Challenges from speciation analysis for the development of biological reference materials.

Starting with explanations for the increasing demand for speciation analysis the need of appropriate certified reference materials is justified. Specific aspects of biological reference materials for speciation QA/QC are discussed from the point of view of the total analytical process. Examples of unwanted species transformations during analysis are given and critical analytical steps are highlighted. Unchanged biological materials as CRMs and appropriate pure standard compounds are indispensable for the further development of this analytical field.