Molar mass

Molar mass, exact mass and elemental composition for any formula, compound or SMILES, with the isotope pattern, HRMS adducts and an elemental analysis check.

Formula or compound

Read as a formula
Examples:

Hydrates with · or *, charges as Fe3+ or SO4{2-}, labelled atoms as [13C] or D.

Molar mass

C16H20F6N5O6P

Molecular formula

Molar mass523.329g/mol
Monoisotopic mass523.1055Da
Nominal mass523Da
Rings plus double bonds
7
Details
Monoisotopic mass
523.105539 Da
Average mass, unrounded
523.329181 g/molShown above to 3 decimals, the precision of the least precise standard atomic weight in the formula.
Mass defect
0.1055 Da
Atoms
54

Isotope pattern

M · C16H20F6N5O6P · most intense peak 523.1055

0255075100523.0523.5524.0524.5525.0525.5526.0526.5527.0527.5523.1055100%524.108319.6%525.11063.05%%mass (Da)
IonFormulam/z
C16H20F6N5O6P 523.1055
C16H21F6N5O6P+ 524.1128
C16H20F6N5NaO6P+ 546.0948
C16H20F6KN5O6P+ 562.0687
C16H24F6N6O6P+ 541.1394
C16H22F6N5O6P2+ 262.5600
C16H20F6N5O6P+ 523.1050
C16H19F6N5O6P− 522.0983
C16H20ClF6N5O6P− 558.0749
Peak list
Mass (Da)Relative intensityAbundance
523.10554100.00 %81.2814 %
524.1083519.59 %15.9233 %
525.110583.05 %2.4831 %
526.112980.348 %0.2829 %
527.115270.033 %0.0270 %

Elemental composition

ElementAtomsMass (g/mol)Mass %
C Carbon16192.17636.72
H Hydrogen2020.1603.85
F Fluorine6113.99021.78
N Nitrogen570.03513.38
O Oxygen695.99418.34
P Phosphorus130.9745.92

Elemental analysis

ElementCalcd (%)Found (%)Δ
C36.72——
H3.85——
N13.38——
Anal. Calcd for C16H20F6N5O6P: C, 36.72; H, 3.85; N, 13.38.
How the masses are calculated

The molar mass sums the IUPAC standard atomic weights, using the conventional value for elements whose weight is given as an interval (hydrogen 1.008, carbon 12.011, sulfur 32.06). It is shown to the number of decimals of the least precise atomic weight in the formula, so CuSO4·5H2O gets two decimals because of sulfur; the unrounded value is under Details.

The monoisotopic mass uses the mass of the most abundant isotope of every element, the nominal mass its mass number. Labelled atoms, written [13C], D or T, count with their own nuclide mass and are taken as fully enriched. For an ion, one electron mass, 0.000 548 579 909 u, is subtracted per positive charge and added per negative charge.

How the isotope pattern is computed

Every element's natural isotope distribution is raised to its atom count by repeated squaring, and the element distributions are then convolved with each other. In centroid mode the isotopologues are grouped by nominal mass and each group is reported at its intensity-weighted mean m/z, which is what a mass spectrometer at ordinary resolution shows; this is exact apart from dropping contributions below 10−12 of the largest. Fine structure keeps isotopologues apart, merges those closer than 0.1 mDa and drops those below 10−8 of the largest, which resolves, for example, 34S from 13C2.

Adduct m/z values follow m/z = (M + adduct − z·me) / |z|. The copy button gives the line in the form the ACS journals print, for example “[M + H]+ Calcd for C8H11N4O2 195.0877”. The ACS guidelines ask that found and calculated m/z agree within 0.003 m/z units, the limit the found m/z check uses.

Elemental analysis

Calculated percentages are mass fractions from the standard atomic weights. Journals ask for found values within ±0.4 % (absolute) of the calculated ones. If a sample holds solvent, enter it as a solvate, for example 0.5 × H2O, and the calculated values are for C8H10N4O2·0.5H2O.

Sources

Standard atomic weights: IUPAC Commission on Isotopic Abundances and Atomic Weights, “Standard atomic weights of the elements 2021”, Pure Appl. Chem. 94, 573 (2022). Isotope masses and natural abundances: NIST, Atomic Weights and Isotopic Compositions for All Elements (Standard Reference Database 144). Electron mass: CODATA 2018, Rev. Mod. Phys. 93, 025010 (2021). Reporting criteria: ACS Author Guidelines for The Journal of Organic Chemistry and Organic Letters.