drug Administration 5600 Fishers Lane Rockville, Maryland 20852 Dear Dr. Schaffner: Ever since the question of asbestos in talc came up approximately two years ago, our Analytical people at Colgate have been study ing the problem in an effort to determine meaningful methods of detection of asbestos. Our people have had several conferences with Dr. Lewin and other experts in this area prior to launching this program. In addi tion our company has acquired a step-scanning capability for our X-ray diffraction apparatus. Yesterday J, received the final re port on the development of a method for the determination of cry- sotile asbestos in talc which-.is estimated to-have a lower limit of detection of 0.2^. r I not 3 from the PINK SHEET of August 27 that FDA has acquired the services of Dr. John W. Stuart to undertake a program to try to identify asbestos in talc through both differential thermal analy sis and X-ray diffraction. It occurs to us that the work of our Dr. Simko and his associates would be most helpful to Dr. Stuart in his work and we are therefore sending several copies of our research report on this subject in the hope that you will finu it useful. We intend to publish this work eventually,but in the interim we would be happy to have Dr. Simko discuss his work with Dr. Stuart, or whomever you might designate, pr. Simko will be willing to go to Washington for this purpose. We would welcome Dr. Stuart here also. Until a more sensitive method is determined, it is our intention to use this method as a basis for establishing standards for Colgate talc. i * Dr. Herbert Sehaffner 2 September 6 , 1973 Please let me hear from you in regard to this matter. I am sending a copy of the research report to Dr. Alfred Weissler as well be cause of his involvement in this problem in the past. I trust you will both find the report of interest. Very truly yours, .2 ~ U (b) (5) C, H. Costello 1, c Colgate-Palmolive Company Research and Development Department Piscatavay, New Jersey August 15, 1973 Research Report 2675 (Analytical Method) DETERMINATION OF CKRYSOTILE ASBESTOS IN TALC BY X-RAY DIFFRACTION Author: Pasquale Brscese Analytical Section PC UT RPA 62130 Referenced Lab Notebook: 5075 Previous Research Report: None /C> "f ~ CL ~r,- -/ Submitted: P. Brscese Section Head: C ili $ ABSTRACT An x-ray diffraction technique for the determination of chrysotile asbestos in talc is described, Quantitative analysis is made by measuring the area under a selected diffraction peak using the step-scan procedure. The (002) chrysotile peak d = 7.3 A is ideal for this measurement; however, the talc (N.C. Regal Talc used in this study) contains Kaolinite (001-) line d = 7*18 A .as a contaminant which interferes with this chrysotile line. Therefore, the (00l+) line, d = 2.6k A0 , of chrysotile was used. To compensate for its weaker intensity, a longer exposure for each step was used. This was statistically calculated0to be 80 seconds. The method is estimated to have a lower limit of detection of 0.2# chrysotile in talc. iv TABLE OF CONTENTS ABSTRACT...... ............... ....................... iii LIST OF ILLUSTRATIONS................. ............ ,. v LIST OF TABLES........ .......... .................... v DIGEST OF REPORT...................... ,............. 1 EXPERIMENTAL DETAILS...... ........ . .... ...... 2 1. Instrumental Conditions....... 2 2. Estimation of Expected Intensities..... ... 2 * 3. Procedure.....................k U. Calibration Curve......... ..... ........... 1+ 5. Analytical Error Due to Counting Statistics 5 6 . Variation of Standard Deviation with Counting Time............ T 7. Lower Limit ofDetection ( L . L . D . . 9 RESULTS.............. 10 1. Reproducibility and Precision of the Instrument................ 2, Recovery Study.............. 10 .10 DISCUSSION.............. 11 CONCLUSION QND RECOMMENDATIONS......... -.,.......... 12 INDEX TERMS.......................................... 