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

C17H19FN4O2S

Molecular formula

Molar mass362.42g/mol
Monoisotopic mass362.1213Da
Nominal mass362Da
Rings plus double bonds
10
Details
Monoisotopic mass
362.121275 Da
Average mass, unrounded
362.423403 g/molShown above to 2 decimals, the precision of the least precise standard atomic weight in the formula.
Mass defect
0.1213 Da
Atoms
44

Isotope pattern

M · C17H19FN4O2S · most intense peak 362.1213

0255075100362.0362.5363.0363.5364.0364.5365.0365.5366.0366.5367.0367.5362.1213100%363.124120.9%364.12056.97%365.12181.12%%mass (Da)
IonFormulam/z
C17H19FN4O2S 362.1213
C17H20FN4O2S+ 363.1286
C17H19FN4NaO2S+ 385.1105
C17H19FKN4O2S+ 401.0844
C17H23FN5O2S+ 380.1551
C17H21FN4O2S2+ 182.0679
C17H19FN4O2S+ 362.1207
C17H18FN4O2S− 361.1140
C17H19ClFN4O2S− 397.0907
Peak list
Mass (Da)Relative intensityAbundance
362.12128100.00 %77.4207 %
363.1240720.93 %16.2059 %
364.120496.97 %5.3968 %
365.121771.12 %0.8661 %
366.123130.130 %0.1006 %
367.124700.012 %0.0092 %

Elemental composition

ElementAtomsMass (g/mol)Mass %
C Carbon17204.18756.34
H Hydrogen1919.1525.28
F Fluorine118.9985.24
N Nitrogen456.02815.46
O Oxygen231.9988.83
S Sulfur132.0608.85

Elemental analysis

ElementCalcd (%)Found (%)Δ
C56.34——
H5.28——
N15.46——
S8.85——
Anal. Calcd for C17H19FN4O2S: C, 56.34; H, 5.28; N, 15.46; S, 8.85.
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.