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11 The capillary trap is itself immersed in a cryogenic fluid. This is necessary since the volume of the freezeout loop is large when compared with the flow through the analyzing column. This second freezing out serves to focus the materials collected on the original freezeout loop into a very sharp bond which can be readily accommodated by and rapidly transfered to the remainder of the capillary column within the gas chromatograph. Capillary columns are preferred because they not only provide better separation but can be positioned directly within the source of the mass spectrometer. Since there is no need for a separator to remove excess carrier gas (as would be necessary for packed columns), all of the material originally present in the sample is introduced directly into the source of the mass spectrometer. Since this introduction of separated sample components takes place over a very short time interval, more sample is presented to the analytical detector per unit time than would otherwise be possible. This factor contributes significantly to the low detection limits which we are able to reach. CARTRIDGE SAMPLES The analytical system employed for the analysis of cartridge samples is much like that used for bag and canister samples. In this case, the freezeout loop is replaced by a thermal desorption mini -furnace (actually a conventional purge -and -trap apparatus). The furnace is then heated while being swept by an inert carrier gas. Since the volume of carrier gas required to sweep the desorbed organics from the cartridge is large compared to the flow through the analytical column, a capillary trap is again necessary. Because water can still cause problems, a Nafion dryer is placed between the mini -furnace and the capillary trap. ' ADVANTAGES OF PASSIVATED STEEL CONTAINERS A major reservation regarding the use of steel containers for the collection of ambient air samples has been the belief that sensitive compounds would be destroyed by contact with metallic surfaces within the container. Fortunately for CCAS, the development of passivation techniques designed to render the inner surfaces of stainless steel containers sufficiently advanced stage of development so that these specialized containers are commercially available. CCAS has nearly 100 such containers in stock. We are now using these containers in Santo Barbara County for the collection of samples to be analyzed for corbonyl sulfide, carbon disulfide, hydrocarbons and volatile priority pollutants. We are also using electropolished stainless steel containers for compliance analyses in and around domestic landfills.