Quality criteria for the isotope dilution method with HRGC/MS.

The isotope dilution method is characterized by the use of appropiately labelled standard compounds in conjunction with mass spectrometry coupled to chromatographic systems. Although the isotope dilution method seems to be a simple procedure, some quality criteria for sample preparation, measurement and quantification have to be considered. Furthermore, archiving and documentation of analysis data as well as the use of reference materials to validate the analysis method are important with regard to European standard regulations for quality assurance. In view of this background and the increasing application tendency to environmental problems, essential quality critera for the isotope dilution method are presented and discussed, with special respect to sample extraction, separation performance and sensitivity. Also the quantification procedures are summarized.