Document VJ56gQ5bD2813NYrJEGVO1XbN

j-ixJj. A u c i x u a a r u INSERTION OF "COSMETIC TALC" STANDARD INTO CTFA STANDARDS Attached are: 1. New CTFA Specification for "Cosmetic Talc" 2. Four new Methods (relating to "Cosmetic Talc") The new CTFA Specification for cosmetic grade talc replaces the Specification for "Talc" issued 5-30-71. In your Spe cifications binder, remove the Specification entitled "Talc" (1971 revision) and replace it with the attached Specifica tion entitled "Cosmetic Talc" So that your index will re main accurate, you should be sure to file this new Specifi cation under the "T's" (rather than the "C!s") where the old Specification fell. The four new Methods are additions to Methods already in your Methods binder They are: E 32-1; J 4-1; J 5-1; and J 6-1 Remove nothing from your Methods binder. Simply insert the four new Methods in the appropriate sections of your Methods binder. Previously issued Methods and the Spectrum are still applicable Do not remove them from your set of CTFA Standards. CTFA Adoptad ama: TALC COSMETIC TALC TALC COSME Issued: 5 Revised: 3- 5- 10 DEFINITION: Cosmetic Talc is an essentially white, odorless, fine powder, ground from naturally occurring rock It consists typically of 90% hydrated magnesium silicate, having the ideal formula Mg6[Si8O 20](O with the remainder consisting of naturally associated minerals such as calcite, chlorite, dolomite, kaolin and rr nesite, and containing no detectable fibrous, asbestos minerals. TEST C o l o r ..................................................................................................................... O d o r ................................................. Identification ................................. Slip .......................... ............... ............. Lustre .................... .............................................................. W ater-Soluble Iron .......................................................... Screen T e s t ................................... Water Soluble Substances ........................ Acid Soluble S u b s ta n c e s .................................. Loss of Ignition ............................. Arsenic (as As) ....................... .... Lead (as Pb) ................................. Fibrous A m p h ib o le ....................... (Asbestiform Tremoiite et al) Free Crystalline S ilica ................... (Quartz) SPECIFICATION As specified by the buyer and showing no change after heating As specified by the buyer Positive: 1. Close match to CTFA Spectrum-~IR with no indication of foreign materials OR 2, (Alternate) Close match to X-ray Powder Diffraction File No. 19-770, published by ASTM, showing the most intense reflections at d values about 9.35, 1.53 and 4.59 As specified by the buyer Do. Passes test 100% through 100 mesh 98% minimum through 200 mesh Finer grades: as specified by the buyer 0.1% maximum As specified by the buyer 6.0% maximum 5.0% maximum 3 ppm maximum 20 ppm maximum None detected METHOD Heat 1 to 2 g at 200C for 5 minutes CTFA G 3-1 ASTM D 934-74 USPXiX, page 487 CTFA C 6-1 USP XIX, page 487 See test for " Reaction an Soluble Substances" CTFA E 32-1 USP XIX, page 487 CTFA F 1-1, Parts l-A an< CTFA F 2-1, Parts l-A am CTFA J 4-1 As specified by the buyer * a it -a * CTFA J 5-1 (DTA) Alternate: CTFA J 6-1 (X-i Copyright 1976 The Cosmetic, Toiletry and Fragrance Association, Inc. | f I l|' CTFA Me ACiD SO LUBLE SUBSTANCES IN TALC w P rin c ip le =. ; V / v . : ; ' :- A sample of talc is mixed with diluted hydrochloric acid and the insoluble portion is removed by centrif filtration. The filtrate is sutfated, evaporated to dryness and ignited. The acid soluble matter is determine! cally as the sulfate. r. ; Apparatus 1 . Controlled temperature water bath . ; *..:v >:v. -T 2. Beaker, Griffin, 100 mi -.../.T- " P' 3. Volumetric flask, 50 ml V ; V . ' * 4. Centrifuge ' ;;> S `V. -v'; . - ' A ' . , , ; ' 5. Cantrigugetubes(2) ,5 0 ml - .. 