Environmental Services Program

The Organic Semi-Volatiles Laboratory

A semi-volatile organic compound (SVOC) is one of two major classes of organic compounds which include: pesticides, PCBs, polynuclear aromatics, plasticizers, wood preservatives, and other pollutants. These compounds may be found deposited on or mixed in with vegetation, soil, or water. They might even be found as abandoned hazardous waste mixed in with other man-made chemicals.

Semi-volatiles could encompass thousands of organic chemicals. However, the field has been narrowed to more commonly known environmental contaminants that are potentially adverse to public safety. In other words, the focus is on those chemicals we know can be harmful to people, animals, or the environment.

The basis of the SVOC class is the fact that they are not as easily gaseous at room temperature (as are the volatiles). This makes semi-volatile analyses more difficult because they must first undergo preparation by extraction. SVOC extractions actually involve volatile organics used as their solvents. Consequently, segregating the two classes is clearly important in order to prevent accidental contamination of our volatile samples. Because the SVOC class is so diverse it is further subdivided to allow the best and most accurate methods be used for their analyses. For a complete list see CAS analytical capabilities.

Laboratory Separatory FunnelA separatory funnel is used for liquid-liquid extractions.  The water sample (blue) and solvent (red) are shaken together.  The heavier solvent is allowed to settle out, with extracted contaminates, to the bottom layer where it can be drained away.

Once extracted, an SVOC sample will move on for separation by chromatography. The method used will either be capillary gas chromatography or high performance liquid chromatography. The specific identity and concentration of all separated compounds are subsequently determined by a detector.