Serofuge

clay adams serofuge

Serofuge

A Serofuge is a piece of laboratory equipment that is used in blood banking by spinning the serum from whole blood red cells. Rouleaux detection,  agglutination grading, and direct antibody testing and antibody identification are just some of the test serum is used for in blood banking. Serofuges may use angled heads, which allows the cells to move along the side of the test tube to the bottom thus facilitating easier re-suspension of the cells. Even though serofuges may all look similar, different models can perform differently, even at the same setting. Each serofuge needs to be calibrated individually for each technique that is used. That will ensure that the optimum length of spin will be achieved in order that clear cut agglutination is produced without it causing false negatives or positives.

In general, 10 x 75 test tubes are used for agglutination grading. 12 x 75 test tubes are the only size that should be used for setting up serological titers and red cell washing. In blood banking, centrifuges should normally be run at speeds of between 3400 and 3500 RPM when they are used for red cell washing and for grading. 1000g is the force or RCA that is recommended for agglutination grading with glass culture tubes. Please Note: When determining the proper force to use, please refer to the collection tube and reagent manufacturer’s guidelines. Glass test tubes are usually centrifuged for 20 to 30 seconds in order to achieve proper blood bank agglutination grading. It is the general consensus of opinion that the longer that glass test tubes are spun, the better the results will be. Centrifuges are set to various different speeds for the forming of mono layers (1000 RPM) in solid phase testing and for whole blood separation.

We recommend that for blood banking purposes, only bench top style centrifuges that have fixed head rotors are used. If a swinging head rotor is used, the cell button may be disturbed when the test tubes are removed.  Swinging head rotors are recommended when the centrifuge is being used for the initial separation of plasma and red blood cells. Angled rotors may leave the the blood at angle thus effecting automated testing. Centrifuge heads that are removable are recommended. This will make it a lot easier to look directly down into the test tubes when reagents are added. In general, blood bank centrifuge heads will hold up to a maximum of 12 test tubes. The exception to this is when a cell washer is being used in which case the centrifuge heads can usually hold up to a maximum of 24 test tubes. You will find below a centrifugation calculator which will help you meet the collection tube and reagent manufacturer’s specifications and standard operating practices. Generally collection tubes are spun for 10 minutes and kept at a g force of under 2700g for blood bank use. Improper initial centrification may lead to false positives or negatives in automated equipment.

calculator

When working with plastic glass test tubes or plastic test tubes, recommendations are often made as to how these should be centrifuged.

With the help of this program, you can determine the necessary rotation speed or the relative centrifugal acceleration (RCA) if you know the radius of your centrifuge and one of the other two values.

To calculate the missing value, enter the two known values here and click “Start”.

Radius r of the centrifuge: cm
Rotations n : min-1
Relative Centrifugal Acceleration RCA : g