The polymer/aggregate fractions of three human serum albumin preparations (HSA) from different manufacturers were isolated by size-exclusion high-performance liquid chromatography (HPLC) and analyzed by different electrophoretic and immunochemical methods. All of these polymer/aggregate fractions contained only 30–50% albumin. The rest seemed to be mainly heat-denatured haptoglobin which did not react with an anti-haptoglobin serum, whereas the albumin part reacted with an anti-albumin serum. It could be shown that these polymers or aggregates are formed by disulfide bonds between albumin and the small amounts of denatured impurity globulins (haptoglobin, transferrin) during the pasteurization step. The higher the amount of these heat labile globulins in the final preparation before the pasteurization step, the higher was the polymer/ aggregate content of the pasteurized albumin preparation.

To produce a tri(n-butyl)phosphate/sodium-cholate-treated intermediate-purity factor VIII (FVIII) concentrate with a specific activity of about 1 IU/mg, we used a simple gel filtration step with Sephadex G25 to remove the solvent/detergent reagents from the final product. By exchanging the Sephadex G25 gel for a new high-resolution gel (Sephacryl S400 HR), we obtained a high-purity FVIII concentrate, by simultaneous elimination of about 98% of the extraneous proteins and removal of the solvent/detergent reagents, without reducing the FVIII:c yield and without altering the production scheme. With different protein analysis techniques we analysed the resulting FVIII concentrate and, comparing it to the formerly produced intermediate-purity FVIII concentrate, demonstrated improved purity.