Page 22 - Modern Analytical Chemistry

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Chapter 1 Introduction 5

You will come across numerous examples of qualitative and quantitative meth-
ods in this text, most of which are routine examples of chemical analysis. It is im-
portant to remember, however, that nonroutine problems prompted analytical
chemists to develop these methods. Whenever possible, we will try to place these
methods in their appropriate historical context. In addition, examples of current re-
search problems in analytical chemistry are scattered throughout the text.
The next time you are in the library, look through a recent issue of an analyti-
cally oriented journal, such as Analytical Chemistry. Focus on the titles and abstracts
of the research articles. Although you will not recognize all the terms and methods,
you will begin to answer for yourself the question “What is analytical chemistry”?

1B The Analytical Perspective

Having noted that each field of chemistry brings a unique perspective to the study
of chemistry, we now ask a second deceptively simple question. What is the “analyt-
ical perspective”? Many analytical chemists describe this perspective as an analytical
7
approach to solving problems. Although there are probably as many descriptions
of the analytical approach as there are analytical chemists, it is convenient for our
purposes to treat it as a five-step process:

1. Identify and define the problem.
2. Design the experimental procedure.
3. Conduct an experiment, and gather data.
4. Analyze the experimental data.
5. Propose a solution to the problem.
Figure 1.3 shows an outline of the analytical approach along with some im-
portant considerations at each step. Three general features of this approach de-
serve attention. First, steps 1 and 5 provide opportunities for analytical chemists
to collaborate with individuals outside the realm of analytical chemistry. In fact,
many problems on which analytical chemists work originate in other fields. Sec-
ond, the analytical approach is not linear, but incorporates a “feedback loop”
consisting of steps 2, 3, and 4, in which the outcome of one step may cause a
reevaluation of the other two steps. Finally, the solution to one problem often
suggests a new problem.
Analytical chemistry begins with a problem, examples of which include evalu-
ating the amount of dust and soil ingested by children as an indicator of environ-
mental exposure to particulate based pollutants, resolving contradictory evidence
regarding the toxicity of perfluoro polymers during combustion, or developing
rapid and sensitive detectors for chemical warfare agents.* At this point the analyti-
cal approach involves a collaboration between the analytical chemist and the indi-
viduals responsible for the problem. Together they decide what information is
needed. It is also necessary for the analytical chemist to understand how the prob-
lem relates to broader research goals. The type of information needed and the prob-
lem’s context are essential to designing an appropriate experimental procedure.
Designing an experimental procedure involves selecting an appropriate method
of analysis based on established criteria, such as accuracy, precision, sensitivity, and
detection limit; the urgency with which results are needed; the cost of a single analy-
sis; the number of samples to be analyzed; and the amount of sample available for

*These examples are taken from a series of articles, entitled the “Analytical Approach,” which has appeared as a regular
feature in the journal Analytical Chemistry since 1974.