Quality control and reference materials in speciation analysis

This contribution describes the need and some strategies for a rigid qualit y control in speciation analysis. Firstly, the term "chemical speciation" i s defined and differentiated from experimental concepts now called "operati onally defined speciation" or "functionally defined speciation". The need f or quality control in speciation is given by the big number of sources of e rrors during sampling, sample preparation, separation and detection. Errors such as stability problems, contaminations or losses, spectral interferenc es etc. are discussed. On the other hand, several concepts for problem solu tions are described. One of these solutions is the use of certified referen ce 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 strateg ies are necessary for each pan of the analytical speciation procedure. Seve ral examples of such procedures are given and discussed.