Metal ions enable better separations for the different BAs, but also induce multiple conformations. The IMS arrival time distributions for the BA isomers (GCDCA, GDCA, GUDCA and GHDCA) with the exact mass of 449.3141 are shown in their A) deprotonated, B) sodiated, C) copper complexed, and D) zinc complexed forms. The multiple peaks observed for the copper and zinc complexed forms illustrate the multiple binding locations for each cation on the BAs.