8. Graduated Cylinder, 50 ml . / ' 7. Sintered glass funnel, ultra fine porosity, 80 mi (0.9 to 1.4 /m) Coming #36080-UF or equivalent 8. Vacuum flask, 125 ml : y- \ - 9. Pipette, 1 0 ml -, .! \. . 10. Platinum or Vycor evaporating dish or equivalent . . . A A A : T-. A v A Reagents 1. Hydrochloric Acid, diluted, 10% v/v 2. Sulfuric Acid, diluted, 10% v/v Procedure \ .. ; . ' ; ' : ' /'. ' Weigh 2 g ( 0.001 g) of sample into a 100 ml beaker, add 40 ml diluted hydrochloric acid, and place in v 55 (2.5)C , with occasional stirring for 30 minutes. Immediately remove beaker from bath and pourco> 50 ml centrifuge tube, rinsing beaker and stiring bar with 2 to 3 ml of distilled water. Centrifuge at 5000 minutes (Note 1). Filter supernatant through ultra fine porosity sintered glass funnel into vacuum flask, using 2 to 3 ml of disti rinse the centrifuge tube and funnel, and using care to avoid dislodging the packed talc at the bottom Filtrate must be clear (Note 1). Pour filtrate into 50 ml volumetric flask, rinsing with 3 to 5 ml distilled wat volume with distilled water. ..A' , - Pipette 25 ml of adjusted filtrate into tared, ignited evaporating dish. Add 2 ml of diluted sulfuric acid and < dryness. --i- Ignite at 800 ( 25C) for 1 hour. Cool and weigh. / C alculation % Acid Soluble Substances Weight of Residue in g x 200 Weight of Sample in g Not 1 . Examine the centrifuged sample carefully to assure good clarity before proceeding with filtration. I' detected, centrifuge the sample for an additional 15 to 30 minutes as necessary. * * * * ASBESTIFORM AMPHIBOLE MINERALS IN COSMETIC TALI Part 1: X-ray Diffraction Method Part II: Optical Microscopy and Dispersion-Staining Method Introduction ; / V '--'-1 The method which has been adopted for the detection of amphibole minerals in cosmetic talc is t accepted method of x-ray diffraction. Methods which appear in the literature for the detection of fibrou such as, transmission electron microscopy with selected area diffraction1 and electron microprobe been considered since they are capable of a lower level of detection than by x-ray diffraction. Howev* not been adopted since they suffer from the drawbacks, that the amount o material under examini small (less than a microgram) and the time for analysis, expertise required, and expense o? equipme them as routine methods. .,. . v. : V- . : :?r. ; ; : *v' v. '?v' The methodology presented is the most practical available, based on current technology. The use o f ' Electron Microscopy with Selected Area Electron Diffraction offers greater sensitivity, but is not presi is unsuitable for normal quality control application. ; v v ;- A V' Enrichment or concentration techniques using flotation cells have been tried-as a means of improving level; however, all efforts so far have been unsuccessful, ;. P rin c ip le The x-ray diffraction method is based upon the principle that when a crystalline material is placet beam, a portion of the x-rays are diffracted by each set of atomic planes within the crystal. The d strike a scintillation counter as the sample is scanned through a prescribed angle with the resulting of peaks corresponding to each interplanar distance (d). A peak with d value in the range of 8.04 to sample talc is strong evidence for the presence of amphibole In that talc. The level of detection of i this method is 0.5% and above. The variability of-detection is caused by such factors as age and m2 x-ray diffractometers, sample homogeneity, specific amphibole mineral present, morphology of amph size, preferred orientation, etc. For these reasons the level of detection should be reported for levels since below this level the data has been found to be not reproducible. If a statistically significant pei intensity equal to or greater than that obtained for the 0.5% standard in the d range for amphibole, des then the sample must be put through the following confirming scheme: X-ray Diffractometry ( + ) ---^ Optical Microscopy -- ( - ) -> Stop (Ampi ' (Acid Leach) , : and >, *.'V . < -) Dispersion-Staining Color Stop (Amphibole absent) <+) Fibrous Morphology ---<-----)--} Stop (Asbestiform Ampi (+) / ...V - ' ; ; Stop (Asbestiform Amphibole present) issued: 1 Part I: Amphibole Minerals by X-ray Diffractometry Apparatus , 1. X-ray diffractometer, employing nickel-filtered copper K-alpha radiation, horizontal or vertical gonior with variable scan speed capability, suitable talc pellet sample holder, variable speed recorder, elect , , 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) f .V ; ; y'- *V. ' . ' 4. Waring B lend er/or equivalent blender ; . : ;y ';y y 5. Spex Mixer/Mill/ or equivalent mechanical mixer ..6; Sieve, 325-mesh /, v X - '!:v :7 ' . . '7 > y y y / y : y y 1. Optical microscope (Mote 2) ' ' ' ' y y ^ y / y y y y v ^ y '.;.y . ' - '7 .'V 8. VA*pelletpress - \ : 7... : ;y . y - \ y- ....- . y . y y Reagents >' . - s'. ., 1. Standard talc sample, containing no detectable amphibole minerals y . ; -2. Standard tremolite sample, at least 80% pure : > tion, Inc., 1133 Fifteenth Street, N.W., Washington, D.C. 20005 'y 3 / Denatured ethanol >;' 7 ; " y 7 / V ^ y ' / :/ ;: 4..:Boric acid.. 7 ;y V " "S / it.- 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 timer/scaler is required on the electronic panel of the x-ray diffractometer. In orderfor a peak to be V'-.' v i Determine the region of the scan in question: in the Figure 1 scan, a peak appears to be present in tt 10.60 28 region. Slow scan with cumulative pulse counting through the peak region three separate times and average t . of counts. ; , ' 4.. y . iW :.-A \ Determine a background count by scanning a region equal to V2 of the 26 region covered by the peak, ir time used for the peak. Count each background region three times. Then average each region and a averages to obtain the background count (N).: < I r-;y . :, V '# - :V Example: In Figure 1. Ragion (2 6} P e a k . . ........ ............................ 10.40 to 10.60 Background Region A . . . . . . . . . . . . . . 10.30 to 10.40 ; - '.Region'S yl- 10.80to 10-.70 Time (sec.) 120 60 '6 0 ' CX i y j 'v. B a c k g r o u ' . y :; -Peak J\*. ; : { Region A , 10.40to 10.60*28 -10.30 to 1Q.4028 = time secs, counts / time secs, counts nd ;" - ' Region B : 10.60to 10.70 28 time secs, counts :? 120 120 ; 120 Average 60,332 ' 59,870 60,105 80,102 ' :- ? ;y '6d ^ ' 8 , 7 8 4 80 28,943 0 ' 28,634 28,787 ' 60 - 28,506 60 28,368 80 28,204 28,359 : .N =s 28,787 + 28,359 * 57,146 : .<o' = V57.146 ~ 239 r 3a - 717 ' \ ;;yy N -F 3a - 57,146 + 717 - 57,863 ... therefore, the "suspect" peak is statistically present in the scan. r r ; V-; Standard Preparation ,' y .;';-.. , V -r-.- ... ; 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 V.;, which is free of interfering peaks in the 11.0 to 1O.O2-0region. Weigh out appropriate amounts of standard talc and tremolite both of which have been ground to pass i sieve. Transfer to a Waring Blendor,* Add 100 ml of ethanol to the blender and blend at low speed for 5 rr Carefully transfer the contents of the blender, with repeated ethanol washings, into a large beaker. Ev ethanol on a steam bath. / v >' -^ -i jA -v:v ^-' Shake the sample in a plastic vial for 5 minutes on aS pex Mixer/Mill* to remove dumps and caked samj from the evaporation of ethanol. `i*, Determine by microscopy the homogeneity of the prepared standard previous to the x-ray diffraction A- Press the homogeneous standard into a 1 ^ " pellet with a backing of boric add. Transfer 2 ( 0 .2 ) g of the die-holder and evenly distribute on a polished, scratch-free die. Distribute 4 ( 0.2) g of boric acid et a pressure of 15,000 to 24,000 lb calculated on a 3" ram has been found to produce suitable pellets). T pellets from each standard. -.>r - . . * ' * - .7 - ' '? < ic: v ' ' .