What is the base peak?

The most intense and tallest peak in a mass spectroscopy spectrum is referred to as the base peak and it is usually given a height of 100. The tallest peak represents the most abundant ion formed in the ion source and it is also very stable. A base peak m/z value is not going to be the same value as a molecular ion peak for the same compound. For example, the base peak is at an m/z of 43 for acetone, however its molecular ion peak is at an m/z of 58(which is also acetone’s molecular weight). It is important not to get the two m/z base peak and molecular values confused, they are different even for the same compound.