The sedimentation of the Blood bank centrifuge is directly linked to the centrifugal force, and the centrifugal force is linked to the centrifugal method and the rotation speed!
The sequential application of the sedimentation field flow fractionation of the Blood bank centrifuge can greatly extend the separation range of the molecular weight in one experiment. There are two ways to achieve sequentialization: gradually changing the speed of the Blood bank centrifuge or changing the density of the carrier. The concentration of sucrose is often increased in water. Start with a strong field to separate the sample with the smallest molecular weight, then gradually reduce the rotation speed or stop the rotation completely to promote the large molecular weight sample to leaching out of the column. Using this sequence, the different sizes of polystyrene particles are successfully separated. Latex, which is equivalent to a 1000-fold difference in molecular weight.
The rate zone centrifugation method is to load a density gradient medium (such as sucrose, glycerol, KBr, CsCl, etc.) into the Blood bank centrifuge tube before centrifugation. The sample to be separated is placed on the top of the gradient solution, at the bottom of the Blood bank centrifuge tube or in the middle of the gradient layer. The gradient was Blood bank centrifuged together. After centrifugation, the density of the medium at the near-rotation axis (X1) is the smallest, and the density of the medium (X2) farthest from the axis of rotation is the largest, but the maximum medium density must be smaller than the minimum density of particles in the sample, that is, ρP>ρm. This method is based on the difference in sedimentation velocity of the separated particles in the gradient liquid, and the particles having different sedimentation velocities are divided into a series of zones in different density gradient layers to achieve separation from each other. The gradient liquid acts as a supporting medium and a stabilizer during the centrifugation and after centrifugation to avoid re-mixing of the layered particles due to mechanical vibration.
Since ρP>ρm knows that S>0, the centrifugation time of the centrifugation method is strictly controlled, and there is sufficient time for each particle to form a zone in the medium gradient, and to control before any particle reaches the precipitation. If the centrifugation time is too long, all the samples can reach the bottom of the Blood bank centrifuge tube; the centrifugation time is insufficient and the sample has not been separated. Since this method is an incomplete settlement, the settlement is greatly affected by the size of the substance itself, and is generally applied to the case where the material size is different and the density is the same. Commonly used gradients are Ficoll, Percoll and sucrose.
Conversion of Blood bank centrifuge speed and centrifugal force: (calculation formula for Blood bank centrifuge separation factor)
1. The meaning of the separation factor:
The ratio of the partition coefficients of the two solutes under the same conditions in the same extraction system. The larger (or smaller) the separation factor, the better the separation of the two solute, the separation factor is equal to 1, the two solutes are inseparable. The separation factor on the Blood bank centrifuge refers to the relative centrifugal force.
2. The main factors affecting the separation factor:
Centrifugal force does not exist as a real force. In the non-inertial system, it is a force that is convenient for calculation. Please see the following instructions: Centripetal force causes an object to be attracted to a central point, or to repulsion or any tendency to point to it. Descartes interprets centrifugal force as a tendency for an object to maintain its "limited amount." The difference is that the centripetal force is under the inertial reference frame, and the centrifugal force is the force in the non-inertial system. When we deal with physics, we are all in the inertial system (Newton's law is established), so the concept of centrifugal force is generally not used. Since it is not a concept at all, we cannot compare their direction and size.