The well-known methods for the determination of serum iron, which are based on colour reactions with bathophenanthroline disulfonate, Ferrozine® or Chromazurol B, require — even on a microscale — sample amounts between 0.1 and 1.0 nil of serum (1,2,3). These sample volumes are too large for paediatric purposes. Reduction of sample size is possible in flame atomic absorption spectrophotometry us...