Total petroleum hydrocarbons screening measures

The screening measures for total petroleum hydrocarbons screening are done differently in various states, regions, and individual laboratories. In fact, the data that are reported as total petroleum hydrocarbons are so variable that much caution should be exercised when attempting to compare or interpret the data. As analytical methods evolve in response to environmental needs, the definition of total petroleum hydrocarbons may become more closely related to reality rather than to the respective analytical method. 

Thus, the methods for measurement of total petroleum hydrocarbons (Table 8.1) (see also Chapter 7) provide adequate screening information but do not provide sufficient information on the extent of the contamination and product type. 

Furthermore, since different combinations of petroleum hydrocarbons typically contribute to total petroleum hydrocarbons at different sites, the fate characteristics are also typically different at different sites, even if the total petroleum hydrocarbons concentration is the same. Different methods used to generate total petroleum hydrocarbon concentrations, or similar simple screening measures of petroleum contamination, all produce very different result. 

Analysis performed in the field is faster and more economical than analysis done in a laboratory. As analytical techniques are constantly improving and lighter and more portable equipment is being developed, more analytical work can be carried out directly in the field. Test methods are now available for measuring physical properties of oil such as viscosity, density, and even flash point in the field. Test kits have also been developed that can measure total petroleum hydrocarbons directly in the field. While these test kits are less accurate than laboratory methods, they are a rapid screening tool that minimizes laboratory analysis and may provide adequate data for making response decisions. 

---