Collecting whole blood and plasma/serum - which tube to use, how to collect plasma/serum (Nov/20/2008 )

I going to collect whole blood for genomic DNA and RNA extraction, and at the same time to collect plasma/serum for ELISA works. Which blood tube i should use? Correct me if i am wrong:

Whole blood: Use BD vacutainer pink cap tube (plain tube?)

Serum: Use BD vacutainer yellow cap tube, and allow for clotting (say 30 mins)

Plasma: Same tube as collection for whole blood, but spin down to collect supernatant for plasma collection

If i going to use whole blood for extraction of DNA, i do not need to spin down?

Besides, for the plasma collection, once the whole blood is spun down, they usually form two layers (yellow on top, red on bottom), which one i should collect to keep for storage and assay?

Any recommendation is most welcomed. Thanks

I would advise you to study possibilities and the use of the vacutainersystem.
There is more than just the color of the caps. Lets look to the pink cap tube.
This is a tube that inhibits the coagulation process but there are several types.
The percentage of liquid tripotassium EDTA is:
In 2 ml and 3 ml tubes: 7.5% (0.184M)
In 4 ml or above tubes: 15% (0.369M)
these give a dilution by the liquid in 4 ml 1% and 3 ml 2% but in spray coated tubes there is none.

Then about collecting plasma after spunning down you will see not two but three layers, first the yellow plasma on top and the red cells on the bottom in between there is a very thin white layer of the leucocytes and platelets, be sure that these not are transferred with your plasma because the proteincontent of these cells will often intefere witn your elisa tests.

The use of serum or plasma in a elisa is dependent on the protein, one test needs serum, another plasma and often both are possible.

If it's for a long term study the collection and storage of the samples is extremly important for the quality of the results thus pay a lot of attention to it.




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I also would like add my request to this thread, as it is similiar.

I would like to collect plasma with a strong preference not to lyse blood cells (erythrocytes) and not to induce clotting. What kind of tubes should I use ?

- Lithium-Heparin
- Potassium-EDTA
- Serum-Gel

Thanks,

Werner

Serum-gel will never deliver plasma

To choose between Lithium-Heparin or Potassium-EDTA depends on witch plasma the test you will use is validated for.
Lysis of the blood cells is mostly caused by centrifuging with a too high G-force (RPM), too be sure let the cells settle by putting the tube upright in a refrigerator for a couple of hours..

Thanks. One more to know: Can we just put BD blood tube in the -80C freezer after blood collection?

We never put BD tubes in the freezer, because all the cells will destroy and it causes lysis and makes it unusable.

We use cryotubes (PP) for freezing, some other types can crack in the freezer.
We never freeze full blood.

In fact, im thinking to store serum/plasma in microcentrifuge tubes in -80c for long term storage. While store whole blood (before extract DNA/RNA) in -80c inside a cryovial tube. The reason why i not going to store serum/plasma in cryovial tube because im budget constraint which not allow me to buy more cryovial tubes. Even the cryovial tubes that i hv now is given free from vendor! and it's not enuf anyway!

tell me if this does and doesn't make sense. thanks