To determine the formula of a compound using mass spectrometry data, one must analyze the m/z (mass-to-charge ratio) values and the relative abundance of the peaks, particularly the base peak. The m/z values indicate the mass of the ions detected, while the base peak represents the most intense signal, serving as a reference for other peaks. By identifying the molecular ion peak, which corresponds to the intact molecule, one can estimate the molecular weight of the compound. From there, elemental composition can be deduced by considering common isotopes and fragmentation patterns. Additional resources, such as online mass spectrometry tutorials, can provide further guidance on interpreting the data effectively.