Asbestos analysis methods for carpeting samples, 1993

NYC 9/11 Public Portal Document

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of the surfactant aerosol OT or a 0.002% solution of the surfactant 200 ml glass medical specimen bottle. All visible traces of the methyl cellulose in particle-free water. The beaker is placed in an sample are rinsed into the specimen bottle with a plastic squin bottle ultrasonic bath for 30 minuies. The carpel piece is removed and of filtered water. Tliis procedure is repeated two additional times rinsed into the beaker with lOOmillilitersofparticle-free water. The for a total of three washings. Next, the nozzle i.s rinsed two or three entire suspension (200 milliliters.) is then shaken vigorously by times into the specimen bottle. Typically, the total amount of water handtodispersethcparticlcsandlhenallowedtosilforiwominutes used in the rinse i.s approximately 70 to75 ml. The water level in to allow the den.ser panicles to sink and the light particles to float the specimen bottle i.s then carefully adjusted to 100 ml with to the top. At this lime, three measured aliquots ofdifferent volume.s pre tillered water. Tire pH of the water is adjusted to 3-4 using a 1.0% (u.suaiiy one (1). ten (10) rind fifty (.50) milliliters) arc extracted KCl :w!ution. The sample ceniainar is capped and ultrasonicated with disposable graduated pipettes 1/4 to 1/2 inch below the water for three minutes to make a uniform suspension. After two minutes surface in the beaker. The aliquot is mixed with particle-free waler of settling, a measured volume of suspension i.s extracted with a tomakc50niillililcrsandrilleredthrougha.0.22pmporesizemixed graduated pipette inserted halfway into the sample solution. Tlie cellulose ester filter or a 0.2 pm polycarbonate filter backed by an aliquot is mixed with particle-free water in ihc filter funnel and 0.45 pm pore size cellulose ester filter. If by visual observation, the filtered through a 0.22 pm pore size mixed cellulose ester filter initial beaker contains large non-asbeslos fibers (carpet material). backedbyanS.Opmporcsizecelluloseeslcrfiltcr.Thefiiterisdried iheeniirc suspension is passed through a coarse stainless steel mesh and prepared according to the AHERA air sample preparation screen. 'Hie filters are dried and prepared for TEM analysis procedure. A sample blank is prepared in an idemical way as the according to the NIOSH 7402 preparation procedure (cellulose sample, although no carpet segment is actually vacuumed. ester filter)'’ or the Yamaie. et al., procedure (polycarbonate filter).'* AileasttwoTEMgridsfromdiffcrentareasofthefiltcrareprcparcd AsbestOS Counting for each sample. After the three filtration.s are completed, the remaining suspension is transferred to a graduated cylinder and the In the transmission electron microscope, the number of each volume recorded. Tlii.s volume is added to the volumes of the type of asbesios structures, chrysotile or amphibole, is determined measured aliquots to obtain the total volume of the sample. Thi.s by examining a known area on the grid in term.s of a-numberof grid accounts for the variable amount of water absorbed in the carpet openings. Tire asbestos fibers are identified on the basis of during processing. A .sample blank is prepared in an identical way morphology; .selected area electron diffraction (SAEDi and/or a,s the sample, although no carpet segment i,s actually u.scd in the energy dispersive X-ray spectrometry (EDS), ultrasonic procedure. The samples arc counted following the EPA (Yamate) Provi- sional Method "or the AHERA counting rules. The choice of The Microvoc Technique counting method.s depends on the particular interest of the anal> st. TIte Yamale counting rules provide more information about the Samples which are collected by microvacuuming are sizes of structures found by the analyst than do the AHERA commonly referred to a.s microvac samples or .microvac dust counting rules. The amount of asbestos in a given sample is samples. They arc collected byvacuuminga lOOcm-areaforothcr e-xpressed as structures per square foot, structures per square known area) of carpet with a membrane filter air-sampling cassette ccniimetcr or structure.s per .square meter. The value is calculated and vacuum pump. TIic sampling assembly consists of a 25-mm using the following equation: diameter mi.xcd cellulose ester filter contained in a three-piece standard AHERA'-* air cassette with a one (1) inch piece of tubing attached to the face cap as a nozzle'”. Tlic end of the nozzle is cut EFA X 100.x NOSTR at 45 degrees. Tltc cassette is connected to a personal sampling —------------------------- = STRUCTURES /AREA OF pump with flexible tubing. The pump and cassette assembly are GO x GOA X SPL X V THE CARPET calibrated to 2 L/min. The 100-cm- area is vacuumed by moving the filter cassette nozzle across the carpet to agitate the carpet pile.. NOSTR = Number of asbestos structures counted in The carpel is vacuumed for approximately 30 seconds in one the analysis direction, then another 30 seconds in a direction 90 degrees to the first. Aficronc minute of vacuuming, the pump is turned off and the EFA = Effective filler area of Ihe final sampling filter cassette nozzle is plugged and the cassette is labeled. filler in square milliincicr.s In the laboratory, the unopened microvacuuming cassette.s are wet-wiped and then prepared for analysis under cletui room condi­ GO =s Number of grid openings analyzed tions. Tltc cassette.s and filters are rinsed out with particle-free water and rcfiltercd through a second filter which is used in the GOA = Average area of one TEM grid opening analysis. Tile original filter is washed during the sample prepara­ in square millimeters tion procedure but otherwise is not used in the preparation. Specifically, the plug from the nozzle of the cassette is SPL = Amount of carpet area sampled (in square feet removed and the cas.setie i.s filled with approximately 10 ml of prefiltcrcd water. The plug is replaced and the cassette is shaken or square centimeters) vigorously by hand fortwo to three seconds. The entire cap of the cassette is removed and the suspension poured into a pre-cleaned V = Volume of sample filtered

on Environmental QioitesTedmkol Supplement • Warth/April 1993

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