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Mass Spectrometry Adduct Calculator

Edited by  Tobias Kind May 2010

This calculator allows to identify some adduct ions from ESI-MS (electrospray) mass spectrometry measurements or other soft ionization techniques like CI-MS or FI-MS or FD-MS or APCI-MS or MALDI-TOF.  Actually this task should be done by every good LC-MS software automatically, directly integrated, no questions asked.  You may check out IntelliXtract or esi - a R package for annotation of LC/ESI-MS Mass Signals using xcms. The successful detection of adduct ions requires either pure mass spectra or a deconvolution and peak detection or peak picking step prior adduct assignment.


This template is based on an table from: Huang N.; Siegel M.M.1; Kruppa G.H.; Laukien F.H.; J Am Soc Mass Spectrom 1999, 10, 1166–1173; Automation of a Fourier transform ion cyclotron resonance mass spectrometer for acquisition, analysis, and e-mailing of high-resolution exact-mass electrospray ionization mass spectral data [DOI]. Another important source also including contaminations (solvents, plasticisers, repeating units, solvent clusters) is hidden in the supplement section of  Interferences and contaminants encountered in modern mass spectrometry (Bernd O. Keller, Jie Sui, Alex B. Young and Randy M. Whittal, ANALYTICA CHIMICA ACTA, 627 (1): 71-81) [DOI]

Download the EXCEL table here as [XLS] or [ZIP]. Please check the values carefully, some of the table ion names were lost during translation, for high mass accuracy the mass of the electron must be included (thanks to Jason and Matt) [DOI].

If you are interested in molecular formula determination or determination of elemental compositions and subsequent isomer structure annotation you may find the Seven Golden Rules helpful. After removal of adducts you can enter your results into the Seven Golden Rules software and find highly probable elemental compositions. These elemental compositions can be matched against molecular compound databases to get a first hint of a possible isomer structure. The Seven Golden Rules can be used for low resolution and high resolution mass spectral data.

For quick calculation of formula masses use the Molecular Weight Calculator.
http://www.alchemistmatt.com/mwtwin.html
http://ncrr.pnl.gov/software/

Example:
1) Find Adduct: Taxol, C47H51NO14, M=853.33089
Enter 853.33089 in green box read M+22.9, m/z=876.320108

2) Reverse: take 12 Tesla-FT-MS result out of MS m/z=876.330
suspect M+Na adduct, read M=853.340782, enter this value into formula finder with 2 ppm mass accuracy (CHNSOP enabled) get some thousand results, compare isotopic pattern, get happy.


