S.O.P. No. MLD 032 - Determination of Non-Methane Organic Compounds
                                      in Ambient Air by Gas Chromatography using
                                      Dual Capillary Columns and Flame Ionization Detection

SCOPE

This is a gas chromatographic (GC) method for the determination of volatile organic hydrocarbons, C2 through C10, from ambient air samples.  The method is developed from and based upon EPA Document 600-8-9/215.

 SUMMARY OF METHOD

This document describes the method for analysis of non-methane organic compounds (NMOC) in ambient air.  It involves the cryogenic pre-concentration of volatile organic compounds (VOCs), of which many are involved in photochemical formation of ozone in atmosphere.  VOCs are defined as aliphatic and aromatic compounds having a vapor pressure greater than 0.10 Torr at 250C and 760 mm Hg.  This method documents the analytical procedure for the measurement of subset of the VOCs list covered by Compendium Method TO-14(A) and addresses 56 recommended target VOC compounds (range of C2 through C12,) that are listed in the USEPA Photochemical Assessment Monitoring Stations (PAMS) air quality surveillence program (40 CFR Part 58, Subpart E).  Method MLD032 is a modified version of USEPA Compendium Method Toxic Organics TO-14(A) and is applicable to most conditions encountered in the sampling of whole air samples into SUMMATM passivated stainless steel canisters, and also addresses water removal by NafionTM dryer before analysis.  This method applies to ambient concentrations of VOCs above 1.0 ppb C (parts per billion Carbon).