-V ' f - ' * ' ' Ki> ' ' T. '5" .V. . ; ; ;-. V; x- ?.' .. v! v v f '*CK. ' .. ~ ./' v . ./ i f ., . turf's. Registered Trademark Sample Preparation Prepare two pellets from each sample in the manner described for the standard pellets. Make a qualitative from 4 to 50 28 on one of these pellets to ascertain the presence of amphibole above the 2% level or the pres of mineral impurities having interfering peaks in the 11.0 to 10.0 2 6(8.85 to 8.04) region of the scan. The pres of such interference will eliminate use of the x-ray diffraction method for the sample, and one will have to prc directly to the microscopical procedure. Instrum entation 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 time constant on the ratemeter. Under appropriate instrumental conditions the peak obtained for the 0.5% standard should Typical instrumental conditions employed for the Siemens Diffractometer (Model No. M386-X-A4), and Co and Recorder Unit (Type T) are: . Radiation: Divergence slit: Goniometer speed: Recorder speed: v v Attenuation: i v . - T i m e constant: Cu with Kbfilter at 40KV and 24 ma 1 Receiving slit: 0.2 mm 1/io 2 # m in u te 300 mm/hour 1 x 103 impulses/second .' / T (s) = 4 ; - ..kk.*. k 4 k . '> . Statistical error of 1.1% under these conditions T ; > Rise T rim - 0.18 ' . ' A;. ;' . V. :V Attenuator = '` " ..... /.' . . xf v :T i t 20 . . .* ' ' * ' , 1. : st- h p ' - - ............ . : v.; k k k -k k ,.: V k : ; / -- - ;. .J ; ; \ - v \ .. . w -* ... *: .** 'v . * .v: -V -i . .... m ? . vr f;.SA vi;,iv:'SiV ' -'-fyf'CT>y| :ii.; . . /'ji . , > k r ... ` r. 4/ V.':..- .V/V..V., ;t -v' T/K'- 2 `. ey. '.v:..- ; V' ` >v\. - ` .V* 4 1-. ..." r i.- A;,. '* r.>-- " 'V ; , v:. 5 V ,: / . *? : 'S . ` - . ... .; : ; - iK \ * ;- ' ,;a . ;vk;4 4 - 'j ' ; ^ r :> rv .k v -'kT: ' -v. -v-'.-./v -, ^ . ,, :. . . v .. :: k v..: V'-; -' k-k ... .. ^ , ' . ; ; .. >:y -a - - , " : -v`, i . .k . ' ../ v- , ' - v 1. .. " :j" ' 'I : " ; , * : v7 . ... , .. ^ <.iV V v,1' .-r. - ' ' : ' <;. ' .. '.t ' OTFA Me ' ;V ';_ . '. ^ ,, -7; i- ?? 7-p: -v . ^ ; ! * r-;; > ^ :- ' * M * IQjO 10J t0.4 10 10 11*0 * It'* ';* ' [:'rV ? y . V :v' 1 V''VTs' Figure Z- ;'.S .. : *.v ' ' *. * .* ' ' . i:. V *. *1- , : . . ' /. *'** v : > '.v > \. r *.. ;* s *1v 'f *. * ;i* ,,V.*' -/- . * ; v /'.* ' ' / ; * ' ' i/.l'; , *' V . ' >:VS ` . >;! v ..w- i *! ' ' : , v ` \ /- ". ; . ; . X-Ray Diffraction Scans . ' .V .. v -c r- `.' s'' ' ' . ' ? ; ; =: ' C : '..{[/ --J,.*..*' ' * S ; ' ^' v A r" ' ' v >: :/v . \r':, ;>* ^ ?.; .. , , ; A'- y - v iC : Place the standard or sample pellet in a suitable holder and slowly scan between 11.0 and 1O.O20. The pellet 90 with respect to its original position in the goniometer and rescan between 1TO and 10.O20 orientation may affect peak intensity. The presence of a reproducible peak (or peaks) is due to the \ amphibole mineral (or minerals); the absence of peaks in this region indicates the absence of amph sample, within the limit of detection of this technique. W^ Report results as "None detected" or as "Detected at approximately X% level," where "X" equals the lev CTFA Method Issued: Part 11: Asbestiform Amphibole Minerals by Optical Microscopy and Dssparsion^Stainielg Apparatus t. Polarizing microscope. Best results will be obtained if the instrument includes the following: . a.' Individually centering objectives -V;'/'J# ; i-xSk . ... ; : ; b. Bertrand lens . * `a - a 'J,/ ' -'.rvG. " High-Intensity light source " ; V; . V:-.?`V Centeringcondenser/substage ""^y - ' : - v 2. Dispersion-staining device (Note 4) cup "i, Reagents ' :/ :\ - v .'V-.V* 1, Hydrochloric add, 10% v/v . . J /-y i 2. Cargills immersion liquid Series HD^ n f* = 1.605 (Note 5) ^P rocedure '1?! i Acid Treatment vfW 'Ci * . > ........ - - r ' B e c a u s e of the interference caused by some carbonates (e.g. caldte) in the detec- ty-i}' ' . Xi:,Jf;,?"'c.^-'- r \W>l' .it ;U T- >-/ : V.'\si '-* ^* ;/ ' ' n v 1 * ` *. *> ,::;e ..u y * ;vv r ' ' '.A, <: * '* * 3: . i** *> " - - *. - ' f * * *. : *' >V;X 7 v- - i-i?; y;;' s. - . * * l ' ' v .