NYC-WTC_000202123

NYC 9/11 Public Portal Document

Pace Analytical Services, Inc. 1700 Elm Street, Suite 200 ^aceAnalyticar Minneapolis, MN 55414 Phone: 612.607.1700 www.pacelab5.coni REPORT OF: CHEMICAL ANALYSES Fax: 612.607.6444

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

PAGE: 7 REPORT NO: 02-1055016

RESULTS

The results from the analyses are presented in the following:

Appendix A - Documentation Appendix B - PCDD/PCDF Analysis Results

DISCUSSION

The recoveries of the isotopically-labeled PGDD/PCDF internal standards in the sample extracts ranged from 50-120%. All of the internal standard recoveries for field samples were within the target limits for this method. Also, since the quantifications of the native 2,3,7,8-substituted isomers were based on isotope dilution, the data were automatically corrected for variation in recovery and accurate values were obtained.

A laboratory method blank was prepared and analyzed with each sample batch as part of our routine quality control procedures. The results, found at the beginning of Appendix B, show Blank 1523 to contain a trace level of 2,3,7,8-TCDF. This level was below the calibration range of the method. The samples were found not to contain this isomer at the reporting limits. This indicates that the sample processing procedures did not significantly impact the results of the analyses.

Laboratory spike samples were also prepared with each sample batch by extracting clean wipes that had been fortified with native standard materials. The results, found at the end of Appendix B, show that the spiked native compounds were recovered at 68-121%. These results indicate a „ generally high degree of accuracy for these samples. It should be noted that one isomer in spike 1537 was recovered slightly below the target range for this method. The affected point is flagged "P" on the data summary sheet.

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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