Document 8RB2jrRjp4K1G3n7kLRKd1nXe

FILE NAME: CTFA (CTFA) DATE: 1974 June 21 DOC#: CTFA021 DOCUMENT DESCRIPTION: Meeting Minutes-CTFA Task Force on Methodology for the Detection of Asbestos in Talc ' > S Minute of the meeting of the CTFA Task Pore on M o f Asbestos In ................. , Present we rethefoilowlngj fe#i F . Roben Rolle. Task Forc Chalrman Isn Stewart D. Harria EESigli^^ ' Johnton b Jo McCxosfl A Cypru.Indu.trLI Mineral V/alterLuckewicz ^ r j0 0 $ M iz George Sandland " - |j|pg|p^ Brietoi Myera 1. Mr. David Hamer discussed the moat recent version of the FDA ,, , . , microscope method for the d e te r m in a tio n o f a hetoe fibers in talc. The only differ ence between this method and the earlier method is that the area of the sample to be scanned is reduced, thereby reducing the time of analysis, The method is still unacceptable, however, for all the reasons given in the December 10, 1973 CTFA report, "Report of CTFA Talc Sub-committee on Method to Detect Chrysotile and TremoUte in T alc". 2. The R ose1 dye procedure for the detection of chrysotile In talc has been evaluated by Dr. C. S . Thompson, and he finds it non-specific. For example, the serpentine minerals antigoritc and lUardlte also show adsorption of the dye. He further pointed out that the method is very time consuming. Dr. T, Baak (Cyprus Ind. Minerals) in an earlier communication reported that the mineral palygorskite would *V- in a manner sim ilar to chrysotile by this method. Mr. W. Luckewicz reported that the particle size of the tation of chrysotile chrysotile would by this analysis. have a dramatic effect on any attempted quanti mm. 3. The infraredmethod proposed by Mr. W. Luckewicz and evaiuated by Bristol Myers has been shown to be specific for the detection of tremoiite in talc. The level | of detectability is about 1% by weight. 4. The "cookbook" transmission electron microscope procedure of Pfizer for the detection of chrysotile in talc was found acceptable, however, Mr. Ian Stewart wpu|d :\v^ ii prefer to quantify by area count rather than "eyeballing" against a spiked standard. 5. The "cookbook" Differential Thermal Analysis (DTA) procedure of Johnson &Johns and Avcn, for the detection of serpentine in talc, was accepted by the committee. The minimum level of detection is 0.5-1% by weight. 6. The "cookbook" x-ray fluorescence procedure lor the determination of tremoiite in talc, followed by dispersion staining In the event of a positive reading, was accepted by the committee. ^^tSSRSI ?. The "cookbook" x-ray dlffra tion method for the detection of amphibole minerals In talc by Cyprus and Pfizer was accepted by the committee. The lower limit of detection was set .at 0.2-0.5% oy weight. , "Detection and Determination of Chrysctiie in Talc USP", J. of CRM C-T alc-Micro-003497 HHp CRMC-Talc-Micro-003498 lllKlftll This method permits the detection of chrysotiie and other serpentine minerals in pharmaceutical grade talc containing less than 10% by weight chlorite. The minimum level of detection is 0.5 - 1% by weight of chrysotiie asbestos. the instrumental parameters must be determined for the particular differential thermal analyzer which is employed, with regard to geometry of the sample holder, sensitivity of the differential thermocouple, etc., such that 0.5 - 1% by weight chrysotiie may be easily detected, The successful development of the OTA method is, based on the preparation of homogeneous chrysotiL standard samples. Standards containing 0.5, 1, 3, and 5% by weight chrysotiie in talc are prepared as foilLows : * a. Five gm. of the standard talc is slurried in about 100 ml. of ethanol in a Waring Blender. b . The appropriate weight of chrysotiie asbestos of at least 95% purity is then added to the talc slurry, and the mixture is blended for 5 minutes at low speed. c. The solution is washed into a beaker withethanol, and the solvent is evaporated, on a steam bath. d. The resulting caked sample is broken and mixed In a plastic vial by shaking for 5 minutes in a mixer such as the Spex Mixer/Mill. a. The homogeneity of the chrysotiie-talc standards should be verified by optical or electron microscopy. 