Document 2RNoZ4wnbQYLDbVxgaaG6a85

/ 'T- . *1,. .4/moty>/irn'r L'nrirunmtni Pcr^amon 1'k`ss iy)n, Vnl. J. pf>. W.7 f.7U. Primed in lliiuin. VLAINTIHT'S y.xmuvi l'l>-77 DETERMINATION Ol- < IIKYSOTILE )N A1RUORN ASBESTOS BY AN INI RA-RED SI'ECTROMIiTRIC TECH N1QUE J. A. Ciadsdi.n. i. I`ahki.k and W. L. Smith Warren Spring laboratory. MinUtry nf `I L-clinoloyy, SiCM-naye, liens., l.-.K, Ilust lecTri'ri/ l Jttnr I*>71) tnitl iti Ji/tut Jnftn III Attaint 177(1) . Abstract--A new' method of tleleriimiiiir. chrysolite in iiirhorne ashesins usiiic infra red absorption at 7-77 pm is described, 'lire icchniouc is rapid, simple anil allows detection ol chrysotile down to about 70 i`g in the sample, provided that the serpentine minerals of related structure (e g. Kaolinilc) arc absent. INTIIODUC7 ION Increasing attention is now being paid lo the health hazards arising front the in halation of airborne ashcsios (II.M. Factory l.vxpp.rion.Ait. I96S), and in eim.cqucncc of this, improved methods for the determination of chrysolilc and other asbestos minerals in airborne dusts arc of wide inicrcst. Recently Curium \n and Martindalc (1968) have reported an X-ray diffraction technique which possesses a number of advantages, but which needs about 30 mg of sample. In this note we describe an i.r. spcctromctrie method used in this Laboratory for the determination of chrysolilc. The technique is rapid, simple and allows detection of chrysolilc down to about 20 /ig in the sample. The method suffers from the disadvantage of being non specific within the serpentine class of minerals. Jn the absence of other serpentine minerals e.g. kaolinilc, as was usually the case, the method is specific for chrysolilc asbestos, the form of asbestos most used commercially. .' EXPERIMENTAL TECHNIQUE " r* ' Chrysotilc in common with other serpentine minerals possesses a sharp i.r. absorp tion band at 2-72 /m tvhich is associated with the stretching vibration of the lattice hydroxyl groups present in the layer silicate structure. The band is fairly well .separated from the broad absorption arising from the free or weakly adsorbed water molecules present in most solid samples (see FlC. 1). The analogous bands in the amphibolc asbestos minerals (amosite, crocidolite, etc.) are considerably weaker and are not suitable as the basis for an analytical technique. ... - * " In this work potassium bromide discs containing known amounts of chrysotilt in the range 0-04-0-65 mg were prepared by the standard procedure (sec, for example. Martin, 1966). Values of extinction \ogl0f0/f, where J0 and I are the incident and emergent intensities of radiation respectively, measured at the peak of the 2-72 /<nt : y| band, were determined from spectra recorded on a Grubb-Pursons "Spectromaster" ` " : i.T. spectrometer, and were found to be proportional to the mass of chrysotile present in the disc (Fio. 2). The sensitivity of the method is such that at the lowest levels of chrysotile content (< 100 pg) difficulties arose in preparing standard discs containing such small amounts of material; however, the calibration graph is sufficiently linear !,. to allow a reasonable extrapolation, and indicates a lower limit of detection of ~ 20pg. W ' -u^.',77 >..' '>?'' V- .v.. ) * --- * - . -* *....... 7 ' ` ii SCF-FA-6312 PRODT irpn rv m-st>r> ij1'.'' t.: - ? **'i. v J-vnY'V#. !*.'. 5j..v.a-Vi'ttX. ';>. 'tur. i' j ' "-S .' C-'-.,;.' 'i '- *. '>... 1:. ':" '1 i. A. Cw>SDf.K, J. Paakf* and W. L. Smcth tlclernii All samples to be analysed filters. These were ashed at 451 filter and any carbonaceous transmission of the final disc decomposition of chrysolite is graph was considered ncccss; preferable to construct the c; same way. The residue in the and the amount of chrysolite j aid of the data set out in Fic lamina of KBr is pressed at : Since the material was concent considerable increase in sensi paring and calibrating such d Nevertheless, careful use of a satisfactory measurement to - i - ... . ' j ! ! ! This metbod has been used in this Laboratory. A certain amount of field w. the standard volumetric instrui in the United Kingdom, with Whatman No. I paper. Filter j for long periods. Short-term, hi a car park with a foundation asbestos waste. Where long period sampling the limit of detection of the tc was below a value of 0 05 fig m papers by elimination under ; Hm in length. During short-term snmplinf found in mensurable quantities about 1 fig m**. 