Document 91G5BdrxnDMy3qYVRJ7rVm0mL
The Cosmetic,Toiletry and Fragrance Association, Inc.
,1133 15th STREET, U.W., WASHINGTON, D.C. 20005 202/331-177D TELEX' 89-2073 '-
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MEM'O RAN'D UM
. Jan in s H. Merritt * Pnsstd&fii
Norman E. Eatrin, F'h.D, Wc Pirsklon!-- Soirncc
E. Edward Kavanangli Vina /'ipsMeuf->
Cofty/'osiiofutf Ri'ilions
Margaret W. Smith Lxccutivc Secfiflaiy
TO: The CTFA Talc Subcommittee
FROM:
Forman F. Estrin, Ph.D,
DATE: November 2nd, 1976
SUBJECT; CTFA Talc Methodology
McCrone has performed a very useful service by comparing and' evaluating CTFA methodology.
Their suggestions with regard to methodology and their other suggestions should be discussed at the November 10th Talc Subcommittee meeting.
NFE:jj Attachment cc: Walter C. McCrone
waiter c.me crone associates, inc. 'itliiitCO%SuLTit.SUi."KA.U:;SOANALVSlS-MiCTOSCaFY-SHU'.?ART,CijPBOtlLEl.tSSOU57A7ECKrUiSvTBY
'3 September l?7fi
Dr. Norman ?. Estrin CTFA 1133 15th SC. , Washington, DC 20C3
Dear Dr. Eatrinr
As you know, va, at McCrone Asrociates, have done ctasideraklc work on calc and especially or. various mineral zrjritios in talc. As a result v* have accumulated data, procedures (and prujiidiciss) cojr-c-err.lng these analysts. ,
I have recently had occasion to look at the propored CTFA procedures for asbostifam minerals in calc and w n rt ,slp feeling that our routing procedures are I regret to say considerably wore sophisticated, Since I vas about to coTm.it our methods to a. paper for another publication '(unfortunately, for the FDA)-I felt that, as an intellectual eaerciso* I would recast the B'.no material as a CTFA method, I aa enclosing this horrendous document tor your perusal and syzipnchite if ycu choose to quickly burn it at the scales. Note first, however, that I have retained BO=te of the featurfes ct your necked `that I liked.
Still, in cur hands, the irjathods ve propose work very well. In addition, they are rapid and reasonably inexpensive. lie ere interested in improving the competence of nicroanalysts generally and, as you. nay know, teach about '40 courses a year in these procedures loth heTe and abroad* As a tatter of fact** I l.Gsve this weekend where I will be teaching 3 back-to-back courses in the idebcifiCBtion of asbestifom minerals ,by the methods covered in the infatdcus enclosure*
Seriously, I don't propose yon adopt these methods in the detail 1'vo L.us3,5stcd but X do suggest that you urge each CTFA rrembar to cake steps now nl.nti will lead to cheir ability to m-oke such analyses. The rare each company knows about the products it tiskes anu the raw materials it uses the better able will that company be to .jesy out of trouble and represent its best intferescs if trouble arises, Tie can help here through our teaching a m . I suggest *?e offer a course either directly through the CTFA.or simply to the member ccmpnaias. This course weuld train one-or more qualified nicroanclysrs in each company in the use of the proposed x-ray diffraction and dispersion staining methods for the study of cosmetic talc and possible contaminating substances
Ve would further aid each company in setting up (purchasing, if necessary) the equipment, supplies and mineral standards required for atieh studios. The entire package would include a one-week intensive course in Chicago, evaluation o f the company laboratory and equipment, furnishing sets of
$70SOUTHliiCHIoANAVcfaUE.CHrCACO,ELtWOlSf,?S14.3176J2.T133.CABLE;ChEMICnO^E
Fornan F. EsCtXa PtgC: two
standard samples- and test material and .a follow-up over a several-month period of progress in esch company by means of -a series of rcund-rctin sample analyses. We vill sign off each cocp.sny vhen vc arc satisfied their personnel and equipment can do a professional job of analysing talc samples. The cost of this package would be $1300 per company.
