Trace Organic Analysis

Tools of The Trade--Separations and Detections

by William C. Brumley (February 2003)

Trace organic analysis occupies a unique position in the many disciplines of the environmental sciences. Its ability to identify and report how much of a substance occurs in a given context is invaluable. The basic measurements that are common in this field are widely known via the official U.S. EPA numbered methods [(e.g., SW-846 8270 and Method 625 (Water)]. The techniques used to carry out analytical investigations depend on our ability to separate mixtures into individual compounds and detect them. Separations and detections thus form the backbone of applied analytical tools that in turn provide the information sought.

However, chemical analysis shares with other fields of scientific research an unfinished nature because our knowledge is never complete. Continuous development of techniques and instrumentation play a central role in the advancement and improvement to the measurements that are needed to protect human health and the environment.

Consider the ecosystem depicted in an illustration also shown here showing the multitude of ways in which human activities and one group of consumer chemicals can interact directly with the environment. Human behavior is intimately involved with the ecosystem, and largely determines the routes and types of man-made chemicals that enter the environment. Examples include treated sewage waste, industrial waste, and agricultural run-off. The introduction of new chemicals into commerce demands new methodology to monitor for them and may pose new risks of exposure for man and the flora and fauna of the ecosystem that may need to be assessed. Methodology must adjust to accommodate the changing nature of the exposure and conform to new information relative to levels of concern (for example, lower levels needed) or adjust to altered economic constraints (less expensive approaches needed). This methodology derives, in part, from the field of trace organic analysis.

Man-made chemicals (anthropogenic xenobiotics) are only a small fraction of the total millieu of substances that compose an ecosystem. Other compounds include the natural foods we eat, semiochemicals (chemical communicators), various minerals, gases in the air, biochemicals of life, and metabolic products from plants and animals. See discussion and figures regarding "The Universe of Organic Chemicals" at: http://www.epa.gov/nerlesd1/chemistry/pharma/critical.htm.

In the pages to follow, we will be defining and illustrating the various pieces that make up the field of trace organic analysis. In this endeavor we will find that certain techniques and instrumental approaches assume a fundamental importance in carrying out the analyses. Among these techniques are general areas called separations and another called detections. In the separations area gas chromatography has been the preeminent tool. In the detection area, mass spectrometry has been central to the advancement of methods used by U.S. EPA and other regulatory agencies. This in turn has spawned a subdivision of mass spectrometry termed regulatory mass spectrometry, and we will develop that aspect as well. For extensive additional information regarding the numerous aspects of analytical chemistry (including mass spectrometry), see the web links at: http://www.epa.gov/nerlesd1/chemistry/ppcp/relevant.htm#Chemistrylinks; in particular, note the links at the end of this web page for animations of various chemistry instruments and procedures.

To navigate this site, use the links on the bottom of the page. The FAQ are the gateway to a number of illustrations and discussions that deal with specific aspects. Here is where the main development of the theme is carried out. Publications and abstracts refer to work that I have authored or coauthored. The links will help you find other sites that contain much useful information relevant to trace organic analysis or its application. Emerging areas suggests newly defined areas that are being explored in part by trace organic analysis.

Any feedback is always seriously considered.

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