Nanophotometer n60

The originally formulated 20 mg/ml h2E2 mAb contains 0.01% PS 80, and is the only available mAb drug substance for this mAb. Since PS 80 surfactant cannot be readily eliminated by dialysis due to its large micellar size and small CMC , we concentrated this material as is to 120 mg/ml using Centriprep 30 centrifugal concentrators, knowing that some of the PS80 would be concentrated along with the mAb. The concentrated mAb was then subsequently sterilized using 0.22 μm Millex-GP filters, yielding a final mAb concentration of 120 mg/ml (measured by the absorbance at 280 nm). All UV A280 nm mAb concentration measurements were performed without dilution using an Implen N60 nanophotometer and an applied sample volume of 1.5 μl. For each reformulation buffer tested, approximately 2.7 ml of 120 mg/ml mAb was dialyzed 3 times vs approximately 330 ml of buffer each time, at 4°C, over a total time period of 22 hrs (3 hrs, 4 hrs, and 15 hrs dialysis at 4°C). 3-4 ml volumes of the reformulated mAb solutions were examined for particulates and turbidity in glass tubes using white light illumination from behind and underneath the sample glass tubes. In addition, 200 μl volumes of each 40°C heat-treated sample were examined for particulates and turbidity in clear, thin-walled PCR tubes, using white light illumination from behind the tubes.