Practice question

Electrospray mass spectrometry detects multiply charged ions where measured m/z equals neutral mass plus charge-carrying protons divided by number of charges. Mathematically, m/z = (M + z*1.0073)/z. For a peptide weighing 1500 Da with three added protons, total mass becomes approximately 1503 Da, divided by three charges yields about 501 m/z. This charge reduction principle enables detection of large peptides within limited analyzer range. Understanding this calculation is essential for manual deconvolution and interpreting charge-state envelopes observed in protein ESI spectra during proteomic experiments.