A method of purifying a multispecific antibody of interest, wherein the MAI comprises a heterodimer comprising a first heavy chain polypeptide comprising a first heavy chain variable region and a second heavy chain polypeptide comprising a second HC variable region, wherein the first and the second variable regions have different antigen specificities and different isoelectric points, the method comprising: i) obtaining a composition comprising the MAI, a first parental homodimeric antibody species comprising either at least one copy of the first heavy chain polypeptide or at least two copies of the first heavy chain polypeptide, and a second parental homodimeric antibody species comprising either at least one copy of the second heavy chain polypeptide or at least two copies of the second heavy chain polypeptide; and ii) performing ion exchange chromatography whereby the MAI is separated from the first and the second parental homodimeric antibody species using pH gradient elution, wherein the performing step ii) comprises: a. contacting the composition with a chromatographic material forming a composition-chromatographic material complex; and preparing or equilibrating either: a.i) the composition; or a.ii) the composition-chromatographic material complex; in a first sample of an eluant at a desired starting pH prior to performing the elution, and b. performing an elution step wherein the chromatographic material-composition complex is contacted with the first sample of the eluant at the desired starting pH, wherein the eluant comprises at least two buffering agents that each have a different negative log acid dissociation constant (pKa); and c. flowing a volume of a second sample of the eluant that is prepared at a desired ending pH through the chromatographic material-composition complex, wherein the ionic strength of the second sample of the eluant is essentially the same as the ionic strength of the first sample of the eluant; wherein the MAI, the first parental homodimeric antibody species, and the second parental homodimeric antibody species elute from the chromatographic material in a pH-dependent manner in essentially distinguishable elution volumes, allowing for the purification of the MAI. i) obtaining a composition comprising the MAI, a first parental homodimeric antibody species comprising either at least one copy of the first heavy chain polypeptide or at least two copies of the first heavy chain polypeptide, and a second parental homodimeric antibody species comprising either at least one copy of the second heavy chain polypeptide or at least two copies of the second heavy chain polypeptide; and ii) performing ion exchange chromatography whereby the MAI is separated from the first and the second parental homodimeric antibody species using pH gradient elution, wherein the performing step ii) comprises: a. contacting the composition with a chromatographic material forming a composition-chromatographic material complex; and preparing or equilibrating either: a.i) the composition; or a.ii) the composition-chromatographic material complex; in a first sample of an eluant at a desired starting pH prior to performing the elution, and b. performing an elution step wherein the chromatographic material-composition complex is contacted with the first sample of the eluant at the desired starting pH, wherein the eluant comprises at least two buffering agents that each have a different negative log acid dissociation constant (pKa); and c. flowing a volume of a second sample of the eluant that is prepared at a desired ending pH through the chromatographic material-composition complex, wherein the ionic strength of the second sample of the eluant is essentially the same as the ionic strength of the first sample of the eluant; a. contacting the composition with a chromatographic material forming a composition-chromatographic material complex; and preparing or equilibrating either: a.i) the composition; or a.ii) the composition-chromatographic material complex; in a first sample of an eluant at a desired starting pH prior to performing the elution, and a.i) the composition; or a.ii) the composition-chromatographic material complex; in a first sample of an eluant at a desired starting pH prior to performing the elution, and b. performing an elution step wherein the chromatographic material-composition complex is contacted with the first sample of the eluant at the desired starting pH, wherein the eluant comprises at least two buffering agents that each have a different negative log acid dissociation constant (pKa); and c. flowing a volume of a second sample of the eluant that is prepared at a desired ending pH through the chromatographic material-composition complex, wherein the ionic strength of the second sample of the eluant is essentially the same as the ionic strength of the first sample of the eluant;