1. The Scottish National Blood Transfusion Service Headquarters Unit Laboratory, Edinburgh, Scotland, U.K.
2. The MRC/SNBTS Blood Components Assay Group, Edinburgh, Scotland, U.K.
3. The S-E Scotland Blood Transfusion Service, Royal Infirmary, Edinburgh, Scotland, U.K.
4. The Department of Medical Physics and Medical Engineering, Royal Infirmary, Edinburgh, Scotland, U.K.