Bead Beating: A Primer (continued)


Hard Animal Tissues: Bone/Hair/Nail

Hard animal tissues such as bone, hair, fish scale, and nail are best homogenized using a disproportionally large grinding ball to crack the sample. Most hard tissues are ground cryogenically, using liquid nitrogen to make substances extra brittle. Hair is very fine, making it difficult to grind into a fine powder, while nail is more resilient and requires cryogenic temperatures for homogenization. Bone, however, can be homogenized with buffer because it is naturally brittle when compared to hair and nail.

The size and mass of samples will influence which ball size, bead beater and configuration one should use. As homogenization is the result of crushing the sample between a grinding balls and vessel wall, a hard plastic (such as polycarbonate) is needed. Therefore, samples less than 100 mg are best homogenized in a 4 ml polycarbonate vial with one 3/8” stainless steel or tungsten carbide ball. Larger samples should be processed in a 15 ml polycarbonate vial with two 7/16” stainless steel grinding balls. In the event that stainless steel balls do not have enough energy to pulverize the sample, tungsten carbide grinding balls can be substituted.


1. Hard animal tissue requires grinding vials made of polycarbonate. If bead beating at ambient temperatures, do not overfill tubes with buffer. For cryogenic grinding, omit buffer during the processing. Buffers can be added after grinding, or the sample can be left frozen (and archived) until needed.
2. Prepare samples according to the following table:
4 ml Vials 15 ml Vials
Sample Mass 100 mg Up to 1 gm
Buffer Volume 1 ml 6 ml
Grinding Balls 1 x 3/8" 2 x 7/16”
Processing Time 3-5 minutes 5-10 minutes
Bead Beater Speed High High
3. Process the samples as stated in the table. During longer processing runs, sample may warm and melt.
4. Sample homogenization can be monitored visually. For cryogenic grinding, homogenized sample should appear as a fine powder. With bone, a homogeneous solution is an indication of an effective process. Small flakes of bone may often be present in the bottom of the tube.
5. Frozen samples can be stored. Alternatively, samples can be processed immediately after grinding.

Suggested Products

Balls: 3/8’’ Stainless Steel (GBSS 375-1000-02), 7/16’’ Stainless Steel (GBSS 437-1000-03)
Vial Sets: 24 Well PC Vial Set (PCVS 04-240-03), 15 ml Polycarbonate Vial Sets (PCVS 15-050-22)
Homogenization Vessel: See Appendix A
Homogenizers: Cryogenic grinding requires a GenoGrinder® or Mini G™. See Appendix A.
Cryogenic Option: Cryoblocks (4 ml and 15 ml)