13 REFERENCES....... ik r ( C Y LIST OF ILLUSTRATIONS Figure 1 Working Curve: Intensity Net Counts in O.U Angle vs. Concentration, Weight % Chrysotile Figure 2 Variation of Standard Deviation With Counting Time LIST OF TABLES Table 1 Table 2 Standard Components1 Weights in Grams Results: Intensity-Net Counts in O.h0 Angle vs. Concentration Weight % Chrysotile Table 3 Analytical Error Due to Counting Statistics Table h Reproducibility and Precision of the Instrument Table 5 Recovery Study J C DIGEST OF REPORT Introduction The chaxacteristics of x-ray diffraction patterns provide a specific method for the identification of crystalline compounds. This technique can "be applied either qualitatively or quantitatively to the examination of solid materials. The allegation that commercial samples of talc contain asbestos minerals contaminants which could be hazardous to health when inhaled led to the development of this method, '* Major interest is focused on chrysotile asbestos, a fibrous variety of . serpentine, vhich shovs major diffraction peaks at d = 7.3 A and d = 3*6^ A while the amphibole group, another variety of asbestos, shovs a maximum at d = 8.1 A. (1 ,2 ) This report presents details for the quantitative analysis by x-ray diffraction of chrysotile asbestos in talc at the (00^) line corresponding to the major diffraction peak at d = 3.6^ A. r 2- - * EXPERIMENTAL DETAILS 1 . ' Instrumental Conditions Apparatus: Philips Electronics Instruments x-ray generator, type No. 12215/0, was used in combination with a high angle vertical goniometer, scintillation counter and step-scanner, - -GuK^ radiation, Nickel filtered, generated at 35 kv and 18 Ma. Slit system: divergence scatter receiving *Io 0.006 inch Io Signals from the detector were fed through a pulse height descriminator and the integrated counts per step printed out on a teletypewriter. The step-scanning arrangement permitted the measurement of small integrated areas of 0.01 per step. A total of 1+0 steps covering an angle of 0.1 2 theta from 2 1 .20 up to 2 1.60 was used for peak area, and an angle of 0.2 2 theta from 23.50 up to 23.70 and 26.15 up to 26.35 vas used .or background. ./ Ip every sample prior (to counting for quantitative analysis, a qualitative scan is necessary over the angle from 23 up to 27 2 theta to ensure thau the area considered for background is free from interferences, ; !}. , Counting time per step was 80 seconds and total counting time 80 x 10 = 3 ,E00 see"Uls for peak area a n d '3,200 seconds for background. (6 ) y Reagents*: J / North arolina Regal Talc from Charles Mathiew, Inc. Chrysotile Asbestos ?,4_l0 obtained from Whittaker, Olaik and Daniels, Inc. * Both materials were supplied through the help of the Skin Products Section. C. 2. Estimation of pcpected Intensities Talc, a natural hydrous magnesium silicate with the formula Mg S ^O^q (OH)-, crystallographically is monoclinic and triclinic in form. Geologically, the mineral occurs in rock masses and co-exists with! a large number of other hydrated magnesium mineral specie s~r C "J- Chrysotile, a naturally-fibrous mineral, is a hydrated silicate of magnesium which approximates in composition the formula H, Mg Si 0 , The structure is monoclinic, four molecules of H^Mg Si^O in nhe ^ unit cell. Each silicon atom is surrounded by four oxygen atoms arranged at the point of a tetrahedron. Together these groups form chains extending parallel to the vertical axis. The binding forces between these chains are weak, thus accounting for the fibrous Structure. It includes most of the silky amianthus of serpentine rocks and much of what is popularly called asbestos. (U) Qualitative examination by x-ray diffraction of N.C. Regal Talc showed mainly talc, with the following minor constituents: chlorite, kaolinite, phlogopite, dolomite and alpha quartz. No detectable quantities of asbestiform minerals, either the amphibole or serpentine group were seen, (2) , Of the above constituents, none absorbed Copper K, radiation strongly in relation to talc, this is known from "study of the appropriate chemical elements constituent to each compound. So, absolute counts versus concentration of chrysotile should give a straight line. The intensity of the (00l|) line of pure chrysotile d = 3.6^ A gave 5^0 counts/second net by step-scanning, (In terms of counts per second per percent ,his = 5.^0 c/e/%.) Calculation of mass absorption coefficients for Cu K radiation gave 32.0? for talc and 29.88 for ichrysotile, The following equation gives the c/s/$ expected in a mixture of talc and chrysotile. 5.h x 29.88 o/b /% = 3.2.07 5.03 ljp . x 100 - r Practically no corr ction is needed due to absorption in the mixture of talc and chrysotile. (3 v*5) The value obtained for the mass absorption coefficients are based on the formulas for talc, Mg Si,0 _(0H) , and chrysotile Mg Si 0 (OH), . (Card No. 19-770 fdr talc an*d9-bhh for chrysotile edited by the Joint Committee on Powder Diffraction Standards.)