'i Amounts of chrysotilc in the i j, The method combines a low lir specific; other serpentine min*. 2~i' I similar absorption bands at ' determination based on the infr .spectra of dust samples colleen asbestos was not expected) were 1 from kaolinitc or other mineral used critically; its vatue is lik. continuously monitored, when t a.. 4/6--* &000 1506 eu t>pr>Tvnr'tT- tsv V. L. Smith j__ i 3 S3 .ween J-5-3-2 I ! . EE3 deiermirution. ' Determination of ehrysolile in airborne asbestos 669 All samples to be analysed were received as deposits on 4-7 cm dia. "Millipore" fillers. These were ashed nt 450X for ~ I hr, during which process the material of the filter and any carbonaceous mailer present in the sample (which may reduce the transmission of the final disc) were oxidised or volatilized. Under these conditions decomposition of chrysolite is barely detectable, and no correction to the calibration graph was considered necessary. In the most careful work, however, it would be preferable to construct the calibration graph from standard samples heated in the same way. The residue in the crucible was incorporated in a potassium bromide disc and the amount of chrysolite present determined from the infra-red spectrum with the aid of the data set out in Fie. 2. The use of a microdisc, where a small rectangular lamina of KBr is pressed at the centre of a cardboard former, was also examined. Since the material was concentrated into an area roughly the same size as ihc beam, a considerable increase in sensitivity resulted; unfortunately difficulties arose in pre paring and calibrating such discs, and they were not adopted in routine analyses. Nevertheless, careful use of a microdisc offers the possibility of lowering the limit of satisfactory measurement to ~ 10 pg. APPLICATION This method has been used successfully for short-term sampling at workshop sites in this Laboratory. A certain amount of field work has also been carried out using, as far as possible, the standard volumetric instrument employed in the National Survey of Air Pollution in the United Kingdom, with the substitution of Millipore paper for the normal 5Whatman No. 1 paper. Filter papers were changed every 2 or days when operating for long periods. Short-term, high-volume sampling was also carried out at two sites-- a car park with a foundation of chrysotile waste and a refuse tip used for dumping asbestos waste. - Where long period sampling was carried out, in no case was chrysotile found above the limit of detection of the technique. This meant that the airborne concentration was below a value of 0 05 pg nr \ A few chrysotile fibres were found on the Millipore papers by examination under an electron microscope; the majority were around 0-3 pm in length. During short-term sampling at the sites mentioned above, chrysotile was only found in measurable quantities on two occasions and id both instances the value was about 1 pg nr*. ,, . .. t. .V:VW " CONCLUSION^* .. Amounts of chrysotile in the range 20-700 pg may be determined by this procedure. The method combines a low limit of detection with speed and simplicity, but is non specific; other serpentine minerals of related structure (e.g. kaolinite) show very similar absorption bands at 2-7 pm and their presence can invalidate any chrysotile .... determination based onthe infra-red absorption in this region. However, in this work, aamples collected from 12 industrial and other environments (where ` asbestos was not expected) were examined, and it was found that absorption at 2'7 pm from kaolinite or other mineral matter was rare. Nevertheless, this technique must be used critically; its value is likely to be greatest in environments which are to be continuously monitored, when the extent of likely interference can be established by a ret* *;V*' V./;?'