VOLATILE ORGANIC COMPOUNDS IN VARIOUS SA

2.1.1 Water samples - A 40-mL VOA vial is filled with water. The water sample can be fixed by addition of a chemical preservative to the vial. When the vial is headspace free, it is capped. At the laboratory, that vial is sub-sampled into a headspace vial. A matrix modifier is added to the headspace vial, along with internal standards and surrogates, and the headspace vial is then capped. The matrix modifier acts to partition the volatile organic compounds into the headspace. 2.1.2 Soil samples - at least 2 g of a soil sample are placed into a crimp-seal or screwtop glass headspace vial, along with a matrix modifier and any chemical preservative, at time of sampling. For soils, the matrix modifier also acts as a chemical preservative, so it must be added to the soil during sampling. The headspace vial is then sealed. Surrogates and internal standards can be added to the vial upon sampling, or at the laboratory by injection.