Fig. 4. (A) ESI-MS/MS of the protonated [I₇+H]⁺ at m/z 838.6 and (B) ESI-MS³ of [I₇+H−H₂O]⁺ at m/z 820.5 formed upon the release of water from the precursor ion which readily eliminates the pyrrolidone pendant groups. (C) Mechanism proposed to account for the charge driven loss of pyrrolidone.