.* V !&$***# v.';hr.*?;:, .->* K iR'TsrK5'!-' "! op om irmov mo ^ r uv 5 'i' ;*V - * %'**'"*.?* ^ .tfcja{ V* *L' ,,.? f .14 II; . i'' ' ' :.*' ;*.*/ ' . .. . . ^ *1,~!r~ * '--'i ; i 7' `* *-*'3' - Tij^V1: ^`Vt\r'i ^r ' ;y` v cr r 670 J. A. Gadsden, J. Parker and W. L. Smith preliminary investigation (using perhaps X-ray diffraction techniques). If such inter ference is found lo be negligible, subsequent routine measurement may be conducted with comparative ease by the technique described here; periodic tests for the presence of interfering material will, however, still be desirable. In all circumstances, however the method gives a valuable upper limit to the amount of chrysotile present in a sample. REFERENCES GooDiitAD K. and Martindale R. W. (1969) The determination ofamosite and chrysotile in air- home dusts by an X-ray diffraction method. Analyst 94, 985-98S. H.M. Factory Inspectorate (1967) Problems Arising from the Use of Asbestos. H.M.S.O., London. Martin A. E. (1966) lyfro-rtJ Instrumentation and Techniques. Elsevier, Amsterdam. 4tmt>spheric Environment Pergamon Pr SOURCE TEf Michael J. Pilat, Department of Civil Engineer (First received 8 Decet Abstract--The source lest cascade it bution of particles in stacks and d inserted inside the duct or stack ( problems. The new source lest case: bution of particles emitted from a K a fluidized bed sewage sludge inciner. cell. nomenclature C Cunningham correction factor i * particle diameter . i/J0 *= particle diameter collected with f> diameter of jet (hole in impactc Af v molecular weight of gas N > number of jets per impactor sta P -- gas pressure Q ~ gas volumetric flow rate throug! Rej * Reynolds number of jet j T -- gas temperature ' " V, * velocity of gas in jet ' Creek symbols ,4 -- mean free path of gas molecules !r gas viscosity - yVfriiSe 'i - 3.14159 ' -' >, >3 density or particle 4 = inertial impaction parameter it0 -= inertial impaction parameter at f i. Tiie size distributions of aerosol p: to: ., ' | (1) design new particulate air po :t (2) evaluate the performance of : and (3) characterize the aerosol emis `^Sa^^Jnfortunately a satisfactory techi t emission sources has not been a\ size measuring system include iso losses and vapor condensation, rci cost and ability to determine the ac can be inserted inside a duct or stac Mcnts. fly operating the impactor achieved with a minimum of wall L St00 2506 PRODUCED BY FORD Atmospheric Environment Pcrgamoo Press 1970. Vol. 4, pp. 667-670. Printed in Great Britain. DETERMINATION OF CHRYSOTILE IN AIRBORNE ASBESTOS BY AN INFRA-RED SPECTROMETRIC TECHNIQUE ' V* J. A. Gadsden, J. Parker and W. L. Smith Warren Sprint Laboratory, Ministry of Technology, Stevenage, Hens., U.K. (First received 1 June 1970 and in finalform 10 Aufust 1970) Abstract--A new method of determining chrysolite in airborne asbestos using infra red absorption at 2-72 is described. The technique is rapid, simple and allows detection of chrysolite down to about 20 ><g in the sample, provided that the terpentine minerals of related structure (c.g. Xaotinite) are absent. INTRODUCTION Increasing attention is now being paid to the health hazards arising from the in halation of airborne asbestos (H.M. Factory Inspectorate, 1968), and in conse quence of this, improved methods for the determination of chrysotilc and other asbestos minerals in airborne dusts are of wide interest. Recently Goodiiead and Martindale (1968) have reported an X-ray diffraction technique which possesses a number of advantages, but which needs about 30 mg of sample. In this note we describe an i.r. spectrometric method used in this Laboratory for*the determination of cbrysotile. The technique is rapid, simple and allows detection of chrysotilc down to about 20 pg in the sample. The method suffers from the disadvantage of being non specific within the serpentine class of minerals. In the absence of other serpentine minerals e.g. kaolinite, as was usually the case, the method is specific for chrysotilc