Air monitoring TEM analysis, 51 Harrison, Nov 2001

NYC 9/11 Public Portal Document

(TEM) TRANSMISSION ELECTRON MICROSCOPY METHODOLOGY

technique, which focuses an electron beam Transmission Electron Microscopy (TEM) is a beam sample mounted in the microscope column (under a vacuum). As the onto a thin sample is resulting from varying density of the transmits through the sample, an image collected on either fluorescent screen. Air samples for TEM analysis can be projected onto a epared ect transfer ester or polycarbona ilters e an are mixed cellulose aration allowrsPor the trangsferrof a techniques (as per EPA regulations). Direct p p fibers and particulates, etc.) right on to a coated replica of the filter material (with embedded intermediate suitable for TEM analysis. Indirect transfer techniques require an copper grid resulting in an increased fiber amount. step that may break-up fiber bundles, electron methods exist for the preparation and analysis of air samples by Several ndatory TEM mandatory microscopy. Most significant are the AHERA Regulations). These methodssare oobe e

as appendices to 40 CFR 763, Subpart E projects. air samples on school.abatement used for analysis of final clearance er analytical sensitivity is the airborne as stos concentration The betemined by the air volume collected and, counted under the electron microscope. It sensitivity be no method requires that the analytical proportion of the filter examined. This greater than 0.005 structures/cc. register more than 1 but and their flow indicators must Sampling pumps must be calibrated blanks are to be taken by removing the cap Th±is for not than 10 liters/min. Two (2) field no more carried le set. sealed blank i more than 30 seconds. A These samples are submitted to the representative cassette is not to be opened in thebfiled ucted for The sampling houl be laboratory for quality control purposes. liters of air. The samples dare late bropght to a time to conform at least a volume of 1200 certified laboratory for the analysis.

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