MONITORING AND LABORATORY DIVISION
STANDARD OPERATING PROCEDURE
PARALLEL STUDY OF DATA FROM AMBIENT AIR SAMPLES ANALYZED BY METHODS MLD052, MLD057, AND MLD058 FOR 1,3-BUTADIENE, AROMATIC, AND HALOGENATED COMPOUNDS

PURPOSE

The Organic Laboratory Section has implemented a change in the procedure used for the analysis of aromatic and halogenated Toxic Air Contaminants (TACs) in ambient air. The new procedure, MLD058, titled "Standard Operating Procedure for the Analysis of Aromatic and Halogenated Hydrocarbons in Ambient Air Using Summa Canister Sampling and Gas Chromatographic/Mass Spectrometric Analysis", was implemented for Southern TAC monitoring sites on February 1, 2001, and for all TAC monitoring sites on May 1, 2001. The previous procedures were: MLD057 - "Standard Operating Procedure for the Determination of 1,3-Butadiene and Benzene in Ambient Air by Capillary Column Gas Chromatography with Photoionization Detector", and MLD052 - "Standard Operating Procedure for the Determination of Volatile Aromatic and Halogenated Compounds in Ambient Air by Gas Chromatography Using Capillary Column with Photoionization and Electron Capture Detectors." The purpose of this parallel study is to compare results obtained from the analysis of ambient air samples by the two gas chromatography detector oriented methods, MLD057 and MLD052, and the new GC Mass Spectral Detector oriented method, MLD058. If warranted, procedures for temporarily offsetting any discontinuity in the historical data set caused by changing analytical Methods will be discussed.