asbestos, the form of asbestos most used commercially. EXPERIMENTAL TECHNIQUE Chrysotilc in common with other serpentine minerals possesses a sharp i.r. absorp tion band at 2-72 pm which is associated with the stretching vibration of the lattice hydroxyl groups present in the layer silicate structure. The band is fairly well separated from the broad absorption arising from the free or weakly adsorbed water molecules present in most solid samples (sec Fig. 1). The analogous bands in the amphibole asbestos minerals (amosite, crocidolite, etc.) are considerably weaker and are not suitable as the basis for an analytical technique. . In this work potassium bromide discs containing known amounts of chrysotile in the range 0-04-0-65 mg were prepared by the standard procedure (see, for example, Martin, 1966). Values of extinction \og.iol0ll, where /0 and 1 are the incident and emergent intensities of radiation respectively, measured at the peak of the 2-72 pm band, were determined from spectra recorded on a Grubb-Parsons "Spectromaster'' i.r. spectrometer, and were found to be proportional to the mass of chrysotilc present in the disc (Fig. 2). The sensitivity of the method is such that at the lowest levels of chrysotile content (<100 pg) difficulties arose in preparing standard discs containing such small amounts of material; however, the calibration graph is sufficiently linear to allow a reasonable extrapolation, and indicates a lower limit of detection of ~ 20pg. 667 t 8000 6383 #///* PRODUCED BY FORD M9ki At l'------ I 668 ). A. Caudm, 3. Parkir and W. L. Snn Detcn All samples to be analyst filters. These were ashed at ` filter and any carbonaceou J transmission of the final di | decomposition of chrysotile j graph was considered nece I preferable to construct the j same way. The residue in tl j and the amount of chrysotil ! aid of the data set out in f ! lamina of KBr is pressed ; Since the material was cone . considerable increase in se | paring and calibrating sue Nevertheless, careful use ol satisfactory measurement t< Fio. 1. Infra-red spectrum of chrysotile between 2-5-J-2 ^m. Fig. 2. Calibration craph for chrysotile determination. This method has been us in this Laboratory. A certain amount of fieh ! the standard volumetric in; in the United Kingdom, ; Whatman No. 1 paper. Fil for long periods. Sbort-terr a car park with a foundat asbestos waste. Where long period samp the limit of detection of t' was below a value of 0-05 / papers by examination un pm in length. During short-term sam i found in measurable quan , about 1 fig m'J. I i 1 Amounts of chrysotile ir The method combines a lc i specific; other serpentine j similar absorption bands: | determination based on th 1 spectra of dust samples c . asbestos was not expected' from kaolinite or other mi ; used critically; its value continuously monitored, v i tOG,0U0 /U *000 0364 j ' PRODUCED BY FObn 670 J. A. Gamdek, J. Parke* and W. L. Smith ' preliminary investigation (using perhaps X-ray diffraction techniques). If such inter ference is found to be negligible, subsequent routine measurement may be conducted with comparative ease by the technique described here; periodic tests for the presence of interfering material wilt, however, still be desirable. In all circumstances, however, the method gives a valuable upper limit to the amount of chrysotile present in a sample. REFERENCES Goodhead K. and Martindale R. W. (1969) The determination of amosite and chrysotile in air borne dusts by an X-ray diffraction method. Analyst 94, 985-988. H.M. Factory 1 nsrectorati (1967) Problems Arising from the Use of Asbestos. H.M.S.O., London. Martin A. E. (1966) Infro-red Instrumentation and Techniques. Elsevier, Amsterdam. Atmospheric Environment Pergamon P SOURCE TE Michael J. Pilat, Department of Civil Engine (first received 8 Dec Abstract--The source test cascade bution of particles in stacks and inserted inside the duct or suck problems. The new source test ca bution of particles emitted from a a fluidired bed sewage sludge incin cell. Nomenclature ; C -- Cunningham correction facie ! d * particle diameter d,e - particle diameter collected w j D diameter of jet (hole in imps t M -- molecular weight of gas N -- number of jets per impactor I P -- gas pressure | Q m gas volumetric flow rate thre j ftej -- Reynolds number of jet T -- |jas temperature I V, - velocity of gas in jet I Creek symbols i A - mean free path of gas motec ! ii -- gas viscosity j - 3.14159 i p, " density of particle i yl > inertial impaction parameter I ylo " inertial impaction parameter i V The size distributions of aeroso to: (1) design new particulate ai: (2) evaluate the performance and (3) characterize the aerosol t Unfortunately a satisfactory at emission sources has not ber siie measuring system include ' losses and vapor condensation ' cost and ability to determine tl . can be inserted inside a duct or ' merits. By operating the imoa achieved with a minimum ; i 8000 0386 PRODUCED BY FORD Atmospheric Enrironmem Pcrgamon Press J971. Vo). 5, p. 565. Primed in Croat Britain. DISCUSSIONS DETERMINATION OF CHRYSOTILE IN AIRBORNE ASBESTOS BY AN INFRA-RED SPECTROGRAPH 1C TECHNIQUE* We agree with the authors' conclusion that the technique would be valuable mostly in monitoring air for asbestos where possible interferences would be negligible. Also we agree that the detectability of the method makes it applicable primarily to point source emission areas. Ambient air concentra tions of asbestos generally range from 0.001 to 1 pg m*'. We feel it would be useful to comment on possible use of the silicate absorption in the 9-10 pm, wavelength region which may be much stronger than the OH absorption at 2.72 pm and thus may provide for better measurements at low concentrations of chrysolite. It would be useful if the known or possible interferences were listed. Finally we feel that with a longer collection period and with a separation of interfering materials, this technique might have a wider application and possibly be applicable to the low concentrations found in ambient air. Also useful could be comments of the extent to which the method differentiates chrysolite from its thermally degraded form, Forsterite, and from other silica particulates found in air such as quart:, talc, and mica. A Senior Research Chemist, Em'ironmenlal and Materials Characterisation Division, Randle Memorial Institute, Columbus, Ohio 43201. , R. E. Herrs CPtNor.a ' AUTHOR'S REPLY We should like to make the following reply to the points which Mr. HerrEUiNCBa has raised: We consider the silicate absorption at 9-10 pm to be unsuitable for the purposes of this analysis because ' (i) The absorption occurs in the infra-red spectra of most dust samples and is hence very unspecific (ii) the band is broad and ill-defined and (iii) is frequently overlapped by other broad and ill-defined absorptions. If the use of the method becomes widespread a list of interfering substances would be useful, but it would be preferable to wait until further experience has revealed the commonest sources of inter ference. In the meantime, workers may find it useful to remember that interfering bands are given by minerals which are related to chrysolite (e.g. those of the serpentine family). We believe, but have not checked experimentally, that the ashing technique employed here would free forsterite and quartz from adsorbed water molecules and since these minerals possess no struc tural OH groups, chrysotile is readily distinguishable from them. However adsorbed, i.e. lattice, hydroxyl groups aro not easily eliminated in amorphous silicas and do give rise to absorption bands it ~2'7 pm. Talc and mica are likely to interfere and their absence should be confirmed before regarding the method as being suitable. Finally, the length of the collecting period is limited by the amount of opaque material which can be tolerated in the final potassium bromide disc. Physical and Chemical Services Division, Warren Sprint Laboratory, Slevenafe. J. A. Gadsden, J. Parke* and W. L. Smith * J. A. Gadsden, J. Parker and W. L. Smith, Atmospheric Etwiromenl 4, 667-470 (1970). 565 9' T'V'V BOOG 03B7 ' PRODUCED BY FORD