* ; ** f - !:?^ j.. vw-i:*vK-!'.ivrfWr?- 'S* ' : , ' >>: / 7* . t n* *' '' ' .... >k rx^i-W J - v/ r V .. - A ::'C ; ' \ ;... , . '. v -i- -..' ' j ^ _ < .. r^ ; -: . ^ ... ;a r- . *' r" ' ' . ` . , >. CTFA m Weigh out 2 g of the talc Into a 100 ml beaker. Add 25 ml of 10% v/v HCI slowly (to prevent excessive evo 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. O ptical Microscopy and Dispersion-Stainmg /* , Carefully disperse 0.1 mg of talc in one drop of Cargilie HD liquid, rip= 1.605, and cover with a clean ( Examine the sample in the dispersion-staining central stop mode. The substage diaphragm should be < position. T V :: -".5-:'v.vv '/ Zv vV- ' -H >' :T . V - .; XV o: ?f X- ; ; ^ :j-. V1: . T r e m o l i t e , actinolite and presumably, other amphibble minerals, under these condi- tions, will show the .following- dispersion-staining colors: yellow changing to blue ' ; with rotation. The variation of the color change is due to the fact that the tremolite *:\/' l-` V- -V/ : *_v' - Z1- . v* " >: Examine the sample for asbestiform fibrous amphlbole mineSrfaalsiS^Z (Reference 4 )/ " * ; Zi r v's- : ..v . . -..v 1 ' .- .' -. * ' " ..v . 1 . Particles must appear to be fibrous rather than as crystals-or slivers. \ 'v..Z- .1 . . 2. The maximum diameter of a fiber to be counted in 3 h i i c r o n s . ; .; .:)> -. 3. The maximum length of a fiber to be counted is 30 microns.'X-'i/.;:. X- V : T 4. The length to width ratio must be 5 or more to 1, that is, 5 times or more longer than wii 5. The separate or individual fibers must contain fibrils or the " bundle of sticks" effect, unless 1 nondivisible stage. A fibril cannot be subdivided and would be counted, if it meets the other ( length to width ratio of 5 or more to 1 is not meant to imply tnat other particles are not h CTFA Method Issued: 1 P Report results as "Asbestiform Amphibole Present" or as " Asbestiform Amphibole Absent." It is imperative that both dispersion-staining color and fibrous morphology criteria be satisfied before identifying a particle as asbestiform amphibole, since other sub stances may show colors similar to those described. ; . Notes . . . ' . v ^ V v V ' -..'' , " t. Talcs to be analyzed and the tremolite used to prepare standard samples must be finer than 325 mesh (i mum particle size of 44 microns). The Tekmar Analytical Mill (Model A-10) is recommended. It is available -v . r . v :;V ' 11 Tekmar Company . } . - f ft; r -A lC Box 3 7 2 0 2 ` ' v '* ~ ~ f. ' v ' v *- ^ ^C in cin n a ti; Ohio 45222. : 2. It is important that the homogeneity of the prepared talc-tremolite standard samples be verified by o] microscopy.' . ; ' / 3. This requirement is critical since excessive surface scatter will cause abnormally high background co 4. The only commercially available dispersion-staining device is sold by: . :; /^ W a lte r C. McCrone Associates, Inc, . \ '/ . -i i ?820 South Michigan Avenue ; . . : 7V.77 Chicago; Illinois 6 0 6 t3 >-/, 5. Available from: / ' *' T'.,:y:- y ' v : i: v '/: \ "'-V: )%'?.;} R-P CargilleLaboratories, Inc. ', '-7' y \7 s;.'-Cedar Grove, NewJersey 07009 ; ; -- orfrom laboratory suppliers. .. W .. . /' ; r '. / -; ;-v ' > References /. t . Rohf, A. N., Langar. A. M., Environmental Health Perspectives 9,95 (1974) ; 2. Rubin, I. 8., Maggiore, C. J., Environmental Health Perspectives 9, 81 (1974) 3. L S. Blrks, X-Ray Spectrochemical Analysis, pages 54-55, Interscience Publishers-(1959) 7 4: ``Trem olite and Tialc." if. S. Department of Labor, Occupational Safety and Health Administration, Field Infc tion Memorandum # 7 4 -9 2 , November 2 1 ,1 9 7 4 . ^^ CTFA M FREE C R YSTA LLIN E SILIC A (QUARTZ) JN TALC {DTA Method) P rinciple Differential thermal analysis (DTA) involves the measurement of thermal reactions which are induced as it is being heated at a constant rate. First-order thermal transitions are denoted as endothermic or depending upon whether the process is accompanied