Determine Number of Carbon Atoms Using M+1 Peak
- The [M+1] peak is caused by the presence of the carbon-13 (13C) isotope in the molecule
- Carbon-13 makes up approximately 1.1% of all carbon atoms
- Therefore, the [M+1] peak is much smaller than the M peak as the isotope is less common
- The ratio of 13C to 12C is approximately 1:99
- Thus, the greater the number of carbon atoms present in a molecule the greater the height of the [M+1] peak
- The number of carbon atoms, n, in a compound can be deduced using the [M+1] peak and the following formula: