Carpet mastic asbestos analysis results letter, December 2002

NYC 9/11 Public Portal Document

EMSLNYCNOBCHTFIELDSOP 200.0 Revison 1 February, 2002 3.0 SAMPLE ANALYSIS

Sample Preparation Acceptance 1. • More than 50% of-the grid must be covered by-the replica. 2. Grids must have at least 50% intact grid openings. 3. Grids must not have more than 10% opaque area due to incomplete filter dissolution. 4. Total Grid openings must have <50% overlapping of folded replica film 5. At least 20 grid openings with <5% holes and <5% opaque area due to incomplete filter dissolution. 6. Grid openings analyzed must not have rips or overlapping folds.

Bulk (Chatfield & NOB) 1. Remove the first sample grid from the box and insert it into the TEM. At a magnification of 300 to 500x, orient an intact grid opening on the middle of the screen. 2. Increase magnification to 3,000 or 19,000x taking care to remain in the chose grid opening. 3. Randomly scan the sample choosing fields with a moderate loading of debris. 4. Estimate the percent asbestos vs. the percent debris on each field. Ignore any fields that do not contain debris. Cover several areas of the filter in case of a non- homogeneous sample.

To better estimate the true percent, tilt the sample in order • to visualize a three-dimensional picture as a two-dimensional image may be misleading causing false high asbestos percents. 5. Calculate the average asbestos.concentration from all of the fields analyzed and record the estimated concenteration (for NYNOB) or the estimated range (for Chatfield analysis). 6:- If a fibrous structure has been located, check its morphology against.the morphologies for each asbestos type. If morphology is consistent with asbestiform fibers, proceed to EDX analysis. 7;;— Obtain an EDXof-the Semple by-fcfllowing-the-pro-cedures-outlined-in- ENERGY— DISPERSIVE X-RAY ANALYSIS SOP and compare it to the spectra for the asbestos types. Record the information on the sample worksheet. If the chemistry is consistent with one of the asbestiform minerals, proceed to Diffraction analysis. 8. Obtain a diffraction pattern for the sample by following the procedures outlined in DIFFRACTION ANALYSIS SOP. Record diffraction information on the sample worksheet. 9. If the morphology, diffraction, and 'EDX information match that of an asbestos type, then record the structure as asbestos. 10. For asbestos structures, there is no need to note fiber, bundle, matrix, or cluster. 11. Working magnification is 3,000 and 10,000 to 19,000x. 12. Fiber criteria - Estimate range percent of asbestos 13. Sizing of fibers - Not recorded • 14. Required EDX • - The first five structures and every tenth there after • 15. Required diffraction patterns

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