NYC-WTC_000199812

NYC 9/11 Public Portal Document

3.0 PCDDs, PCDFs, AND PCBs

3.1 Collection

3.1.1 Surface Wipe

Isopropanol-moistened 3-inch by 3-inch cotton gauze pads were used to collect surface­ wipe samples from table tops and other furniture. The gauze pad was held with a gloved hand (non-linear polyethylene-type glove). The surface was wiped using successive swaths first in one direction, then in a second direction perpendicular to the first. Multiple gauze pads were used as necessary depending on the surface dust loading. The gauze pad sample was then placed in a clean glass sample container equipped with a Teflon-lined lid. The sample area was measured and recorded.

3.1.2 Surface Dust

A new stiff bristle toothbrush was used to collect dust samples from furniture such as table tops and other furniture with a hard surface. The dust was swept into a pile and collected using a scoop constructed of paper. The dust was then placed in a clean 50-ml polyethylene centrifuge tube with a screw-cap lid. The sample area was measured and recorded.

3.1.3 Bulk Dust

Bulk dust samples were collected from exterior surfaces (including a window ledge and a roof top) with heavy deposits of dust. The dust was placed in either a clean zip-lock plastic bag or 50-ml plastic centrifuge tube.

3.2 Analysis

3.2.1 Surface Wipe

The samples were prepared and analyzed to determine the presence of tetra- through octa-chlorinated dibenzo-p-dioxins and dibenzofurans and the respective 2,3,7,8-substituted isomers using high-resolution gas chromatography/high-resolution mass spectroscopy

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CITY_21MC100_006730095

NYC-WTC_000199825