ANALVTICAL CHEMISTRV EDITORIAL
September 1971, Vol. 43, No. 11 Editor: HERBERT A. LAITINEN
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Analytical Chemistry in Environmental Science Ill. The Importance of Sampling N ENVIRONMENTAL SCIENCE,even
more than in analysis generally, the truth of the old homily, “no analysis is better than the sample on which i t is based,” should be emphasized. There are two basic considerations involved. First, the samples may be extremely diverse in character, and the materials of interest are often present a t great dilution in situations of chemical, physical, or biological instability. The operation of procuring a representative sample from a dynamic, heterogenous system can present quite a challenge. The storage of the sample, to prevent loss of trace constituents or contamination by interaction of the sample with the walls of the container or with the atmosphere, needs consideration. Segregation of the sample prior to analysis may occur. Of course, all of these problems are inherent to analysis in general and are by no means unique to environmental science. It is just that they tend to be exacerbated by the nature of the problem. The second consideration is the use to be made of analytical data, often by nonscientists. Improper inferences can be drawn, not necessarily through conscious efforts to distort data to strengthen a n argument, but also through ignorance or lack of information about the sampling procedure. Proper experimental design involves drawing a representative sample from a population appropriate to the problem, and recognizing the nature of that population in applying the data. For example, it is clear that entirely different sampling procedures would be involved in the two problems: ( a ) What is the total mercury content of the fish in Lake Michigan, or (b) What is the mercury content of the edible portions of Coho salmon from the same lake? Data obtained to answer one of these questions would give no valid information about the other; yet, improper interpretations can be innocently made in the absence of sampling information. Another common error of interpretation is an improper averaging of analytical data without proper attention being paid to weighting. Indeed, in environmental science, the individual peak readings are often of more significance than average data. The analytical chemist should play his role from the beginning of the measurement problem in collaborating in the experimental design, t o the end, in helping with the interpretation of the data. I n this way, he can make his full professional contribution and help avoid the pitfalls of drawing erroneous conclusions from experimental data.
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