Newer microscopic techniques have the potential to enhance our view of surface contamination in situ and provide more comprehensive information about contaminants and surface quality. However, direct observation of the surface may not answer all questions, and it is not always feasible.
Cleaning and extraction have many similarities; however, the goals and potential “tripping points” are different. For cleaning, we are not necessarily concerned about reactivity with the cleaning agent, as long as the soil is effectively removed from the surface and kept from the surface. Analysis of the extract may involve determining levels of particulates, or of non-volatile residue. Also after extraction, we may want to do speciation, to identify or at least categorize the soil. This means that the extraction chemical should not react or change the chemical nature of the soil.
Getting the most from testing requires careful planning and understanding of both the benefits and limitations of the analytical technique. This understanding goes beyond extraction. The bottom line is that next time you plan to spend money on a test, take the time to learn about it; and get to know your laboratory analyst.