The separation of Adeno-associated virus (AAV) Empty and Full by charge-based techniques have been development on several serotypes using ion-exchange chromatography. However, the separation is quite serotype dependent and sometimes process dependent on other factors. Another technique is needed to separate hard-to-separate AAV in order to characterize the empty species. Here we will explore the use of ICIEF to separate a previously failed-to-separated AAV drug substance, and present the method development and assessment of empty species. Talk will cover: -Introduction of iCIEF and empty/full separation. -Development of empty and full characterization by iCEIF. -What has the empty/full characterization by iCIEF tell us.