by the absorption or release of energy in the form sample holder includes a reference thermocouple and a differential thermocouple, which detect thermal i continuously monitoring any difference in temperature between the sample material and a thermally ine substance (calcined alumina) contained in another cavity orsam ple dish of the holder; *fy'A- The DTA method permits the unequivocal detection of quartz (free crystalline silica) in talc at a 0.5 t minimum detectable level. The method utilizes the thermal transition representing the reversible alpha to inversion of quartz at 573C. On heating, the latent heat of inversion gives rise to an endothermic reaction an exothermic transition is obtained. The talc is first calcined at approximately 800C for the purpose irreversible thermal transitions attributable to mineral impurities. The cooling curve then shows a flat bs improving detectability for quartz. Studies have shown that the intensity of this thermal peak is affected h) size distribution of the quartz. Therefore, DTA is not recommended for th quantitative determination of c Apparatus i* Differential Thermal Analyzer, including either a high temperature powder sample holder of nickel steel construction with exposed-loop differential thermocouple (such as Pfatinei II) or sample holds a ring type differential thermocouple with platinum dishes, with equipment to heat to at least 800C 2. Spex Mixer/Mill, or equivalent mechanical mixer with plastic vial and plastic ball T :; : j ; 3. Sieve, 325-mesh ; i v ; !:T ; V- V- . 4. Mortar and pestle, or grinding mill ', Reagents 1 . Standard talc samp|e, containing no detectable quartz 2. Standard quartz sample, at least 95% pure Procedure . 'V . ' ;-V: ' Standard Preparation v -v T / Grind standard talc and quartz samples to pass a 325-mesh sieve. This will give a particle size distrib Weigh appropriate amounts of the ground standard talc and quartz into a plastic vial to prepare 1.0% w/v standard. Mix with a plastic ball approximately 10 minutes in Spex Mixer/Mill. CTFA Method Issued: Instrumental Parameters Experimental conditions for a typical DTA unit (Stone Model RC-202C or LA-XYH) are as follows: Sample holder: high temperature powder type, of nickel or stainless steel construction (Model SH-8BE2) exposed-loop differential thermocouple (Platine! II), imbedded reference thermocouple (Platinel II or Chr Alumei) , Temperature range: ambient to 800C ; ; Sample: 130 to 150 mg talc, using a loose, consistent packing technique Reference material: alumina, ground to pass 325-mesh sieve . ; 1 Atmosphere: static air Heating rate: 10C/min v: : Sensitivity: 40 sAvolts full scale : ^ "> * V.\ /,,..-l .: N ' . . ; Furnace: ITF, water-cooled to 1200C / V;-- . :-; > V instrumental parameters must be determined for a particular differential thermal analyzer such that 0,5 to 1.0% w/w. quartz in talc may be detected in the cooling curve subsequent to calcining the talc at 800C. Once these experimental param eters have been determined, they must not be altered during the analysis of talc samples in order to assure instrument sensitivity. It is emphasized that reproducibility of the method is based on standardizing the ;; experimental conditions. :w . . Run the prepared quartz-talc standard to optimize sensitivity of the instrument. v '- .y / f. the quartz inversion endotherm at 573C is masked by thermal transitions / ' - .T > of mineral impurities in the talc, it is necessary to rely on a cooling curve for quartz detection. If there is no provision on the OTA instrument for programmed cooling, ' V' ; heat the talc to 800C, cool to room temperature, and record the thermogram on r : ; ::,v.:ire hedting for detection of quartz; *; ~,:rA.;SYV'V. V O . - ' " ` t Grind talc or talc ore samples to pass 325-mesh sieve to give particle size distribution comparable to standard sar Run the prepared talc sample under the same identical conditions as the standard. Detect