Classical and rapid methods of analysis

Abstract

Chapters 2–7 are mainly concerned with the analysis of silicate rocks by schemes in which the sample is first taken up into solution. Although at first sight this appears to be a rather arbitrary classification, in many laboratories a progressive evolution has occurred in techniques based on rock solution analysis. The earliest schemes of analysis, now known as ‘classical’ techniques, were based principally on the use of the analytical balance in determining individual components. Such procedures, therefore, involved extensive chemical manipulations so that elements could be precipitated and assayed individually from starting samples. During the 1950s the ‘classical’ techniques evolved into ‘rapid’ schemes of analysis. These still relied on detailed solution chemistry but made use of flame photometry, spectrophotometry and complexometric titrations to eliminate some of the more time-consuming chemical manipulations. Rapid techniques have themselves now largely been superseded by more modern instrumental procedures: first atomic absorption spectrometry, followed by inductively coupled plasma-atomic emission spectrometry and now, in a few selected laboratories, inductively coupled plasma-mass spectrometry. All have one common requirement, that of taking the sample up into solution before analysis. In this chapter the techniques for dissolving rocks will first be considered and then the evolution of classical and rapid schemes of analysis.