I look forward to jrour response and hope I haven't scared you way.
Yours Sincerely,
tfCH:cdh
Enclosure
Walter C. XcCrone
COStiETlC TALC
El PIXITION:
Cosr.etlc T-le is a white, essentially odorless, fine povderr ^rauo.J iron naturally occurring rock ore, consisting mainly of hydreted r-agneslua silicate having the ideal fori.uls
' fOH,).with lesser amount* of naturally associated rafiera.r'Such at calclte, chlorite, dolomite, kaolin and ^egrtesite, and containing no asbestos minerals detectable by x-ray diffraction.
TEST
SPECIFICATION
. >CTiQD
Color.'. Odor. Identification
Slip*..*......... Lustre. ....... *. Uater-Solublc Iron. Screen Test,*.*... Veter Soluble Substances...
As specified by the buyer and shoving. no change tar heating
Heat 1 to 2 g at. 20G*C for 5 minutes
Ae specified by the buyer
CTFA C 3-1
Positive:
1. 'Close match to CTFA
Spectrun with no in
dication of, foreign rii-tcricle
CTFA G 3-1
OR
I. {Alternate) Clone natch ASTW D 934-74 Powder diffraction File Ka. 19-770, published by AST>i, showing the cost intense reflections at d vclvec ebout 9.35, 1*53 end 4.59 A .
As specified by the buyer
Bo.
Passes test
US? XIX, page 487
1002 through 100 mesh 901' minimum through 00 nosh Finer grades: as .specified by
the buyer `
CTFA C 5-1
0.12 maximum
USP XIX, page 4S7 See tust for JrRcactlon and Soluble SubstancesIr
Acid Soluble Substances*.*
Loss of Ignition.*.,...., Arsenic '(ils As)..... .
As specified by the buyer 6.0% naxizun
5.03 caximua
3 ppa naxiunss
Lead fas t f b ) .....
20 ppa aaxiwua
Amphiboles. ............ .
None detected by XSD
(Aslestiforn Trencllrc fit *1)
Free Crystalline Silica.... (Quarts)
As specified by the buyer
CTFA E 33-1
L'S? XIX, past (S7 CTFA F 1-1, Farts 1-A ar.d 11
CTFA F 2-L, Farts 1-A w.d 11
CTFA J 4-1
CTFA J 5-1 (STA) Alternate: CTFA J 6-1 (X-ra/)
ACID SOLUBLE SUBSTANCES IN TALC
Principle
A sample of t z l c i s isixud with diluted hydrochloric acid &ad the insoluble portion. is removed by ' centrifugation and filtration. The filtrate Ik sulfeted, evaporated to dryness and ignited. The acid soluble natter is determined graviniutricelly as the sulfate
1, Controlled temperature water bath 2; Beaker, Griffin, 100 ml 2s Volumetric fls&k, 50 nl. 4. Centrifuge 5 Ctntrifuge tubes Cl), 50 ml
6. Graduated Cylinder, 50 nl 7. Sintered glai.,? funnel, ultra- fine porosity, 0 p 1 {0.9 to 1,4 v*0
Corning :;36060-UF or equivalent 3, Vacuun flask, 125 ml
Fipecte, 10 al '
10. Platinum. or Vycor evaporating dish or equivalent
Reagents
`
1. Hydrochloric Acid, diluted, 10Z v/v
-2, Sulfuric Acid, diluted, 1I v/v
Procedure
Vei'h 2 g (0,001 e ) sample into* a IOC fcl leaker, add iO ttl
r.diluted hydrochloric acid, and place In water hath at *55* (2,5*C), vith occasional stirring for 30 rilnutes, , nmcoiately remove leaker from lath-and pour contents Into a 50 -ml centrifuge tube, rinsing leaker and stirring bar with 2 to 3 nl of distilled water. Centrifuge at 5000 RFK for 30 rdnutes Oiota 1).
