Question

What is meant by M + 1 in regards to MS? Explain your answer using an example.

Answer 1

generally in mass spectra we used to get mass of the compound that used to represnt as a [M]

but some times we used to see [M+1] peak this is regarding isotopic mass

let me take one example which is phenol

here the mass value we will get is

[M] = m/z: 94.0419 (100.0%) along with that you will get small peak which is

[M+1] = 95.0452 (6.5%)

along with oxygen 16 (O¹⁶ ) oxygen 17 (O¹⁷) also we wil be there which is only 6.5% so we will observe small peak with [M+1]

this effect is more in the case of Cl and Br