Blood typing is used to determine an individual's blood group, to establish whether a person is blood group A, B, AB, or O and whether he or she is Rh positive or Rh negative. Specimen Requirements: Minimum Volume 1mL. Total Volume 4mL. Whole Blood. Lavender-top (EDTA) tube. Storage Instructions: Specimens should be tested as soon as possible. Samples that cannot be tested immediately should be stored at 2°C to 8°C. Do not freeze red cells.