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]. 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 (Download 2020 XLS for corrections) | ||||||
| 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+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)
All information from Fiehn Lab.