Trace Environmental Quantitative Analysis TEQA

The latter half of the twentieth century has taken the United States and other developed nations from a postindustrial era to a new age that some people refer to as a period that is rich in information technology. We enter the new millenium as a nation in transition, and people want to know to what extent chemical substances have contaminated the environment. In the United States and other postindustrial nations, manufacturing and related human activities that were so dominant in both the nineteenth and twentieth centuries appear to have left their mark on the environment. This book provides the tools necessary to begin to answer the contamination questions by introducing the reader to that part of the science of contemporary analytical chemistry that is devoted to environmental monitoring, testing, and interpretation. All of these aspects are conveniently summarized in the term Trace Environmental Quantitative Analysis (TEQA). 

The academic discipline of environmental chemistry is a relatively recent development. Environmental chemistry can be defined as a systematic study of the nature of matter that exists in the air, water, soil, and biomass. This definition could be extended to the plant and animal domains where 

In its broadest sense, environmental chemistry might be considered to include the chemistry of everything outside of the synthetic chemist s flask The moment that a chemical substance is released to the environment, its physico-chemical properties may have an enormous impact on ecological systems, including humans. Researchers have identified 51 synthetic chemicals that disrupt the endocrine system. Hormone disrupters include some of the 209 polychlorinated biphenyls (PCBs), and some of the 75 dioxins and 135 furans that have a myriad of documented effects (1). The latter half of the twentieth century has witnessed more synthetic chemical production than any other period in world history. Between 1940 and 1982, the production of synthetic chemicals increased about 350 times. Billions of pounds of synthetic materials were released into the environment during this period. United States production of carbon-based synthetic chemicals topped 435 billion pounds in 1992 or 1600 pounds per capita (2). 

A more recent controversy has arisen around the apparent leaching of bisphenol A from various sources of plastics that are in widespread use among consumers. A dialog appeared recently on this issue and this difference of opinion serves to point out the necessity of measuring bisphenol A in various plastic wraps, containers, and so forth, particularly plastic materials that come in contact with food and beverages (5). These concerns point out the need to find ways to measure this chemical in plastic matrices. How 

Recently, the EPA has released its plan for testing 15,000 chemicals for their potential to disrupt hormone systems in humans and wildlife. These chemicals were chosen because they are produced in volumes greater than 10,000 pounds per year (6). 

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Trace environmental quantitative analysis (TEQA) has developed a terminology of its own and this appendix consists of a glossary of terms used in not only trace analysis but also in the regulatory realm. The following sources were used to develop this glossary. 

Trace environmental quantitative analysis (TEQA) requires that a specific QC document be written and available. This appendix further elaborates on QC as first introduced in Chapter 2 and first written by the author in support of the National Institutes of Environmental Health Sciences (NIEHS) Basic Superfund Research Center Analytical Core. 

Trace environmental quantitative analysis (TEQA) utilizes various determinative teehniques (Chapter 4) in combination with various sample prep techniques (Chapter 3). In this appendix, one specific trace analysis using static headspace sampling automatically coupled to capillary gas chromatography with element specific detection is described. LSQUARES is a computer program developed by the author in BASIC and is used in the quantitative analysis discussed below. The actual program written in GWBASIC is also listed after illustrating its use in TEQA. 

The determination of xq for a given detector response, yo> is, of course, the most important outcome of trace quantitative analysis. Xq, together with an estimate of its degree of uncertainty, represents the ultimate goal of trace quantitative analysis, that is, it answers the question How much of analyte i is present and how reliable is this number in a given environmental sample For TEQA, it is usually unlikely that the population mean for this interpolated value /a(xo) can ever be known and that the standard deviation in this population mean, [Pg.40]

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