Quality control and reference materials in speciation analysis

Abstract

This contribution describes the need and some strategies for a rigid quality control in speciation analysis. Firstly, the term “chemical speciation” is defined and differentiated from experimental concepts now called “operationally defined speciation” or “functionally defined speciation”. The need for quality control in speciation is given by the big number of sources of errors during sampling, sample preparation, separation and detection. Errors such as stability problems, contaminations or losses, spectral interferences etc. are discussed. On the other hand, several concepts for problem solutions are described. One of these solutions is the use of certified reference materials (CRM). Unfortunately, species-certified CRM are only available for few matrices and few elements, e.g. mercury in fish or sediments, lead in solutions and urban dust etc. Therefore special quality control strategies are necessary for each part of the analytical speciation procedure. Several examples of such procedures are given and discussed.