Establishing the fitness for purpose of mass spectrometric methods

This report is submitted by a working group sponsored by the ASMS Measurements and Standards Committee. The group responded to a 1998 opinion piece dealing with mass spectrometry in trace analysis (Bethem, R. A.; Boyd, R. K. J. Am. Soc. Mass Spectrom. 1998, 9, 643-648) which proposed that the concept of fitness for purpose addresses the needs of a wide range of analytical problems. There is a need to define fitness for purpose within the current context of mass spectrometry and to recommend processes for developing and evaluating methods according to suitability for a particular purpose. The key element in our proposal is for the interested parties to define in advance the acceptable degree of measurement uncertainty and the desired degree of identification confidence. These choices can serve as guideposts during method development and targets for retrospective evaluation of methods. A series of more detailed recommendations are derived from basic principles and also from reviews of current practice. This report highlights some areas where consensus is evident, but also revealed the need for further work in other areas. The recommendations are aimed primarily for the laboratory analyst but we hope they will be accessible to the non-scientist as well. Our goal was to provide a framework that can support informed decisions and foster discussion of the issues, because ultimately it is the responsibility of the analyst to make choices, provide supporting data, and interpret results according to scientific principles and qualified judgment.