Basic analytical chemistry: conventional gravimetric analysis

Abstract

Conventional gravimetry (also known as precipitation gravimetry) consists of a sequence of operations that aims to precipitate (separate) the substance of interest (the analyte) in the form of a poorly soluble compound, with known and well-defined stoichiometry. After its separation and drying, the precipitate is weighed on an analytical balance and, from its mass and stoichiometry, the concentration of the original analyte is quantitatively determined. It is a method of analysis in which the measured signal is the mass or mass change, and its application requires only the use of base units of the International System of Units (SI), such as the mass or the mole. Among the advantages of using this technique are its good reproducibility, associated with the simplicity of operational execution and the use of equipment commonly used in the laboratory. On the other hand, its main disadvantages lie in its execution time, which is generally very long and in the lack of sensitivity of the method, which makes it impractical for the determination of microconstituents in the sample. Despite being subject to accumulative errors, caused by possible execution failures in the various steps, operations, and manipulations necessary for its execution, the results obtained with the use of gravimetric methods are quite accurate, limited only by the detection limit of the analytical balance used in the procedure. It is the oldest quantitative analysis technique, and although it is not currently the most important analytical method, it is still used in specialized applications and in process standardization.