Filter supernatant through ultrafine porosity sihtured glass funnel
into vacuum flask, using 2 to 3 ml of distilled voter to rinse the centrifuge tube and funnel, and using care to cvold dislodging the packed calc at the bottom of the tube. Filtrate r*ast be clear (Note 1), Four filtrate into 50
ml volumetric flask, rinsing with 3 to 5 sl distilled water. Adjust to volume with distilled water.
Pipette 25 ml of adjusted filtrate Into rared, ignited evaporating dish. Add 2 cl of diluted sulfuric acid and evaporate to dryness.
gr.ita at 00* C25f'c) fer 1 hour. Cool end vaigh. Calculation
X Acid Soluble Substances 'teight of Residue in g x 200 - Vei^hc of Sample in g
Kccc 1* Examine the centrifuged sacple carefully to assure gnod clarity bfir-
fore proceeding with filtration* If haziness is erected, centrifuge the sample for an additional 15 to 30 minutes as necessary*
ASBESTIFORH MINERALS IH COSXETIC TALC The presence of asbestifora minerals in calc is determined by x-ray diffraction with a-sensitivity of about 0,5% by weight. The mineral identi fication ^Is confirmed and the dsbestiforn habit is determined by polarized light microscopy with the added help furnished by dispersion staining*
If >0.5% of. asbtscifom mineral is present the sample is rejected. If the non-asbestif orm habits are present t e, g., llzardite, aiitlgorite, gruperite cuitmingtonite and reibechlte the snoole passes.. If <0.51 of the &a-z bcEtifona hah.lts ate present the sample passes. (Koees The polarizing micro scope with dispersion staining will detect 0.01% of any mineral vith net more than 30 minutes scanning tltne and if the particles' are, at least 0.2 x 3
pn.>
m i I -- ASBESTIFOSM hlKERALS 3Y X-RAY M FRACTION
Principle The x-ray diffraction method is based upon the principle thrt vhtn
a crystalline material is placed in an x-ray beam* a portion e the x-rays are diffracted by each set of atomic planes within tht crystal- The diffrac ted rays strike a scintillation counter ,as the sample is scanned through a prescribed angle ylth. the resulting development of peaks corresponding to each interplan-nt distance (d). A peak with a d value in the range of .8,04 to
B.&5 A for a talc sample I s strong evidence for , the presence of amphibole.
The limit of detection of aarphibele by careful application of this me thed is 0.5X.
Apparatus
1* X-ray diffractometer* employing* aickel-filtctcd copper K-alpha radi ation'* horizontal or vertical goniometer vith variable scan speed capability, suitable talc pellet sample holder, variable speed recorder, electronic panel Including rater.cter, variable attenuation and tine constant settings
2< Hydraulic press, capable of attaining a pressure of 15,000 to 24,000 lb applied to a 3" xaa
3. iiortar and pestle or grinding mill (Kote 1) 4* Storing Blunder, or equivalent blonder 5. Sport ilixer/Kill, or equivalent mechanical uixer 6* Sieve, 325-nosh 7. Optical microscope (Kote 2) 6. 1-1/4" pellet press
Renr.gnts '*
1. Standard calc sample, conta.ir.ing no detectable axphibole minerals
'2. Standard trernolLtc sai^lr- (at leant 55T pure.), 'r.ay be obtained by ordering ftern The Ccsiiutnc Toiletry and Fragrance Association, Inc., 1133 Fifteenth Street, lf.Tfl,, Washington, D.C. 20005
3. Denatured ethanol
' km Boric'acid
Procedure
The procedure consists o scanning (l"/ain) under otherwise high
tivity conditions, a-compressed pallor of the sar.ple talc over the 2 range
iron 4* to 34*. (about 20 A to 2.6 70 with Ctt Ka radiation recorded, trace for the peaks tabulated in Table 1.
