Forwarding WTC air monitoring scope for final review, Aug 2002

NYC 9/11 Public Portal Document

Environmental Protection Agency Pt. 763, Subpt. E, App. A Note: The person breaking the chain-of- f. Store the three grids to be measured in custody seal and Itemizing the contents as­ appropriately labeled grid holders or poly­ sumes responsibility for the shipment and ethylene capsules. signs documents accordingly. 5. Equipment. 4. Assign a laboratory number and sched­ a. Clean area. ule an analysis sequence. b. Tweezers. Fine-point tweezers for han­ 5. Manage all chaln-of-custody samples dling of Alters and TEM grids. within the laboratory such that their integ­ c. Scalpel Holder and Curved No. 10 Sur­ rity can be ensured and documented. gical Blades. d. Microscope slides. F. Sample Preparation e. Double-coated adhesive tape. f. Gummed page reinforcements. 1. Persormel not affiliated with the Abate­ g. Micro-plpet with disposal tips 10 to 100 ment Contractor shall be used to prepare gL variable volume. samples and conduct TEM analysis. Wet­ h. Vacuum coating unit with facilities for wipe the exterior of the cassettes to mini­ evaporation of carbon. Use of a liquid nitro­ mize contamination possibilities before tak­ gen cold trap above the diffusion pump will ing them to the clean sample preparation fa­ minimize the possibility of contamination of cility. the Alter surface by oil from the pumping 2. Perform sample preparation in a well- system. The vacuum-coating unit can also be equipped clean facility. used for deposition of a thin Alm of gold. Note: The clean area is required to have 1. Carbon rod electrodes. Spectrochemlcally the following minimum characteristics. The pure carbon rods are required for use in the area or hood must be capable of maintaining vacuum evaporator for carbon coating of Al­ a positive pressure with make-up air being ters. HEPA filtered. The cumulative analytical J. Carbon rod sharpener. This is used to blank concentration must average less than sharpen carbon rods to a neck. The use of 18 s/mm^ in an area of 0.057 s/mm^ (nominally necked carbon rods (or equivalent) allows 10 200-mesh grid openings) with no more than the carbon to be applied to the Alters with a one single preparation to exceed 53 s/mm^ for minimum of heating. that same area. k. Low-temperature plasma asher. This is 3. Preparation areas for air samples must used to etch the surface of collapsed mixed be separated from preparation areas for bulk cellulose ester (MCE) filters. The asher samples. Personnel must not prepare air should be supplied with oxygen, and should samples if they have previously been pre­ be modified as necessary to provide a throt­ paring bulk samples without performing ap­ tle or bleed valve to control the speed of the propriate personal hygiene procedures, l.e., vacuum to minimize disturbance of the Al­ clothing change, showering, etc, ter. Some early models of ashers admit air 4. Preparation. Direct preparation tech­ too rapidly, which may disturb particulates niques are required. The objective is to on the surface of the Alter during the etch­ produce an Intact carbon film containing the ing step. particulates from the filter surface which Is 1. Glass petrl dishes, 18 cm In diameter, 1 cm sufficiently clear for TEM analysis. Cur­ high. For prevention of excessive evaporation rently recommended direct preparation pro­ of solvent when these are in use, a good seal cedures for polycarbonate (PC) and mixed must be provided between the base and the cellulose ester (MCE) filters are described in lid. The seal can be improved by grinding the Unit III.F.7. and 8. Sample preparation is a base and lid together with an abrasive grind­ subject requiring additional research. Vari­ ing material, ation on those steps which do not sub­ m. Stainless steel mesh. stantively change the procedure, which im­ n. Lens tissue. prove filter clearing or which reduce con­ o. Copper 200-mesh TEM grids. 3 mm in di­ tamination problems in a laboratory are per­ ameter, or equivalent. mitted. p. Gold 200-mesh TEM grids, 3 mm in di­ ameter, or equivalent. a. Use only TEM grids that have had grid q. Condensation washer. opening areas measured according to direc­ r. Carbon-coated. 200-mesh TEM grids, or tions in Unit III.J. equivalent. b. Remove the inlet and outlet plugs prior s. Analytical balance. 0.1 mg sensitivity. to opening the cassette to minimize any t. Filter paper. 9 cm In diameter. pressure differential that may be present. u. Oven or slide warmer. Must be capable c. Examples of techniques used to prepare of maintaining a temperature of 65-70 °C. polycarbonate filters are described In Unit V. Polyurethane foam. 6 mm thickness. in.F.7. w. Gold wire for evaporation. d. Examples of techniques used to prepare 6. Reagents. mixed cellulose ester Alters are describe in a. General. A supply of ultra-clean. Aber- Unit in.F.8. free water must be available for washing of e. Prepare multiple grids for each sample. all components used in the analysis. Water

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NYC-WTC_000139304