* C * Joint Cormilitee on JCPDS Powder Diffraction Standards l601 Park Dane, Swarthmore, Pennsylvania .C ^ 19081 l c C C 3. Procedure -b No special sample preparation was necessary for the talc. North Carolina Regal talc is already finely-ground to pass a 325 jnesh sieve, 1+1+ microns opening, as received. The chrysotile asbestos obtained from Whittaker, Clark & Daniels, Inc., #1+10 , was partially ground and needed further grinding to diminish the particle size to an average of 50 microns. This was accomplished by 2 hours grinding in a Waring Blender.* The ground fibers were checked by microscope for size, * The blending assembly can be obtained from Waring Products Service Center, New Hartford, Connecticut 0605T> Model No. J>0l8, An exactly-known weight of chrysotile was added to the talc. The mixture, tightly closed in a weighing bottle, was placed in another jar and insulated with tape in the jar to avoid breakage. This jar was placed in a mixer/mill* and each sample mixed for 1 hour with the help of two plastic balls. * Spex Model 1810, Spex Industries, Metuchen, New Jersey. Each sample, after be .:g properly mixed, was loaded in a flat aluminum x-ray sample.holder. Care was taken to ensure proper loading of the powder/ To minimize orientation effects and to standardize the procedure for each sample, the;following three steps were found necessary: / L 1. Load the sample holder and press the powder with a spatula. 2. Remoye the excess with a Gillette razor blade. 3- Make the surface flat and smooth by pressing with a g'-ourd glass plate. Finally, place the sample in the x-ray instrument and take counts over the peak and background areas. ( C. 1+. .-C-a--l-i--b--r-a--t-i--o-n----Cjurve . *c Chrysotile can be detected with a high degree of assurance by a qualitative x-ray scan when present at approximately 5% and higher. Consequently, a calibration curve covering the range from 1 to 5$ only was necessary. Samples used for calibration are listed in Table._1.___. ----- c C c Table 1 Standard Components*^Weights in Grams Talc 2.1*75 2.1*50 2.1*25 2.1+00 2.375 Chrysotile 0.025 0.050 0.075 0.100 0.125 Total 2.500 2.500 2.500 2.500 2.500 ' ! Chrysotile 1.0 2.0 3.0 1+.0 5.0 Results obtained by x-ray analysis are listed, in Table 2 and plotted in Figure 1. Table 2 Results; Intensity Net Counts in 0.1+ Angle vs, Concentration in Weight % Chrysotile Concentration Weight % Chrysotile Intensity Net Counts 0.1+ Angle 1.0 t 2.0 3.0 1+.0 ,f 1 5.0 f 26.1*00 39.100 61.870 86.1*30 102.550 Net Counts = Total Counts (Peak Area - Background Area) Using the method of least squares, the following equation was found for the relationship between intensity and concentration. y = intensity (net counts) x = concentration in wt. % chrysotile t. , Equation of the line; y = 3381 + 19-9&3 x. Analytical Error Due to Counting Statistics (5) A series of measurements for 1, 2, 3, 1+ and 5%'chrysotile in talc gave the following counts. Table 3, columns 2 and 3.. !t ' 1 c cv c -T- The standard deviation (G) in percent of a measurement involving a given number of counts at peak area Np and a given number of counts 100at background area Nb is (*) = tfpjEIi Np - Nb In Table 3, 2& is shown as counting error and in terms of % chrysotile, columns 1+ and 5 . / Table 3 Analytical Error Due to Counting Statistics Concentration Np Counting Error'26 Nb Error 2(* % Chrysotile 1% 353,080 326,1+1+0 6 .2# 0.062# 2% 360,7ko 321,61+0 h.2% 0.08k% 3% 386,390 32l+,520 2.7% 0.076% hi 1*29,190 31+2,760 2 .0% 0.030% 5% 1*33,390 330,81+0 1.7% 0.085$ 6. Variation of Standard Deviation With Counting Time (5 ,6) A series of measurements of a sample containing 1% chrysotile in talc gave a total count 353,080 for the peak area and 326,1+1+0 for the background area. (1+0 steps, 80 seconds per step). Taking the same number of steps, i.e.s 1+0, and different counting time, i.e., 5 , 1 0 , 20, 1+0. 60, 80, 100 and 200 seconds per step, the following equations are applicable. me x 353,080 = Counts for peak area = Np T p t ^ 9^ p iTime x ,, 3 for background . ^ where; G(%) = 100 3 NP * ^ Np - Nb From the data obtained, a curve is constructed in Figure 2 showing the standard deviation as a function of counting time. No great advantage occurs by increasing the counting time above 80 seconds. 