Chech the
" TABLE 1
f
Possible Characteristic Strong Teaks in the X-Eay Spectrun of Talc
20, dep.fecs
6.31 9.45 9.66 10.51 10.51 10.55
10, SI 12.01 12.04 12.20 12.51 18.99 19.52 19.45 19.46 20,49 20. S3
<n' CO
d, A
14. D 9.35 9.15 8.40 6.40 8.38
7.36 7.34 7.25 7.07 ' 4.67* 4.59 4.36 4.53 4.33 4,26
I
B0 100
20 100 100 100
100 100 1D0 ICO
a
a 45 25 12
6 35
Klcercl
chlorite talc cumins touite (aaosite) erocidolite hornblende crc^olitc, actlnollce,
anthophyllite ouititingtoaite chrysotilc 11 aardite. imtigorite talc talc talc talc talc talc quaxtr
23.02 24.30 24.50 24.57 25.25 25.SS 26.64 27.26 27.33 27.59 26,59 2S .60 23.60 28.63 2S.77 29.16 29.55 30.96 31.60 31.76 31.82 . 32.19 32.46 32.63 32.S3 32.90 33,09 33.15 .33.19 35.60 35.85 35.04 ; 36.56 - ,, 33.49 39.40 41.40
3.S6 3.66
- 12 100
. 3.63
60
3.62
60
3.541 -
80
40
3.343 3.268
100
75
3.26
30
3.23
50
3.121
100
3.12
40'
3.12
55
3.11 ICO
3,10
70
3.06 100
3.02
100
' 2.885
100
2,829 2.614
20 100
2.61
100
2.773
60
' 2.756
70
2.742
100
2.776
40
2,720+
60
2.705
90
2.70.
30
2,697
20
2.52 2.503
90 18
2.49
ICO
2.456. 2.337 2.265 .
` 80 2
13
2.192;
30
calcite cbrysotile lizardito intimorite Chlortc apatite
quarti
trenolite hcrablenda cprhopliyZlira trenolite tale crocidolite actindlite hornblenda 7i.chitpiiyi.lite, anosit.e calcita dolonite etilorite apatite calcite apatite anosite tgec3te crocj.ilolite apatite craiiiclite aetinolit hornblcnie intimorite CdtcesLe lizerdi te chrysotilo tale calcite dlooite
41.98 42.99 49.08 46.81 46.05 40.65 50.16 50.55 51.10 51.25 53.88 59.26 '60.24 60.41 60.50 61.80
2.15 2.102 2.095 1.94 1.692 1.870 1.817 1,804 1.786], 1.7BlJ 1.700 1.556 1.535 1.531 1.529 1.500
60 45 13 12 50
4 17 20
30
3S 2 60
70 55 60
literdire magnesite calclt.<i esjpiesic trejrolite talc quart* dolomite
dolesite
magnesite talc. elitysotile lizardite talc liiardite
Some minerals, e,g.. carbonates* quart**., hornblende etc* have been listed here net because of any known harmful effects but because they nay be ob-* served in talc saoplcs.
Under ideal conditions 0.5-1OX of all of the above minerals should be Indicated by a possible peak in the 4*-34* range. Appropriate peak re gions for the indicated mineral should then be scanned at 0.1V e i n as indi cated belou.
Should the presence of a email peak above the background "noise" be in question, it will be necessary to statistically evaluate the scan cade at 0,l*/tain in the suspected peak region (s). A timer/scaler Is required! on the electronic panel of the x-ray difiracto-acter* In order for a peak to be sta tistically significant, the peck Intensity must equal or exceed three stand ard deviations (3c? ) above the average, background intensity (1?)t
N + 33 * minisauai peck intensity* IT - average background count j W i T
"Peak1*
10.0
10.2
Pigrc 1
"A" .
10.'3
10.4
10.6
10.S
10.7 11.0
*20
Example: In Figura 1,
Beak Background
Region S-...-L,...
Region *2 0 J
Time (see.)
