Polar compounds, petroleum concentrations

Nonaqueous Liquid Wastes Protocol. Nonaqueous liquid wastes were defined to include samples that range from water-soluble organic liquids to immiscible oils. Only a limited amount of data are available on the applicability of this protocol (Figure 4) to compounds other than oils or petroleum products. This medium differs from other environmental media because mutagenic materials are often concentrated in organic liquids. Therefore, this protocol incorporates dilution steps rather than the concentration techniques used in the other media protocols. This protocol is also unique because of the opportunity to test neat samples or samples diluted with DMSO rather than sample components isolated with an absorbent or extracted with a solvent. For this reason, samples treated with this protocol should contain polar compounds and/or volatile compounds that would be lost when the other protocols are used. 

On the other hand, gas chromatographic methods may overestimate the concentration of total petroleum hydrocarbons in a sample due to the detection of nonpetroleum compounds. In addition, cleanup steps do not separate petroleum hydrocarbons perfectly from biogenic material such as plant oils and waxes, which are sometimes extracted from vegetation-rich soil. Silica gel cleanup may help to remove this interference but may also remove some polar hydrocarbons. 

Separating a whole sample of a coal liquid or shale oil into classes poses special problems since these materials contain high concentrations of heteroatomic species compared with natural petroleums. Many of these compounds are quite polar and can cause emulsification, precipitation, and may even react to produce artifactual compounds at some stage during a separation procedure. Many liquid chromatographic techniques have been useful in class separations and analyses of petroleums. More often, these have been applied to particular analytical scale operations with fossil-derived liquids. The most common applications are for aromatic-aliphatic and molecular weight types of separations. 

---