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Air, Water, & Hazardous Waste Sampling, Analysis, & Consultation Central State Certified Hazardous Waste, Chemistry, & Bacteriology Laboratories Coast 141 Suburban Road, Suite C-4 6483—D Calle Real Analytical San Luis Obispo, Ca 93401 Goleta, CA 93117 Services J Fax (805) 543-2685 Fax (805) 976-4386 (805) 543-2553 (805) 964-7838 AMBIENT AIR MONITORING The sampling techniques we recommend for air monitoring projects for trace organics employ Tedlor bogs, specially possivated steel containers, solvent desorbable cartridges and thermally desorbable cartridges. The analytical methods employed to determine the very i.ow 'levels of trace organics collected by the techniques are described in the paragraphs which follow. ANALYTICAL TECHNIQUES The preferred analytical technique employs a freezeout technique to separate the trace organics in ambient air from major air components such as oxygen and nitrogen. Dr. Hovlicek, Mr. Hutchison and Ms. Richards of the project team have considerable prior experience in the application of this technique to air samples collected in Tedlor bogs and possivated steel containers such as were employed in connection with our recent studies at Cosmalio Resources and at another active hazardous waste disposal site in the Central Valley. A schematic diagram of this apparatus is presented in Figure 1 (Hoyt, 1885). An evacuated reservoir of known volume is used to pull air, 3Tam the sample bog or possivated steel container through the sample fresTootrt loop which is immersed in liquid argon. A vocuum gouge attachet' to the reservoir is used to measure the pressure drop caused by the tronzfer of air from the sample container to the reservoir. Since the volume of the reservoir is known, the amount of air pulled through the freezeout loop can be calculated. Since the freezeout loop is at liquid argon temperature, oxygen and nitrogen cannot condense. Because the loop is packed with tiny inert glass beads, trace organic constituents have a large -contact surface upon which to condense. Since atmospheric water vapor will also condense and since water can cause problem with the subsequent analysis, a Nafion dryer is placed between the sample and the freezeout loop. This inert materal is selectively permeable to water which is then swept away by a flow of dry nitrogen on the outside of the Nafion tube. Since the trace organics being determined have almost no tendency to permeate the Nafion, they pass through at their original concantrations. Once the desired volume of air has been collected, the six port valve is rotated and the freezeout loop is heated. This action isolates the freezeout loop from the vacuum reservior and from the sample container while admitting a flow of carrier gas which then sweeps the revolatilized organics from the loop to a capillary trap. r]