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Comparing Mass Spectra: When Do They Match?



Stephen E. Stein


A common method of determining the identity of a compound is to compare its spectrum against a known standard spectrum of the same substance. Comparisons can be made based on a variety of criteria. How does an analyst know that a match has occurred when comparing mass spectra? Everyone who analyzes mass spectra already has an answer to this question, however, different analysts may use different criteria for evaluating the same data. This can result in 'operator dependent' answers. This presentation discusses some of the factors that need to be considered in any attempt identify a compound through the comparison of its spectrum to a standard.What level of confidence can an analyst possess in calling the identity of an unknown compound by mass spectrometry (MS)? The simplest answer to this question is to ask if the measured spectrum matches the reference compound based on a set of requirements for determining a match. The stricter the requirements for a mass spectral match, the greater the potential for a false negative result. Setting restrictions on matching spectra requires replicate studies, to measure spectral variability. This can be especially difficult when spectra may depend on the matrix or are near the detection limit of the system where key peaks are not detected or their abundances are highly variable.
International Conference of Racing Analysts and Veterinarians


analyst, mass spectrometry


Stein, S. (2003), Comparing Mass Spectra: When Do They Match?, International Conference of Racing Analysts and Veterinarians (Accessed June 21, 2024)


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Created January 1, 2003, Updated February 17, 2017