Low-Level VOCs Sampling
All water samples must be collected before chlorination or any other form of treatment (true for all environmental tracers analyzed by the Reston CFC Lab). Four replicate water samples are collected at each site without contact with the atmosphere in 125-mL glass bottles with aluminum-foil lined caps. The procedure is the same as the collection procedure for CFCs. Refrigeration-grade copper or nylon tubing should be used to establish a closed path from the well discharge to the bottom of the bottle, which is submerged in an overflowing container. The bottles are capped under water without headspace. The samples are not preserved and are stored at room temperature preferably upside down. After collection, a bubble may form in the bottle. This is normal.