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Perchlorates in the Laboratory for Analytical/Physical Chemistry

Recently recognized problem of perchlorate in the environment is a cause of growing interest in production, uses and properties of perchloric acid and its salts. In this article, properties of such chemicals, important from the viewpoint of an analytical/physical chemist, are reviewed. The topics of interest include: solubility, complex formation, surface activity and redox reactions, all in aqueous solutions. The behavior of perchlorates in nonaqueous media, their influence on solubility of other substances, their quantification at trace level and application of hot perchloric acid in wet ashing of environmental samples are also discussed. Under laboratory conditions, well known properties of such salts (high solubility, poor surface activity, stability under reducing condition and inertness against complex formation) make them applicable for different purposes, with a possible “extrapolation” to the treatment of polluted waters. More and more exceptions, i.e. cases in which perchlorate ion does not behave in accordance with the mentioned scheme could be found. They mainly include its participation in redox reactions with solid or dissolved metals whereas surface activity and complex formation are less pronounced. Further investigations of such and similar examples seem interesting and could be important when different solid materials, instead of mercury, are introduced in preparation of electrodes for voltammetric measurements.

solubility, hydration, water activity, surface activity, complex formation, precipitation, redox processes, trace analysis

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