The features of the physico-chemical background of analytical chemistry, as it was viewed during the first half of this century, is first described. The impact of the massive introduction of instrumentation and separation techniques is discussed, and the start of a change of analytical chemistry in the direction to become a science of measurement is signaled. The "third revolution" is defined as derived not only from automation of instruments, procedures and laboratories and from computerization, but also from the use of chemometrics, and from the increasing importance of the socio-chemical problems in which analytical scientists are involved. Chemometrics and physical chemistry now build up the unifying background of analytical chemistry, which was so much diversified by instrumentation into almost
independent subdisciplines. 33 references
