Toward a revival of classical analysis

Among the analytical methods used to determine chemical composition, there are two special methods based on reaction chemistry. These are gravimetry and titrimetry, and taken together they are called classical analysis. They are special because they lead directly to independent values of chemical quantities expressed in SI units. Gravimetry and titrimetry can be performed in such a way that their operation is completely understood, and all significant sources of error in the measurement process can be evaluated and expressed in SI units together with a complete uncertainty budget. Such chemical measurements are metrologically valid and stand alone. They have no need to be compared with a reference material of the quantity being measured and therefore are called definitive or primary methods. In this paper the basic equations and terms of gravimetry and titrimetry are discussed, together with detailed examples of each. This is followed by a discussion of the errors associated with gravimetry and titrimetry, and instrumental techniques that can be used for evaluating these errors. There is also a discussion of the uncertainties associated with both systematic and random errors in gravimetry and titrimetry. The paper is underpinned by historical sketches of several important issues and scientists connected with the development of classical analysis. A case is made for a revival of the use of classical analysis in chemical metrology, together with some suggestions as to how such a revival might be implemented.