DOH/DEP asbestos fact sheet draft, 105 Duane Street

NYC 9/11 Public Portal Document 12/11/2001 17:06 FAX 212 363 8306 ATC l l 009

') D 5755 12.1.1 Remove a section (a plug) from any quadrant of not be used. Carbon rods (7.40) used for evaporators shall be the simple and blank filters_ Sections can be removed from sharpened with a carbon rod sharpener to a neck of about 4 the filters using a 7 mm cork borer (7.32). The cork borer mm in length and l mm in diameter. The rods are installed must be wet wiped after each time a section is removed. in the evaporator in such a manner that the points are 12.1.2 Place the filter section (particle side up) on a clean approximately 100 to 120 mm from the surface of the microscope slide. Affix the filter section to the slide with a microscope slide held in the rotating device. Summed page reinforcement (7.43), or other suitable means. 12.4.2 Place the glass slide holding the filters on the Label the slide with a Blass scribing tool or permanent rotation device, and evacuate the evaporator chamber to a marker (7.10). vacuum of at least 13 MPa. Perform the evaporation in very 12.1.3 Prepare a fusing dish from a glass peni dish (7.37) short burro, separated by 3 to 4 s to allow the electrodes to and a metal screen bridge (7.38) with a pad of five to six cooL An alternate method of evaporation is by using a slow ashlea paper filters (7.42) and place in the bottom of the continuous applied current. An experienced analyst can petri dish (4). Place the screen bridge on top of the pad and judge the thickness of the carbon film to be applied. Conduct saturate the filter pads with acetone. Place the slide on top of tests on unused filters fast. If the carbon film is too thin, the bridge in the petri dish and cover the dish. Wait large particles will be lost from the TEM specimen, and there approximately 5 min for the sample filter to rase and dear. will be few complete and undamaged grid openings on the 12.2 Dfinethy(formanrfde.Acetie Acid Method specimen. 12.2.1 Place a drop of clearing solution that consists of 12.4,2.1 If the coating is too thick, it will lead to a TEM 35 % dimethylformamide (DMF), 15 % glacial acetic acid, image that is lacking in contrast, arid the ability to obtain and 50 % Type 11 water (v/v) on a clean microscope slide. electron diffraction patterns will be compromised. The Gauge the amount used so that the clearing solution just carbon film shall be as thin as possible and still remain intact saturates the filter section. on most of the grid openings of the TEM specimen. 12.2.2 Carefully lay the filter segment, sample surface 12.5 Preparation of the Jaffe Washer—The precise design upward, on top of the solution. Bring the filter and solution of the Jaffa washer is not considered important, so any one of together at an angle of about 20' to help exclude air bubbles. the published designs may be used (7, S). One such washer Remove any excess clearing solution. Place the slide in an oven or on a hot plate, in a fume hood, at 65 to 704'C for 10 consists of a simple stainless steel bridge contained in a glass min. Petri dish. 12.3 Plasma etching of the collapsed filter is requirecL 12.5.I Place several pieces of lens tissue (7.41) on the 12.3.1 The microscope slide to which the collapsed filter stainless steel bridge. The pieces of lens tissue shall be large pietas are attached is placed in a plasma asher (7.27). enough to completely drape over the bridge and into the Because plasma ashers vary greatly in their performance, solvent In a fume hood, fill the petri dish with acetone (or both from unit to unit and between different positions in the DMF) until the height of the solvent is brought up to contact asher chamber, it is difficult to specify the exact conditions the underside of the metal bridge as illustrated in Fig, 2. that must be used. Insufficient etching will result in a failure 12.6 Placing the Specimens into the Jafe Washer: to expose embedded fibers, and too much etching may result 12.6.1 Place the TEM grids (7.39) shiny side up on a piece in the loss of particles from the filter surface. To determine of lens tissue or filter paper so that individual grids can be the optimum time for asking, place an unused 25 mm easily picked up with tweeters diameter MCE filter in the center of a glass microscope slide. 12.6.2 Prepare three grids from each sample. Position the slide approximately in the center of the asher 12.6.2.1 Using a curved scalpel blade (7.20). excise at least chamber. Close the ebumber and evacuate to a ptestute of two square (3 mm by 3 mm) pieces of the carbon-coated approximately 40 Pa. while admitting oxygen to the chamber MCE filter from the glass slide. at a rate of 8 to 20 cm3/min. Adjust the tuning of the system 12.6.2.2 Place the square filter piece carbonside up on so that the intensity of the plasma is maximized. Determine top of a TEM specimen grid. the time required for complete oxidation of the filter. Adjust 12.6.2.3 Place the whole assembly ( /grid) on the the system parameters to achieve complete oxidation of the saturated lens tisme'in the Jaffe washer. filter in a period of approximately 15 min. For etching of collapsed filters, use these operating parameters for a period Elsotran slsronespe of 8 mm. For additional information on calibration, see the Brass pint disk sps.hnens $tatrwsa steal mesh USEPA Asbrnas-Contafidng Materials in Schools (4) or [loci lahl MST/NVLAP Program Handbook for Airborne Asbestos Analysis (6) documents. 12.3.2 Place the glass slide containing the collapsed filters into the low-temperature plasma usher, and etch the filter. 12.4 Carbon Coating of the collapsed and etched filters is required. 12.4.1 Carbon coating must be performed with a high- vacuum coating unit (7.4), capable of less than 10—` torr (13 MPa) prasu re. Units that are based on evaporation of Lens Tint carbon filaments in a vacuum generated only by an oil rotary pump have not been evaluated for this application and shall PIG. 2 . llrar~pla of Design of Solvent Washer (Jeff. Washer)

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