Laboratory centrifuges are crucial separation equipment in fields such as biology, chemistry, and medicine. They achieve rapid separation of different components in samples through the centrifugal force field generated by high-speed rotation. This article will systematically explain the technical logic and usage methods of centrifuges from three aspects: core principles, operating standards, and maintenance points.

　　1、 The core principle of centrifugal separation: the game between centrifugal force and settling coefficient

1. Construction of centrifugal force field

When the centrifuge rotor in the laboratory rotates at high speed, the particles in the sample are subjected to an outward centrifugal force (Fc=m Ω² r), which is proportional to the particle mass (m), angular velocity square (Ω²), and rotation radius (r). For example, at a speed of 10000rpm, the centrifugal force at a radius of 10cm can reach more than 5000 times the gravity of the Earth, which is sufficient to rapidly settle micrometer sized organelles.

2. Differentiation of settlement velocity

According to Stokes' law, the settling velocity (v) of particles is directly proportional to the square of particle size (d ²) and density difference (ρ p - ρ m), and inversely proportional to the viscosity of the medium (η). The laboratory achieves the separation of different components by adjusting the rotational speed (controlling ω) and rotor type (changing r):

① Differential centrifugation: low-speed separation of cell debris (e.g. 3000rpm, 10min), high-speed precipitation of organelles (e.g. 15000rpm, 20min);

② Density gradient centrifugation: Spread a gradient of sucrose or iodixanol in the sample, and use density differences to achieve precise separation of virus particles and cell fragments.

3. Adaptability of rotor design

① Angular rotor: The centrifugal force direction is perpendicular to the rotor axis, suitable for high-density samples (such as bacterial precipitation);

② Horizontal rotor: centrifugal force parallel to the rotor axis, reducing sample resuspension, commonly used for low-density separation such as DNA extraction;

③ Zone rotor: Through the design of an annular cavity, continuous flow separation of large capacity samples is achieved, increasing efficiency by more than three times.

　　2、 Standardized operating procedures: dual guarantee of safety and efficiency

1. Sample pretreatment

① Balance and balance: symmetrically place the centrifuge tube with an error of ≤ 0.1g to prevent rotor vibration from damaging the bearings;

② Capacity control: The filling amount should not exceed 2/3 of the volume of the centrifuge tube to avoid liquid overflow and corrosion of the rotor during high-speed rotation.

2. Parameter settings

① Speed selection: Refer to the instruction manual based on the sample type (e.g. 3000rpm is commonly used for blood separation, 20000rpm is required for cell lysis);

② Speed curve: Set slow acceleration/deceleration (such as reaching the target speed within 5 minutes) to prevent sample delamination and damage.

3. Operation monitoring

① Observe noise: If there is abnormal vibration or sharp sound, stop the machine immediately for inspection;

② Temperature control: Setting the freeze centrifuge to 4 ℃ can inhibit enzyme activity and prevent DNA degradation.

Conclusion: The precise separation of laboratory centrifuges relies on the three-dimensional synergy of "principle understanding parameter optimization standardized operation". Researchers need to select suitable rotors and centrifugation conditions based on sample characteristics, and establish equipment maintenance records (such as operating hours and maintenance records) to achieve a dual improvement in separation efficiency and equipment lifespan. In the context of increasingly strict biosafety requirements, the sealing design and explosion-proof certification (such as UL certification) of centrifuges have also become important considerations when choosing.