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

C34H40Cl2N4O6

Molecular formula

Molar mass671.62g/mol
Monoisotopic mass670.2325Da
Nominal mass670Da
Rings plus double bonds
16
Details
Monoisotopic mass
670.232490 Da
Average mass, unrounded
671.616000 g/molShown above to 2 decimals, the precision of the least precise standard atomic weight in the formula.
Mass defect
0.2325 Da
Atoms
86

Isotope pattern

M · C34H40Cl2N4O6 · most intense peak 670.2325

0255075100670671672673674675676677678670.2325100%672.230672.6%671.235638.9%673.233126.3%674.229915.9%675.23144.89%%mass (Da)
IonFormulam/z
C34H40Cl2N4O6 670.2325
C34H41Cl2N4O6+ 671.2398
C34H40Cl2N4NaO6+ 693.2217
C34H40Cl2KN4O6+ 709.1956
C34H44Cl2N5O6+ 688.2663
C34H42Cl2N4O62+ 336.1235
C34H40Cl2N4O6+ 670.2319
C34H39Cl2N4O6− 669.2252
C34H40Cl3N4O6− 705.2019
Peak list
Mass (Da)Relative intensityAbundance
670.23249100.00 %38.4911 %
671.2356538.92 %14.9820 %
672.2306072.60 %27.9438 %
673.2331526.29 %10.1204 %
674.2298815.92 %6.1289 %
675.231364.89 %1.8824 %
676.233590.997 %0.3837 %
677.236010.154 %0.0594 %
678.238490.019 %0.0075 %

Elemental composition

ElementAtomsMass (g/mol)Mass %
C Carbon34408.37460.80
H Hydrogen4040.3206.00
Cl Chlorine270.90010.56
N Nitrogen456.0288.34
O Oxygen695.99414.29

Elemental analysis

ElementCalcd (%)Found (%)Δ
C60.80——
H6.00——
N8.34——
Anal. Calcd for C34H40Cl2N4O6: C, 60.80; H, 6.00; N, 8.34.
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.