Identification of chemical substances in analytical measurements

Abstract

 Characteristic features of identification procedures of chemical substances are described and the metrological requirements for identification are discussed. The procedures are considered to be rigorous enough, if quantitative criteria such as the measure of similarity between physicochemical properties or spectra of the unknown substance and reference materials are used. Identification involves expert opinion which is of prime importance in the analysis of samples of unknown composition. The reliability of substance recognition can be increased by selecting highly qualified personnel, establishing a good information supply, using an on-line combination of separation and detection instruments such as chromatography-spectrometry and estimating the probability of identification. Standard conditions for reliable identification including quantitative criteria are examined using gas chromatography-mass spectrometry as an example.