Air monitoring TEM analysis, 51 Harrison, Nov 2001

NYC 9/11 Public Portal Document

TRANSMISSION ELECTRON MICROSCOPY (TEM) METHODOLOGY

technique, which focuses an electron beam Transmission Electron Microscopy (TEM) is a beam microscope column (under a vacuum). As the onto a thin sample mounted in the resulting from varying density of the sample is transmits through the sample, an image collected on either samples for TEM analysis can be projected onto a fluorescent screen. Air direct transfer polycarbonate filters and are prepared using mixed cellulose ester or preparation allows for the transfer of a carbon- techniques (as per EPA regulations). Direct on to a the filter material (with embedded fibers and particulates, etc.) right coated replica of intermediate Indirect transfer techniques require an copper grid suitable for TEM analysis. may break-up fiber bundles, resulting in an increased fiber amount. step that for the preparation and analysis of air samples by electron Several methods exist ry and non-mandatory microscopy. Most signif;cant are the mandaAHERARegulations). These methods arettoobe as appendices to 40 CFR 763, Subpart E ( projects. air samples on school abatement used for analysis of final clearance represented by each fiber analytical sensitivity is the airborne asbestos concentration collected the The determined air electron s counted under the fivty be no microscope~e{hod requires that the analytcal elns proportion of the filter examined. This . greater than 0.005 structures/cc. register but their sow indicators Sampling pumps must be calibrated and ank are' to be taken by removing the cap for +is no more than 10 liters/min. Two (2) field is be crried with each samle set. blank more than 30 seconds. A sealed IedaThese samples are spbmtted tohthe representative cassette is not to be opened in thef eriod f for quality control purposes. The sampling houl be broPght tooa laboratory liters of air. Thesamples darelate~ time to conform at least a volume of 1200 certified laboratory for the analysis.

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