QUALITY CRITERIA FOR THE ISOTOPE-DILUTION METHOD WITH HRGC MS/

The isotope dilution method is characterized by the use of appropiatel y labelled standard compounds in conjunction with mass spectrometry co upled to chromatographic systems. Although the isotope dilution method seems to be a simple procedure, some quality criteria for sample prep aration, measurement and quantification have to be considered. Further more, archiving and documentation of analysis data as well as the use of reference materials to validate the analysis method are important w ith regard to European standard regulations for quality assurance. In view of this background and the increasing application tendency to env ironmental problems, essential quality critera for the isotope dilutio n method are presented and discussed, with special respect to sample e xtraction, separation performance and sensitivity. Also the quantifica tion procedures are summarized.