4. The experimental conditions, for example, for the Stone DTA unit (Models LA-XYH and RC-202C) are as follows: High temperature powder sample holder of nickel or stainless steel construction (Model SH-3BE2) with exposed-loop differential thermocouple (Platinel II) C R M C -Talc-M icro -003499 ?Ar*Vvrv : --- -- Temperature range: -2- . fe-jtg: ambient to 1000C. Reference thermocouple: Platinel II or < Sample: 130-140 mg. talc, using a loose packing technique. Reference material: alumina, ground to pass a 325-mesh sieve (maximum particle sise of 44 microns) Inert dynamic atmosphere: helium or nitrogen at 0.05 SCFH Heating rate: .10C./minute Sensitivity: 40 jjvolts full Furnace: LTF, water cooled to 1200C The purpose of the inert dynamic atmosphere is to prevent oxidative reactions and to sweep out gaseous mineral de composition products. The Stone powder sample holder yields maximum sensitivity by permitting direct contact of thermo couple and sample. True dynamic gas flow through the sample *' is also attained. It may be possible to use a more rapid heating rate with some DTA instruments, if it can be ascer tained that constant thermal equilibrium exists between sample holder and furnace. Reproducibility of the method is based on standardizing the experimental conditions. Initially, a thermogram of the blank standard sample is run in order to determine the thermal profile of the talc. A thermogram is run on chrysotile asbestos by diluting the material approximately 1:4 in fine alumina. The thermal transitions involve a dehydroxylation endotherm at about 650C and a recrystallization exotherm at about 820C. These two peaks establish the presence of serpentine mineral. 7. The 5, 3, 1, and 0.5% chrysotile in talc standards are then analyzed. Both thermal transitions of the chrysotile in the 1% standard should be easily detectable. If not, the exper imental conditions muse be altered to improve detectability. 8. formally, pharmaceutical grade talcs will not require additional grinding for DTA. The analysis of talc rock or the presence of lumps or gritty material will, however, necessitate grinding the sample to pass a 325-mesh sieve. C RM C -T alc-Micro-003500 ; il conditions ie as follows! Heating rate: 30 C. minute CRMC-Talc-Micro-003501 DETECTION OF AMPHIBOLE IN This continuous scanning X-__# ------- . . detect the presence of amphibole ' * ` - -- a lower limit of based upon ana: .. , ......... -.....I M H 1 n ......... The procedure consists of slow-scanning*under determined conditions, a compressed pellet of the sj in the 11,0-10.029 (8.85-8.048', _------ r-------- -- an amphibole peak. 1 - Standard Preparation Optimal instrument conditions must first be determined -- with the use of tremolite standards - 1.0%, C.5%, 0.25%, tremolite by weight prepared in a standard talc which is free f1 of interfering peaks in the 11.0-10.029 region. The tremolite standards are prepared in the following manner: a. Weigh out appropriate amounts of standard talc and tremolite of at least 95% purity, both of which have been ground to pass a 325-mesh sieve. Transfer to a Waring Blender (or equivalent). Add 100 ml. of ethanol to the blender and blend at low speed for 5 minutes. C R M C -T a lc -M ic ro -0 03 5 0 2 Temperature range: ambient to 1000C. - Reference thermocouple: Platinel II or Chromel/. Sample: 130-140 mg. talc, using a loose, conaia Reference material: alumina, ground to pass a 325-mesh sieve (maximum particle size of 44 microns) ' Inert dynamic atmosphere; helium or nitrogen at 0*05 SCFH . Heating rate; 10C./minute U v l t M t , , 40 full . c l . Furnace: LTF, water cooled to 1200C The purpose of the inert dynamic atmosphere is to prevent oxidative reactions and to sweep out gaseous mineral de composition products. The Stone powder sample holder yields maximum sensitivity by permitting direct contact of thermo couple and sample. True dynamic gas flow through the sample is also attained. It may be possible to use a more rapid heating rate with some DTA instruments, if it can be ascer tained that constant thermal equilibrium exists between sample holder and furnace. Reproducibility of the method is based on standardizing the experimental conditions. 5. Initially, a thermogram of the blank standard sample is run in order to determine the thermal profile of the tdlc* A thermogram is run on chrysotile asbestos by diluting the material approximately 1:4 in fine alumina. The thermal transitions involve a dehydroxylation endotherm at about 650c and a recrystallization exotherm at about 820C. These two peaks establish the presence of serpentine mineral. 