We make our positive and negative DAT controls using discarded unit segments. Place the Rh negative blood from 4 to 5 segments in a 12 x 75 glass tube labeled DAT negative and blood from the Rh positive units, again 4 to 5 segments is enough, with 2 drops of anti-D in a tube labeled DAT positive. Invert the tube with the anti-D to mix. Centrifuge the tubes and place on the analyzer. Use the Assign to Position Icon to identify the DAT samples, then choose Apply to Sample. We registered our DAT control as dat pos and dat neg, so they are recognized when we assign the position.These DAT control last about two weeks for us and work just great (and probably would last longer). We keep a log of the unit numbers used in the preparation of the samples and the unit expiration dates.