Table IV

Conditions Identified in a Collaborative CDER/Eli Lilly Study To Provide an Effective Range of Product Capture Using CEX. In early-on screening studies, buffer pHs below 5.0 or above 5.7, or conductivities above 6.0, did not favor adequate levels of product yield and thus served as outer boundaries for a subsequent resolution III DoE-based study. Viral clearance of PPV was then determined by TCID₅₀ using an arbitrarily-defined centerpoint based on these boundaries (see Values column). Next, a DoE approach was employed to investigate these product yield–favorable parameter ranges to clear PPV (quantitative polymerase chain reaction). As part of optimizing run fractions, two elution pooling criteria were tested, one which consisted of fewer fractions but was slightly more pure (“narrow pool”) and one containing more fractions so as to provide greater yield (“wide pool”) at the cost of purity. This work in its entirety was eventually published (4).