A chemical processing apparatus includes a fragmentation device that includes a linear set of stacked electrodes and a voltage control module that forms DC potential wells of opposite polarity for mutual confinement of opposite polarity ions. A method of protein analysis includes confining positive peptide ions and negatively charged reagent anions in, respectively, first and second DC potential wells in a fragmentation device, mixing the ions, in the fragmentation device, and analyzing ion fragments formed in the mixture.