Table 1. Monoisotopic exact masses of molecular ion adducts often observed in ESI mass spectra 
          Your M here: Your M+X or M-X
          853.33089 876.32
Ion name Ion mass Charge  Mult Mass Result: Reverse:
1. Positive ion mode             
M+3H  M/3 + 1.007276  3+ 0.33 1.007276 285.450906 291.099391
M+2H+Na  M/3 + 8.334590  3+ 0.33 8.334590 292.778220 283.772077
M+H+2Na  M/3 + 15.7661904  3+ 0.33 15.766190 300.209820 276.340476
M+3Na  M/3 + 22.989218  3+ 0.33 22.989218 307.432848 269.117449
M+2H  M/2 + 1.007276  2+ 0.50 1.007276 427.672721 437.152724
M+H+NH4  M/2 + 9.520550  2+ 0.50 9.520550 436.185995 428.639450
M+H+Na  M/2 + 11.998247  2+ 0.50 11.998247 438.663692 426.161753
M+H+K  M/2 + 19.985217  2+ 0.50 19.985217 446.650662 418.174783
M+ACN+2H M/2 + 21.520550  2+ 0.50 21.520550 448.185995 416.639450
M+2Na  M/2 + 22.989218  2+ 0.50 22.989218 449.654663 415.170782
M+2ACN+2H M/2 + 42.033823  2+ 0.50 42.033823 468.699268 396.126177
M+3ACN+2H M/2 + 62.547097  2+ 0.50 62.547097 489.212542 375.612903
M+H  M + 1.007276  1+ 1.00 1.007276 854.338166 875.312724
M+NH4  M + 18.033823  1+ 1.00 18.033823 871.364713 858.286177
M+Na  M + 22.989218  1+ 1.00 22.989218 876.320108 853.330782
M+CH3OH+H  M + 33.033489  1+ 1.00 33.033489 886.364379 843.286511
M+K  M + 38.963158  1+ 1.00 38.963158 892.294048 837.356842
M+ACN+H  M + 42.033823  1+ 1.00 42.033823 895.364713 834.286177
M+2Na-H  M + 44.971160  1+ 1.00 44.971160 898.302050 831.348840
M+IsoProp+H M + 61.06534 1+ 1.00 61.065340 914.396230 815.254660
M+ACN+Na  M + 64.015765  1+ 1.00 64.015765 917.346655 812.304235
M+2K-H  M + 76.919040  1+ 1.00 76.919040 930.249930 799.400960
M+DMSO+H  M + 79.02122  1+ 1.00 79.021220 932.352110 797.298780
M+2ACN+H  M + 83.060370  1+ 1.00 83.060370 936.391260 793.259630
M+IsoProp+Na+H M + 84.05511 1+ 1.00 84.055110 937.386000 792.264890
2M+H  2M + 1.007276  1+ 2.00 1.007276 1707.669056 1751.632724
2M+NH4  2M + 18.033823  1+ 2.00 18.033823 1724.695603 1734.606177
2M+Na  2M + 22.989218  1+ 2.00 22.989218 1729.650998 1729.650782
2M+3H2O+2H 2M + 28.02312  1+ 2.00 28.023120 1734.684900 1724.616880
2M+K  2M + 38.963158  1+ 2.00 38.963158 1745.624938 1713.676842
2M+ACN+H  2M + 42.033823  1+ 2.00 42.033823 1748.695603 1710.606177
2M+ACN+Na  2M + 64.015765  1+ 2.00 64.015765 1770.677545 1688.624235
             
             
             
2. Negative ion mode           
M-3H  M/3 - 1.007276  3- 0.33 -1.007276 283.436354 293.113943
M-2H  M/2 - 1.007276  2- 0.50 -1.007276 425.658169 439.167276
M-H2O-H M- 19.01839 1- 1.00 -19.01839 834.312500 895.338390
M-H  M - 1.007276  1- 1.00 -1.007276 852.323614 877.327276
M+Na-2H  M + 20.974666  1- 1.00 20.974666 874.305556 855.345334
M+Cl  M + 34.969402  1- 1.00 34.969402 888.300292 841.350598
M+K-2H  M + 36.948606  1- 1.00 36.948606 890.279496 839.371394
M+FA-H  M + 44.998201  1- 1.00 44.998201 898.329091 831.321799
M+Hac-H  M + 59.013851  1- 1.00 59.013851 912.344741 817.306149
M+Br  M + 78.918885  1- 1.00 78.918885 932.249775 797.401115
M+TFA-H  M + 112.985586  1- 1.00 112.985586 966.316476 763.334414
2M-H  2M - 1.007276  1- 2.00 -1.007276 1705.654504 1753.647276
2M+FA-H  2M + 44.998201  1- 2.00 44.998201 1751.659981 1707.641799
2M+Hac-H  2M + 59.013851  1- 2.00 59.013851 1765.675631 1693.626149
3M-H  3M - 1.007276  1- 3.00 1.007276 2560.999946 2627.952724



Corrected values (C. Amsler et al., "Review of Particle Physics" Physics Letters B667, 1 (2008))
m(1H)         = 1.00727646677 u = mass of proton; charge +1
m(1H+e-)    = 1.00782504 u = mass of proton + mass of electron
m(e-)         = 0.00054858026 u = mass of electron; charge -1
m(e-)         = 0.00054857990924 u = new determination of electrons mass

The ultimate source of accurate masses and isotope values are IUPAC and CAWIA (Commission on Atomic Weights and Isotopic Abundances) for a list of the latest corrected values please see Pure Appl. Chem., Vol. 75, No. 6, pp. 683–800, 2003

the recommended values A(r) should be included into accurate mass calculators including corrections for positive and negative  charges depending on ionization type (odd or even electron).

[PDF] - ATOMIC WEIGHTS OF THE ELEMENTS: REVIEW 2000 (IUPAC Technical Report)