To investigate the effect of donation time on the quality of blood components, we measured the platelet count and pH on platelet concentrates, and the factor V and VIII:C levels and fibrinopeptide A concentration on fresh-frozen plasma by duration of donation time. Platelet concentrates and fresh-frozen plasma were classified into three groups according to donation time: group 1, less than 10 min; group 2, 10-15 min, and group 3, longer than 15 min. Mean platelet counts of platelet concentrate were: group 1, 8.6 +/- 2.5 (in x 10(10], group 2, 8.1 +/- 2.6, and group 3, 6.5 +/- 3.2 (p less than 0.05). The same pH was maintained in all three groups. The fibrinopeptide A concentrations in groups 1 and 2 were 24 +/- 53 and 169 +/- 64 ng/ml, respectively, while in group 3 all were greater than 200 ng/ml, indicating correlation of a higher fibrinopeptide A level with longer donation time. Although a higher fibrinopeptide A level indicated a greater degree of thrombin generation, assays of factors V and VII:C did not show decreased activity in groups 2 and 3.