NYC-WTC_000226903

NYC 9/11 Public Portal Document

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Pace Analytical Serrices, Inc. 1700 Elm Street, Suite.200 'ace Analytical’ W Minneapolis, MN 55414 Phone: 612.607.1700 www.pacelabs.coin REPORT OF: CHEMICAL ANALYSES Fax: 612.607.6444

ji PROJECT: PCDD/PCDF ANALYSES DATE: January 9, 2002

PAGE: 3 REPORT NO: 01-1052682

PCDD/PCDF Analyses TCdnt.)

M The mass spectrometer was operated in the electron impact ionization mode at a mass resolution ■’ of 10,000-1 T,00O (M/AM, 10 percent valley definition). This resolution is sufficient to resolve most interfenehces, such as PCBs, thus providing the highest level of confidence that the detected p levels oTpPCDD/PCDF were not false positives resulting from interferences. Typical operating parameters for the HRGC/HRMS analyses are summarized in Table 2. ra ' ■ ■ ■■

HYThe data were acquired by selected-ion-recording (SIR) using groups of ion masses similar to those described in USEPA Method 8290. The five groups corresponded to the tetrachlorinated through I3 octachlorinated congener classes. Each group contained two ion masses for the PCDDs, two ion ri masses for the PCDFs, the corresponding ion masses from the two isotopically labeled internal standards, and the ion mass characteristic of the polychlorinated diphenylether (PCDE) which, if present, could cause false responses in the dibenzofuran channels. fl Each group of ion masses also contained a lock mass which was used by the data system to „/1 automatically correct the mass focus of the instrument. The data system determined the centroid of the lock mass during each data acquisition cycle and corrected the mass focus of the analyte and internal standard ion masses to assure that the centers of the mass peaks were being monitored. ,2 The criteria used to judge positive responses for a PCDD/PCDF isomer included:

Simultaneous response at both ion masses of the PCDD or PCDF Signal-to-noise ratio equal to or greater than 2.5:1.0 for both ion masses Chlorine isotope ratio within 15% of the theoretical value . Chromatographic retention time within -t-/- 2 seconds of the expected retention time Chromatographic retention times within elution windows determined from analyses of standard mixtures Absence of simultaneous response in the PCDF and PCDPE ion traces

S' A list of the exact ion masses monitored for the determination of PCDD/PCDF isomers and the PCDE interferences is presented in Table 3. Also included are the theoretical chlorine isotope ratios , for the ten congener classes.

y 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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