0*5 (*) ero o 't- -9- J. Lower Limit of Detection (L.L.D.) (5,6) The lower limit of detection is normally defined as that concen tration which gives a count rate equivalent to a background reading plus twice the standard deviation of the background. This assumption will be correct in 95# of cases studied (95# confidence limit). where: Fb = 326,H o net counts of background ffib = 571*35 counts for 1 (6 ) 2jfib - 11*12.70 counts for 2 (6) Equation of the line y = 3381 + 19,967 x Let y = 0 9 x = -0.17# Let y = ll*i3 counts = 2(Pabove background x = -0.11# L.L.D. = A * = x at y = 11*^3 - x at y = 0 0.06# As a figure of merit, it is better to multiply the L.L.D. by 3, where 3 is a factor which corrects.for instrumental drift. Therefore, L.L.D. = + 0.18# chrysotile. C. f C c - IQ - RESULTS J 1. Reproducibility and Precision of the Instrument The reproducibility of the x-ray instrument was checked by daily analyses on a standard for 6 consecutive days. The. standard used contained 5% chrysotile. Table 1+ Reproducibility and Precision of -Me Instrument Standard: 5# Chrysotile in Talc Day Intensity: Net Counts 0.1+ -Angle # Chrysotile 1 102,550 2 102,230 3 103,979 1+ 100,039 5 97,261+ 6 101,551+ 5.13/? 5.12/? 5-21? 5. Oli? k. 5.08i? Av. = 5-07% SD = + 0.12 RSD = 2.3% 2. Recovery Study A sample of M6670 #1*50 finished product Cashmere Bouquet Talc was checked for chrysotile with the present method and gave zero % chrysoti]e. Chrysotile was added to it for a recovery study. The results are listed in Table 5* Table 5 Recovery Study ( Total Weight in Grams % Chrysotile % Chrysotile ' of Talc and Chrysotile Added Found % Recovery 2.5 0.2 0,33 165 2.5 0.5 0.6l 122 2.5 1.0 0.93 93 2.5 2.0 1.73 66 2.5 5.0 1+.9 98 The very high recovery at the 0.2# level and the more acceptable results at the 0.5# level, limit the technique to the order of Q.5#* - 11 - DISCUSSION The method presented can be applied satisfactorily to detect chrysotile asbestos in talc. It was developed especially for the evaluation of chrysotile asbestos. In principle, however, it can be applied to any other type of asbestos subject to the limitation of producing suitable calibrations. The lower lir T.t of detection was calculated as 0.2%. Further improvement of the detection limit for this method will require the use of a more powerful x-ray tube, generator and" improved revolution provided by the use of a crystal monocromator It was an unfortunate case that talc invariably contains, among other contaminants, kaolinite, making it difficult to use the more intense line (002) of chrysotile due to the proximity of kaolinite, 7.18 A, and chrysotile, 7*3 A lines. An early attempt to use this line after thermally destroying kaolinite at 500C proved that along with kaolinite some chrysotile was also destroyed. (3 ) Carrying the method furthe. to use the 002 line can be very rewarding for the sensitivity that can be attained, calculated to be b6% better. However, this is not without sacrificing a lot of time since the parameters involved are many. i if By looking at the less intense chrysotile line (00U), free of interference, and by selecting the proper parameters, favorable results were obtained. t7 Tetri time required for the analysis of a single sample is estimated at 3-1/2 hours. ! / i c. c - 12 * CONCLUSION M D RECOMMENDATIONS X-ray diffraction offers.a specific, accurate and precise method for the determination of chrysotile asbestos in talc at 0.5# and above. * C ( < ( 13 * INDEX TERMS , X-ray Diffraction 2. Chrysotile Asbestos 3. Talc o ( < ~ Ik * REFERENCES 1 . J. V. Cradle, Am. Ind. Hygiene Assoc. Journal, p. 293, May-June (1966). 2. Analytical Data on Reference Clay material. "American Petroleum Institute Project 1+9 Clay Material Standard" , Columbia University New York, July 1950. 3. Klug and Alexander, "X-ray Diffraction Procedure" John Wiley 8s.Sons, Inc., pp. 1+08-1+09, Appendix V, p, 677. U, Danas, "Textbook of Mineralogy", 1+th Edition by W. E. Ford, John Wiley & Son<sP, Inc., 19I+2. 5 . R. H. Jenkins and B. De Vries, Worked Examples in X-ray Spectrometry, Philips Technical Library Springer-Verlap, New York, Inc., 1970. 6 . P. Briscese Notes: Practical Applications "X-ray Powder Diffractometry". State University of New York at Albany. C