10.40 to 1 0 .6 D '
120
10.40 1 10.70
60 60
- Background
Peak 10.40 to 10. 60*25 tine sees. count
Region A
10,30 to 10.40*25 tlse' :-C3. count
Region. 3-10,60 ta 10 ,,70*26 tina eses. counts
110 . 120
110 Average
0,332 S9.B70
60,105 60,101
60 IS,764 '60 23,943
60 23,634 28,787
60 23,506 60 28,368 60 23,204
28,359
S " 28,737 + 23,359 " 57,146
- 57,146 - 239 3J 7 71,7
N + 3J ^57,140 + 717 = 57,363
The actual number of counts obtained fat the integrated peak inten sity ves 60,102; therefore, the "suspect" peak is statistically present in the scan.''
Standard Preparation Optimal inscrucent conditions must first be determined uith the use
of standards containing 1,02,' 0.751, 0.52 by weight of the-suspected contami nant prepared in a standard tal which-is free of interfering peaks.
Welsh out appropriate amounts of the standard rale an6 the mineral
' peas aof interest both of vliich have been ground to
325-=cfih sieve.
TrAnafer to a Waring frlendor. Add 100 t! of ethanol to the blender and
blend at low speed for 5 minutes.
Carefully transfer, with repeated ethanol washings, the contcate of
the blcndjr Into .a large beaker. Evaporate the ethanol on a steam bath. Shake the sample in a plastic vial for ` 5 minutes on e Spcx
Mixex/Hill to remove clumps and caked sample resulting from the evaporation
of ethanol.
Determine by microscopy the homogeneity of the prepared standard
previous to Che x-ray diffraction analysis.
Press the homogeneous standard into a 11/4" pellet with a backing
of borie acid. Transfer 2 (0.2) gram of standard to the die-holder and
evenly distribute on a polished, scratch-free die. Distribute 4 (0.2).grams
of boric o d d evenly on the talc layer. Press the mixture into a pellet un der conditions suitable for obtaining a smooth planar* surface (for example, a
pressure of 15,000 to 24,000 lb calculated on a 3*' rats has been found to pro
duce suitable pellets). The resulting pellet must have a tale face which in
free of lavsj If not, the pellet must be discarded (Kate 3).
Sample Preparation Prepare two pellets from each sample in the manner described for
the standard pellets. Make a qualitative scan from 4 to 24*26 on one of these pellets to ascertain the presence of nor--calc minerals having interfer
ing peaks.
Ins cruttenis. tion Instrunental variables ere optimized on Che IS standard, Lover standards eve then analyzed under the 'optimum conditions to deter mine the lover level d detection Of-major importance In obtain ing maximum instrument sensitivity are r slo v diffractometer speed combined with compatible recorder speed, and high attenuation com
bined vith a statistically acceptable time constant on the ratriae-
t Under appropriate instrumental conditions the peak obtained for thii 0.5% standard should be detectable-above background noise as shown.
In Figure 2. for trcr.olite*
Typical instrumental conditions employed fo* the Siemens Diffrac tometer (Model No. M3S6-XwA4)a and tountcr and Recorder Unit (Type T) are:
, Radiation: Cu vith Kc filter at 40KV and 24 mA
Uivergence slit: 1D Receiving, s l i t : 0.2 Eaa`(.007M)
Goniometer speed: iyiO*2@/mlcuce Recorder speed; 3C0 rnn/hour Attenuation: 1 x 103 inpulses/sccond Tine constant: T () * 4
Statistical error of 1.1% under these conditions Rise Time - Q.lfi A tte n u a to r " 20
TART 11 i AShEExIFORM AMPHIEOLK
BY ?0LA?,r2El> LIGHT
MICS02CCPY AHD DISPERSION STAINING
Apparatus
^
X. Polarasi^j* rcicroscopc. Best results vill be obtained if the instru ment include* the following:
\ a. Individually -centering objectives or centerable stage
b. Icrtrsnd.lens
c. High-intensity light source
d* Centeringcor-denter/suletava
2 , Dispersion staining device (Kpte 4)
