Obtaining blood serum

Technique to obtain blood serum
Obtaining blood serum
Published on 19/3/2022 by Jose Cancino ‐ 3 min


To obtain blood serum, a centrifuge with adapters for blood collection tubes (CT) will be used, in which CTs with coagulation activators (red colored) can be placed.

These tubes are coated with silicone inside and contain tiny silica particles that accelerate the coagulation process.

CT with separator gel

Obtaining the sample

The procedure starts with the blood collection and identification of the sample with a unique code that lacks any personal information of the patient. The day and exact time of blood collection will be recorded.

Immediately after extraction, the tube should be gently inverted several times to promote coagulation (4 times maximum), then the tube will be kept in an upright position. The sample must be transported to the lab within 45 minutes.

Sample processing

In the lab, the clot formation will be verified otherwise it is advisable to wait for the clot formation (15-30 minutes after collecting the sample). The sample will be processed within the first two hours after extraction and will be discarded if it is not processed within 24 hours.

The TC will be centrifugued at 1600 G (3,600 RPM for rotors with a radius of 112mm) for 15 minutes. At the end of the centrifugation, a clear and transparent supernatant will be visible, with a slight yellowish coloration corresponding to blood serum.

Separate the supernatant with a Pasteur pipette taking care not to touch the interface gel if yellow CTs are used. Aliquot 0.5 ml of the blood serum in each of the microcentrifuge tubes or in cryovials (4 to 6), which should be properly labeled and identified. (3,4)

Serum preservation

The serum samples will be kept in the refrigerator until use, it is important to verify the correct sealing of the microcentrifuge tubes. If the serum is not used in the next 2 or 3 days, it should be frozen in cryovials at -80ºC for one week.


  1. Distribuciones Científicas NESSLER. Tubo para extracción con gel separador de suero. Madrid: Nessler [Internet]. [cited 19 mar 2022]. Available from: https://www.dcnessler.com/fungibles-pdfs/tubo-bd-gel-separador.pdf
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