The preparation of platelet concentrates in additive solutions attracts growing attention since there is the possibility to inactivate pathogens that contaminate cellular blood components. Such inactivation procedures presuppose the reduction of the plasma portion in platelet concentrates. Additionally, the portion of plasma that may be used otherwise is higher if “dry platelets” are produced. Clinically, the reduction of the plasma portion in platelet components may reduce the frequency of adverse reactions, e.g. of allergic reactions. The resuspension of platelets in additive solutions requires the production of “dry platelets” – concentrates containing more than 3000 x 10e+3 per µl. For this purpose, we performed several series of platelet preparations using the TRIMA separator by GambroBCT. Platelet concentrates in the additive solutions PAS II, PAS III and PAS III M were compared with each other and with platelets in plasma by analyses of the in vitro quality of fresh and stored platelet concentrates.