3 . Vacuum filtration equipment^ Including either e. porcelain cone with glass fiber filter cat or a porous glass bat tor. cup -
.Keagonts
*5
2. Cargillc iemersion liquids* n& 1.550 (ID series); (Koto 5)
n*-5 - 1.605 <1
)'
Up5 - 1.660 (Iff " )
n^5 - 1.710 01 '' )
Optical Microscopy and Dispersion Staining Carefully adjust the dispersion staining objective for optimum
viewing of central stop colors* The microscope is first'arranged for Kohler illur-iinatioa: lamp iris (field. dlaphraa) in focus in tfce field of view; leap filament in focus In objective back focal plane. The lamp, if movable, should be placed' close to the nirror so that, the image of the lamp filament Is as snail as possible in the objective back, focal plana. This along with oyervoltinfi the lamp by 15-2G'? and removing the daylitc Vlud filter will .ensure bright central stop colors and detection of subnicronetcr particles*
The stage should next be centered and the central stop should he precisely centered vich respect to the image of the substege iris (aperture diaphrea) in the objective hack fatal plane. The substage .iris is then closed just behind the central scop and the Bertrand,lens {or equivalent vievinfl systesi} is removed. * The preparation is scanned for Xq colors in the visiblej critical study- of *n area or of a given particle Is carried one with the field dlaphra* nearly closed around 'the center portion of the field of view.
Identification of con-talc mineral by dispersion stlining. >iount a representative -sample {about th\ me) in the following Car
gill refractive index liquids and examine carefully for non-talc substances. The particles are mounted in the drop of Cargill* liquid between Slide and coversli?. The particles are best dispersed by sliding the covorslip with a rotary nation of a pencil* eraser "gripping" the'coverslip.. The final pi-cp should be thin and the coverslip should be parallel to the slide (this avoids a "prism" shaped prep that will dceeater the image of the substage iris relative to the central stop}* The slide and covers!!? mast be carefully cleaned before use and the pencil eraser oust be- 'dipped in diluted rubber cerntnc and dried before use to avoid transfer of particles to the top of the coverslip. The minerals to be checked for includes
a' or e
Refractive Indices S Y or
chrysocile Wizard ite Antioritc Chlorite Quarti Caldee Dolomite Kagndsita Hornblende Forcterito ' Talc Anthoiihylllw TracoliCQ Aetinolite
Arosite
Ctocidolite
f Cutanlneconite
1 Creatrice { Clcuco^hanc [ RichccV-lre
1.543 1.545 1.564 1.600 1.544 1.658 1.679 1,700 1.655 1.640 1.540 . 1.525 1.599 1.62S 1.646
1.660 1.630
1.695
_
l.566
1.603
1.665 1.656 1.569 1.635 1.612 1.640 1.658 1.70 1.640 1.704
1.556 1.556 1-570 1.610 1.553 1.466 1.SG0 1.509 1.672 1.674 , 1.595 1.650 1.622 1-650 1.674
1.715 1.645
1.710
Minarais*- especially silicates* but also- the iseniCr'phous series of
carbonates (esleite, olo.-its, ru*ncsit& etc.) - vary. ,ir, refractive ndex.
Figure 1 a. and b. shov average indices for the minerals which right be found
in calc. Generally, the dispersion staining curves for these minerals move
parallel to themselves as the composition chances. The birefringence values
(7 -E, E'-q and c-u) vill generally remain nearly constant for 4 given mineral
although the indices thcns'cives may vary consider'nbly.
* The combination of crystal morphology, 'and optica is also a gireat
'help-' in Bohins sure of the identity of a given mineral. One should loch for
different views of a given mineral and/or vary the view on a single crystal
by capping gently on the top- of the coverslip vith a needle. In this uny
fiberlilt* talc plates on edge can be tipped into the plate view and quartz
can be made to show c as veil as u*
.
