Currently, I am conducting my research and the blood sample collection will be in a clinical setting wherein the laboratory facilities will be far away from the area of blood sample collection.

My concern is about the best protocol I should follow to preserve blood samples for longer periods as the prospective participants' enrollment process may extend for Six or Seven hours before shipping the samples to the laboratory for the storage.

Is there any blood sample collection protocol or a certain type of tubes that have RNA/microRNA stabilizer that can be a suitable choice for circulating-plasma microRNA stability.