the quartz by means c crystal inversion at 5 7 3 X on heating or cooling (Notes 1& 2). Report results as " None detected," or as " Equal to or greater than 0.5 to 1.0% w/w. ` fU`\ '' '.Notes ; V/-. v t . The value of the DTA method lies in the specificity of the determination over that attainable by x-ra; fraction in the silicate mineral matrix. No other mineral has been reported in the literature to ha ' thermal transition peak at 573C. Semi-quantitative DTA is feasible only under fixed expertm< conditions and with some knowledge of quartz particle size. 2. If semi-quantitative estimation of the quartz content is desired, this may be achieved under fixer perimental parameters by comparison of quartz peak intensities obtained for additional quartz standards (Figure 1). The particle size distribution of the quartz in talc samples and standards mu; - as consistent as possible. VT' CTFAV wi FREE CRYSTALLINE SILICA (Quartz) IN TALC ' : . . y ':!* y :y P rinciple p (X-ray Diffraction Method) \ . ,.y'-AA silica (quartz), in talc. It is necessary that at least the three strongest diffraction lines of quartz be presen pattern to confirm the presence of quartz In the talc: 3.34x, 4.264, 1 822d. x-ray diffraction pattern having more intense quartz peaks than the pattern obtained from a packed-powd the same talc. Using this pressed pellet technique, M is possible to detect the three strongest quarts minimum level of 2% w/w. :,&...:!*.v.' ... . " " ' r A->1<* -ov,'.: Apparatus : 1 -- ;' K ;:^v 0 4^ ^ ; 1. X-ray diffractometer with nickel-filtered CuKce radiation and a suitable 11/4Wcircular sample h( pelletized sample . ' A y y ,;o ~*v > & y-$V' i; y y 4 V>. yyc* ^ ;vy .'i * TC*v-s-i *,*' '*\ 2. Hydraulic press capable of maintaining from 15,000 to 24,000 lb (as calculated on a 3" ram) ',,P ;..- "Via, ';44?;^ ^ ^ -V, S /'V v : ^ >y * :`y .. Heagents .: * ' ' ;p r*` 1. Boric acid ;* * " . - :*"Iy ... . vi ' -v' ' Proicedure ;' ' / \ y , 'i-V.';' . y< '.V;. "y . ;y.``'f.-'. Y \ 'f1lyi!i>"V y" >V/y--'-.-,'-i v y : y-'" -v y y j'l l - 'J-'" -y y - ,v.v ]'''*y- i"-' y .i"y 4 Sam ple Preparation Transfer approximately 2 g of sample talc to the die-holder and distribute evenly on a polished, scratch fi distribute approximately 4 g of boric acid on top of the talc layer. Compress the two layers into a pellet wh< is free of flaws (Note 1). y \ r v; : y y ^ / y y :C. . y . . y y y '? ; .y y V* . ` fe-- 4. I .A' v .. ;y * `*V c- ;y; `V. r -y :... -i:. / :- y ; 'KV' y ^ y y y y =vy v.y> -y\;-. v :- - v y y `-y, ;-.y y y ; ... y y ' y . y v\ >; ^ y V?y.-vy s y . y . v . -T A CTF Method J Issued: 1 F Instru m e n ta tio n -. Scan the sample pellet by x-ray through the three analytical quartz regions under instrumental conditions which \ previously been determined sensitive to the 2% w/w quartz level. As an example, the following conditions have been employed on the Siemens Diffractometer (Model No. M386-X and Siemens Counter and Recorder (Type T): Radiation: Cu-with KBfilter at 40 KV and 24 ma Divergence slit: V20 Receiving slit: 0.2 m m . Goniometer speed: V22^minute y . - Recorder speed: 600 mm/hour j'V-.-' ; - Attenuation == 1 x 103impulses/second y : Time constant, TES] = 1 v y . y.-y-'y Risatime = 0.18 .. .Attenuator = 20 . y . y ' } \ - ;-' V ;, v y ; . /, ' _ "j;' \ y y y - Y y - 11 : y '.y^; X-Ray Diffraction Scans First scan the sample pellet from 25.5 to 27.526for the presence of a peak at 26.7 (0.1) 20. If no peak is detec quartz is absent at the lower limit of detection. If a peak is observed in the above scan, then scan the pellet through the 19.5 to 21.5 2 ^region for a quartz reflects 20.8 ( 0.1) 2 d, The absence of a peak confirms the absence of quartz at or above 2% w/w. Report results as "Non detected," or as "Equal to or greater than 2% w/w." Notes'. T. The amount of pressure necessary for a good talc face may vary from talc to talc and can only be determ : experimentally. . Y: ,y lv ' . ' *.