Environmental Engineering Reference
In-Depth Information
require simple instruments. More complex analysis involving extraction, concentration,
and instrumental analysis are done in the commercial laboratory. In any analytical
procedure sample preparation is an essential first step that is often followed by extraction
and finally by analysis. Analytical procedures may be standard wet chemical methods or
more complex instrumental methods. Commonly the instruments used fall into two
groups—those based on spectroscopy and those based on chromatography. In some cases
a combination of spectrophotometric and chromatographic methods will be used in the
analysis. Once all the analysis is completed the data are checked and a final report is
prepared and presented to the client.
The final data and resultant report can be no better than the original simple submitted
for analysis, and this also applies to all steps of the analytical procedure. If care is not
taken at every step—sampling, transport, storage, and during the analytical processes—
errors will be compounded and the resultant data will be flawed. The ultimate result is
that the data do not accurately reflect the true nature of the field being tested.
QUESTIONS
1. What are the limiting factors for the determination of sampling and testing methods?
2. Insulated ice chests are often used to transport samples from the field to the
laboratory. What must the ice chest or cooler contain in addition to the samples? What
two purposes does the ice serve?
3. What is one of the most important factors in obtaining a representative sample in the
field? What two factors go along with this point?
4. Name three common methods used for sample preparation.
5. What laws are fundamental as applied to an analytical procedure?
6. What are the two types of quantitative analyses and three groups of instrumental
techniques? Name each and give a short description of how they work.
7. What does PM stand for? What is this person's role?
8. When the concentration of an analyte of interest is far beyond the range of the
instrument or method, what must be done to analyze it? How can analyzing samples
containing too much of an analyte adversely affect the subsequent analytical procedures?
9. What is the sampling logic tree and how is it used in sampling and sample analysis?
10. What is an extraction reference or surrogate and how is it used in the sample
analysis process?
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