Both morphology and optics are noted in order to identify the
asb-escifom-minerals. To be asbestifom requires that they be fibers, not
slivers, s-astiring <3 pm,in diameter, <30 pm in length and hove a length to . ,&
width ratio ot at least 5:1
Framiria the sam ple.jer nsbestiform or fibrous jetphihoje iTan.orfi_3jj_
In order for an snphiboio mineral te be considered, ashestiform or
fibrous it eyest meet the following 0$iA definition (Reference 41. 1, f a c t i c i a s must appear to be fibrous rather then as crystals or sli vers,
2. The maitimira, diameter of a fiber to be counted la 3 micrometers.
3. -The maximum length of a fiber to be counted 30 micromotors.
'4. The length to width-tatio toast be 5 or more to 1, chat is, 5 times r more -longer than wide.
S. The separate o r individocl l i t e r s zzu st contain fibrils or the "bun dle of stidt3,,*ef-Eect, unless they arc at a fton-dlvisible stage, A fibril cannot be subdivided sr.o would go counted* If it meets the other criteria. The length to width ratio of 5 or uorc to 1 is net meant to isply that other particles ere r.ot hazardous, .The analysis proceeds b y mounting the sample In successive Cargille
liquidy vith identification of each mineral shoving visible lg colors In each liquid. The first liquid is nD - 1.550
25 --Ca;--ro.illc- Ki-th .d1is*tn-e-rai-on lio"ui---dmn-.u " l--,550i
A representative sarpla, ebout 0,1 eg* counted in this liquid vill show characteristic Xg colors for any of the following: tale, quartz* chrysotile* lirerdite, ontigorice and nany fibers (paper* silk, viscose tiycr. and fcuncn hair etc,). The crystallographic data in Figure 2 should ensure lientificatlon of most of those substance.? ar allow the conclusion that any ocher substance shoving colors in this liquid is not one of those listed (Figure 1). Characterization of this extraneous substance vill often be possible by referring to the Particle Atlas.
CarfltUehluhdispersion iimijcjnjP1*6~>5a
Chrysotile and all other substances giving dispersion staining cclors in liquid 1.550 vill be white or pale*blue in 1,605 (Figure 4). Talc is the only substance in this group that shows a Xq close to the visible (ca 7G0 nm). All talc plates show both n 1s < 6 V) close to 1.605 in the red hence the central stop shows a pale blue in 3ll directions lying in. the talc plate and white corresponding to the c direction. Other minerals shoving colors in
* 1.605 include trc~,olite, chlorite and actinollte (Figure 5)-
Carftillc Llculd, * 3.560 (r.T series)
Non-talc minerals shoving dispersion staining colors in
" 1*660
include actinollte* forsteritc* hornblende, calcite* curraimgtonite and dole*
mice (Figure 6)*
K t h K A U l I V t . IW Ut, A UI- U A i t U I U L U U I U U I U
Figuri 2a. Dispersion staining curves,
.'
Figure b. Dispersion staining curves.
Talc:
(<4G0) Cn/ycllow <4Q0)
Qn-irtg:
coiicbnidal flakes, all.ehou co 680 nsj corresponding to u on.rotation of the'sees*; 9D* (roa che u orienta tion cither c (X 590 nn) cr ny c* <550 <X0 <6SQ). W
y **-- 1 | >-- --
white yellow
T vhiee-blua (*700)
Chrvrotdle:
a ,blue (6t.fi)
y- redTray.mea (520)
__.____i . ~____ y'- " red'raarf|inta (520) r J3-
fibers:
irregular rounded fibers
yellow-white
rpalc blue
Llsarditc:
f(&rc&Atcs of very fine plates, n*s rilJcht > chrysotilc* ft A y in `piano of plitCB X-^600 mi (blue
magenta).
AflClpbrltr ?
jS 410)
3 pale
pole tli-T17)yt-frlpia9lVe
ycllo:
y.u*
,il coition yellow (470) (ca 400)
Tlgur* 3. Central, stop dispersion staining colors in * 1,550 (110).
Car^Hlc Liquid Talc:
1 .G0 5 :
Trptaoli t* :
white i7C0>
Act ir>olitci
Figure A# Central stop dispersion`staining colors in Cargill liquid lip - 1*605 (HD series).
