NYC-WTC_000202123

NYC 9/11 Public Portal Document

Pace Analytical Services, Inc. 1700 Elm Street, Suite 200 weAnalyticar ■ Minneapolis, MN 55414 Phone: 612.607.1700 www.pacelabs.com REPORT OF: CHEMICAL ANALYSES Fax: 612.607.6444

PROJECT: PCDD/PCDF ANALYSES DATE: April 5, 2002

PAGE: 5 REPORT NO: 02-1055016

PCDD/PCDF Quantification and Calculations (Cont.) Each pair of ion mass peaks in the selected-ion-current chromatograms was evaluated manually to determine if it met the criteria for a PCDD or PCDF isomer. Areas of all peaks exhibiting correct ion ratios, haying retention times within the correct windows, and having areas corresponding to concentrations in the range covered by the initial calibration were then summed for calculations of total congener concentrations. The toxic equivalence of each sample was calculated using the factors listed in Table 5.

A limit of detection (LOD) based on producing a signal that is 2.5 times the noise level, was calculated for each undetected 2,3,7,8-substituted isomer of any tetra through octa chlorinated congener class. The noise heights used to calculate the detection limits were measured at the retention time of the specific isomer. The formula used for calculating the LOD is:

Hn X Qis X 2.5 LOD = His X W X Rf where:

' LOD = Single isomer limit of detection .. Hn = Sum of noise heights at native isomer retention time Qis = Quantity of labeled internal standard His = Sum of peak heights for labeled internal standard W = Sample amount Rf = Response factor

The recovery of the 2,3,7,S-TCDD-^CU enrichment efficiency standard and each ^’’Gi2-labeled internal standard, relative to either 1,2,3,4-TCDO-i^Ci2 or 1,2,3,7,8,9-HxCDD-’5Ci2, was calculated using the following equation:

Ais X Qrs x 100% %R = Rfr X Ars x Qis where:

%R - Percent recovery of labeled internal standard Ais Sum of integrated areas of labeled internal standard Qrs Quantity of recovery standard Ars Sum of integrated areas of recovery standard Rfr Response factor of the specific labeled internal standard relative to the recovery standard Qis Quantity of the labeled internal standard congener added to the sample

REPORT OF LABORATORY ANALYSIS This report shall not be reproduced, except in full, without the written consent of Pace Analytical Services, Inc.

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NYC-WTC_000202129