7. The 5, 3, 1, and 0.5% chrysotile in talc standards are then analyzed. Both thermal transitions of the chrysotile in the 1% standard should be easily detectable. If not, the expermental conditions must be altered to improve detectability. 8. Normally, pharmaceutical grade talcs will not require additional grinding for DTA. The analysis of talc rock or the presence of lumps or gritty material will, however, necessitate grinding the sample to pass a 325-mesh sieve. C R M C -T a lc -M ic ro -0 03 5 0 3 fm M m m i5i'* t7H. vam H ^ w B B is % m ,'f.J I - 1 M M $ 0 WtfV 4s9M!&mgra r;;',/-v*;y iL ^ -*>r13. 1;r-~ES 3a . / :,,v- - - V v . ; | M w .H i ; 1 -<>'.?,l i a L- . ' i ' J .. ;^,i f e ; | ^ # ; ; - . > : :r : ' v'.:*v* '&::: ' ,3;? fefatesfsaMKaifi gP ^S H R liS iii erangf 1 19i mmmm 7k.. 1Im%?: f^2-i.^ Atmosphere: static air Heating J*Ifp? r,i,*WT.?A W I * '* > ./iVvifr i.VjJ^rj.JCTv mmm iM mf '" W'.i 118 S v/`'*';W;V'>-s ?y ! ^ ig Mfe! r.i?>;-'f?4?:;:"^ '.V. 'jr^'TUiS^.'^v. m m sm m m m .'*. -, V* - -' ' * Il I--, -..:TM $*.< X'.jJi'!'i '[>^.'vl^-^kJiuw^!X'i yfrrr^? 7 y ^ -U^ ^ , 1ij.f ,',*.J* 'il &M p& s *! H IM t ' '` -1,*.y,ijttk J lTjVi.,,$/# i2i ! \v ' V*r,."iV-KT-I.Si r'u*~Urt*k*d* *'' lA:'.VrV'l*a fK43>. pVA-^i-f; . . J*!,"IrV i' '.W ^j Mixer/Mill or equivalent to . resulting fro m the evaporat: ... r t . ' f j e. T h e homogeneous standard is p r e ssed ' ' ' " backed with boric acid. 2 - ^ ja into a .m :-HU3SSSK .--v....>.`.i?{&**%!&! 1%" p ellet J to the die-holder and evenly distributed on a polished; scratch-free die. 4 gram of b o r i c acid is then evenly on the talc layer. The mixture is p r e s s e d into a pellet u n der a pressure of 24,000 lb. (calculated o n a 3M ram) for 5-10 minutes. The resulting pellet must have a talc face which is free of flaws; if not the pellet m u s t b e discarded. (This requirement is critical since excessive surface scatter ill cause excessively high background counts.) Three acceptable pellets are prepared from each standard. 2 - Sample Preparation Three pellets are prepared from each sample in the manner described for the standard pellets (l.Step e.). A CRMC-T alc-Micro-003505 in the 11.O-1O.O20 (8.85-8.04X) region of the eel presence of the latter will eliminate use of this for the sample. are optimized on the IX StandardLower standards are then analyzed under the to determine the lower level of detection, in obtaining maximum instrument sensitivity are a slow diffrac tometer speed combined with a compatible recorder speed and high attenuation with a statistically acceptable time constant on the ratemeter . Instrumental conditions employed for the Siemens Diffractometer (Model No. M386-X-A4), and counter and Recorder Unit (Type T) ' are: . Radiation: Gu with % filter at 40 KV and 24 Ma Divergence slit: 1 Receiving slit: 0.2 mm Goniometer speed: 1/1020/minute Recorder speed: 300 mm/hr .... .. Attenuation 8 4 x 02 impulses/second Statistical Time constant, T(s> 10 error of 1.1% under these ' conditionivv-a Rise- Time ^ 0.18 ttlbliiii"m 20 .. C R M C -Talc-M icro -003506 CRMC-T alc-Micro-003507 "jfSh t From: T . H . J a c k s o n T P Ti Subject: w i n t h r o p L a b o Your Letter 6/17/74 - . . rr.... .' - The paper "Detection of Chryaoti one Harry Rose of Eli Li" " detecting chrysotiie by inspection. The c adsorb the dye in O u r 'e x p e r t in detei . Jim Leineweber of Research learn that chrysotiie from different differently-- and so do talc from diff article describes work with carefully chrysotiie and pure talcs. (J)L IpH1if :-~\:kx'.ii-1 We would not regard the proposed technique as reliable as a standard test for all types of talc or chrysotiie. Detection of chrysotiie by X - r a y d e f r a c t i o n would be more reliable, and is e a s i e r to p e r f o r m if y o u h a v e the equipment. Low levels of chrysotiie in talc can be measured only microscopically-- and an electron microscope is necessary. I f Mr. Ellis wants more detailed information or amplification of this brief comment, I suggest you have him call Leineweber, (303) 770-1000, Ext. 83-553. T. M. Jackson TMJ ccr CRMC-Talc-Micro-003509