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Table 3 Number of possible molecular formulas at different levels of mass accuracy and the impact of isotopic abundance accuracy. A mass spectrometer capable of 3 ppm but with 2% correct isotopic pattern outperforms even a (non-existing) mass spectrometer with 0.1 ppm mass accuracy! The results are computed for randomly selected targets, so single results vary but the trend remains. LEWIS and SENIOR check was applied. Candidates with unrelated high element counts were already excluded

From: Metabolomic database annotations via query of elemental compositions: Mass accuracy is insufficient even at less than 1 ppm

  without isotope abundance information 2% isotopic abundance accuracy 5% isotopic abundance accuracy
molecular mass [Da] 10 ppm 5 ppm 3 ppm 1 ppm 0.1 ppm 3 ppm 5 ppm
150 2 1 1 1 1 1 1
200 3 2 2 1 1 1 1
300 24 11 7 2 1 1 6
400 78 37 23 7 1 2 13
500 266 115 64 21 2 3 33
600 505 257 155 50 5 4 36
700 1046 538 321 108 10 10 97
800 1964 973 599 200 20 13 111
900 3447 1712 1045 345 32 18 196