Various media, solid, liquid and gaseous, have been used for analytical
purposes and it is difficult to decide which medium causes most problems
in analytical chemistry. The answer to this question depends on the detailed
knowledge of the medium used. Since analytical chemistry began, studies
have been carried out mainly in aqueous media, so it is not surprising that
the majority of data have been accumulated on reactions and interactions
taking place in this medium. Fewer data are available on solid and gaseous
media, in which analytical determinations are carried out also. In respect
of the practical point of view of analytical chemists, the disturbing effects
relating to the media can be eliminated by controlling the conditions of
measurement experimentally. Empirical methods give possibilities for the determination of well-defined components under well-defined conditions.
The problems of researchers who intend to develop a new analytical method
are completely different, because it is possible only if the properties of the
medium and its reactions are well-known. Here the effect of the medium
cannot be overcome by speaking about matrix effect, which does not say
anything about details.