Final answer:
No more than 2 hours should elapse between the time a blood specimen is collected and the time the plasma or serum is separated from the formed elements. This is vital to maintain the sample's integrity for analysis, as the lifespan of the formed elements in the blood is quite brief.
Step-by-step explanation:
No more than 2 hours should pass between the time a specimen is collected and the time serum or plasma is separated from the formed elements in the blood. This timeline is advised to help maintain the integrity of the sample. When blood is collected, it consists of plasma, as well as formed elements such as leukocytes (white blood cells), erythrocytes (red blood cells), and platelets.
The plasma is separated by spinning or centrifuging the blood at high rotations (3000 rpm or higher). This causes the blood cells and platelets to separate due to centrifugal forces and settle at the bottom of a specimen tube. The pale, thin layer that separates these formed elements from the plasma is known as the buffy coat. This leaves the upper liquid layer, the plasma, which contains water and various necessary substances for maintaining the body's pH and osmotic load.
It is vital to separate the plasma or serum from the formed elements within 2 hours of collection because the lifespan of the formed elements is quite brief, typically only a few hours to a few weeks. Therefore, timely separation is crucial for maintaining the sample’s integrity for further analysis.
Learn more about Blood Specimen Collection