an ion with a net charge of zero, but has both a positive and negative charge on it

an ion with a net charge of zero, but mass spectrometry has

A dipolar ion containing ionic groups of opposite charge.

A zwitterion (from German "Zwitter" — "hybrid," "hermaphrodite") is a chemical compound that is electrically neutral but carries formal positive and negative charges on different atoms.IUPAC. ,http://www.iupac.org/goldbook/Z06752.pdf IUPAC Compendium of Chemical Terminology, Electronic Version. Retrieved November 12, 2006. Zwitterions are polar and usually have a high solubility in water and a poor solubility in most organic solvents.