Winston-Salem State University 1 article published in JoVE Chemistry A Study of the Complexation of Mercury(II) with Dicysteinyl Tetrapeptides by Electrospray Ionization Mass Spectrometry Johanna Mazlo1, Maria Ngu-Schwemlein2 1Department of Chemistry and Biochemistry, University of North Carolina at Greensboro, 2Department of Chemistry, Winston-Salem State University The characterization of complexes formed in different relative ratios of mercury(II) to dicysteinyl tetrapeptides by electrospray ionization orbitrap mass spectrometry is presented.