Preparation of environmental samples for mineral analysis

The term "environmental protection" currently represents a set of human activities whose ultimate aim should be to prevent its degradation or, at the very least, maintain it in its current state. In this case, the environment should not only be considered from the human point of view, but also as a global ecosystem. If we look at long-term problems, we have to realize that most of the phenomena involved are chemical in nature, and that the pathways to identifying and eliminating them lie precisely in this discipline. Chemical analysis therefore plays a very important role: only data obtained under appropriate conditions and interpreted in a reasoned manner can guarantee the success of subsequent interventions. In the past, we have witnessed situations where the link between the various stages of environmental protection studies underestimated analytical control; even today, we cannot say that the use of chemical analysis has reached its rightful level in this field. What we need to talk about is analytical strategy, represented by the following points:

• rigorous definition of the problem to be addressed ;

• problem-oriented sample selection (sampling) ;

• proper sample preparation ;

• quantitative measurement of the elements associated with the initial problem ;

• validation and evaluation of results ;

• interpretation of results and conclusion.

From the point of view of finding the initial situation, it is necessary to take as a basis a set of analyses characterized by a high number of element determinations in various samples, in the knowledge that their major element composition (matrix) is unknown and/or variable. It should be remembered here that this matrix is precisely responsible for the greater or lesser difficulty of the analysis, due to the effects it can impose during sample preparation or when measuring the element in question (analyte). According to this criterion, environmental samples can be classified according to the analytical difficulty caused by the presence of a complex matrix and/or very low concentrations:

• drinking water, surface water, rainwater, wastewater ;

• soil, sediment, sludge, suspended solids in water and atmospheric dust;

• animal tissue, excrement, insects ;

• plant tissues (particularly difficult due to the variable presence of silica); sea water (low concentrations to be determined) and biological fluids (blood, urine, milk: complex and/or highly variable matrices);

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