VOST (Volatile Organic Sampling Train)
The train consists of 2-3 sorbent tubes (Tenax and petroleum based charcoal - Method 0030) or (Tenax, Tenax and Anasorb 747 - Method 0031) and a condensate. A VOST train is used to capture the organics during stationary source testing. A wide range of compounds can be determined using a VOST sampling train. The preparation and use of the train is precisely documented in Methods 0030, 0031 and 8260/5041.
TO-17 Multi-bed Carbotrap 300 Tubes
These are generally stainless steel tubes packed with Carbopack C (a weak sorbent), Carbopack B (a medium sorbent) and Carbosieve SIII (a strong sorbent). This multibed tube can be used for a broad range of target compounds: Vinyl chloride to pyrene has been validated using these tubes.
TO-11A Tubes
These are silica tubes which have been coated with dinitrophenylhyrazine (DNPH). The coated silica is generally placed in a Teflon tube. As air is pulled through the tube, carbonyl compounds are derivatized and remain in the tube.
Amberlite XAD-2 Resin Trap
This polymeric resin is used to collect semi-volatile compounds from a variety of sources. It is commonly used in conjunction with a glass fiber filter. The resin must be cleaned prior to use using organic solvents and a vacuum oven. Target compounds are removed using soxhlet extraction followed by a solvent exchange and concentration step. XAD-2 is specified in many source testing methods as well as TO-13A.
PUF Cartridge
Polyurethane foam in conjunction with a glass fiber filter is used to collect organochlorine pesticides and polychlorinated biphenyls. The foam is cleaned, prior to use, using soxhlet extraction and a vacuum. The foam is initially white and yellows when exposed to direct sunlight. Semi-volatile compounds are adsorbed on the surface of the foam; they are removed using soxhlet extraction. Often a filter is used to collect the particulates for TO-4A. Excessive exposure to organic solvents degrades the foam. PUF is specified in TO-4A, TO-10A and TO-13A.
XAD-2/PUF Cartridge
This combination is often used to collect ambient air semi-volatiles. The resin is placed between PUF plugs in a glass cartridge. The organic compounds are adsorbed on the surface of either the PUF (if halogenated) or the XAD. Often a filter is used to collect the particulates. The filter is extracted along with the PUF and XAD. This combination trap is specified in TO-13A.
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