“Using the myoglobin protein-protoporphyrin IX (heme) complex, the following reagents were shown to increase ESI charging: benzyl alcohol , m-nitroacetophenone, m-nitrobenzonitrile, o-NBA, m-NBA, p-NBA, m-nitrophenyl ethanol , sulfolane (tetramethylene sulfone), and m-(trifluoromethyl)-benzyl alcohol.”