Accihalitc;
1f
)
a 4 v. p a ir b lu e (>>700),
/1
h`v * b lu e - g rr - m (c a 660)
T ...... ,: i
. 0 p ale b lu e (>700) +
! 1____
r'--
* nnle bit:!; (ea 700)
r&rrfcricpi
Calcite:
-biue-grcfin ( O)
1 yellow (430)' G j. ii. p a lp "bilie (>700)
b * \ ^bluc-Rrcn (6iC) "t
liornbUindc: Q y paalloe bmiinlge (>7Q0)
nr.nn^fp,pert;-Ciiji i|(fJi40)
' - i UIuc-i;irc-ce (6*0)
.r'~
'jlvse rta;-]aita (570)
Gilt,:-!:1-M Q n ire: a t i3*jt--t r e n ti (660)
j;io) -- ?---
P f blue (5SP) y 1- | r. j,0l^.c.n jKllgt, (510) ----- j-----------
y<g./. ..,,n^r 'Llo)
X jhiL ( 4D.0) white (<400) i" -- * vhite (*-"c5QD)
otite:
W biu^crion (700) ^ b lu c-g rce n (>700)
luo'-rcen (700) blue-green (70)
Tigers, 5, Cantra! atop dispi-rsien scalding colors in Cargille liquid ti 1.660 (ft? series)*
Cus- Orunorl tel
(=700)
(>7C0) C>700)
Crocldalito;
e. bloc (590)
klue-fji-fc :n (iCO)
*
y+ yollo'- (90) -- 1,f r'-pfivira (530)
Ha^nrsltc:
vhice (>70( blue (i'/C )
Figure 6* Central stop dispersion staining colors in Cargillc liquid Op " 1.7C0 (' series).
Cargjlle XIraid
1 .7G0 series)
Minerals to look fox la r.^ * 1.700 include euraningtor.itc, gruncs-
riti, crocidolite and magnesite.
Rupert re ..itlbis a* <fAsfroscjform Arephiholc ?rpsentn or_aft`V.sbe-itJform AttpM r-ole .bJznt.il
`It is imperative that both dispersion-staining color and fibrous
norphology criteria be satisfied before identifying a particle as asbestiforra
asphibolc since othet substances nay show colors `similar to those described.
yctes
1* Talcs to be analyzed and the'-jtandard minerals used to prepare standard samples rrust be -325 raeah (vaaslnum particle size of 44 mi crometers). t e ^ a T Analytical Mill {Model A-lOj ia recoEnaended. It ,is available from:
Tekmar Company P. 0. Sox S72C2 Cincinnati, Cll 45222
>.
2 Tt is important tint the hoT-ogeneity of tha prepared talc-cromolite Standard samples .he verified by optical.Taicreccopy.
5. This requirorient is critical since excessive surface scatter will .cause aoaornally high background counts.
4, The only commercially available dispuxoien staining device is sold by;
Kalcar c. VcCrone Associates, Inc.1 2S20 South Michigan Avenue Chicago, II 6051$
5, Available from:
?, ?, Cargill* laboratories, Inc.. Cedar Grove, KJ 07009
or ftoa laboratory suppliers
i
References
. 1. Kohli A. fi,, A. K* Langer, Envirciirencai 'Health iersijectivei: 9* 95
C2 5 W .
--------------
2 . Rubir I* B.t X. J. J-taR^iatc, Environmental Health Perspectives 5. ,81 (1974),
3* L. $. BirV.3, X-Rny Speetrocheiiical Analysis. pages 5455, Iater4 science Publishers (1959),
A* ^renolit*; and Talc.41 tf-S* Oe^artrsent of Labor, Occupational Safety and Health Administration, Field Information ifeosraaduo 074-92/ Hover-ber 21, 1974+
5. KcCrorte, V* C, and J. D.`Dally, Particle Atlas, 2nd Edition, Ann Arbor Science Publishers, Inc- (1973)".