Centrifuge tubes are containers that hold substances to be analyzed. They are designed to fit centrifuges, a type of laboratory equipment that spins samples at high speeds to separate components within them. Many laboratory processes rely on centrifuges, and centrifuge tubes are engineered to fit perfectly, maintain the centrifuge's balance, and stay in place during rotation. The following is an introduction to the specifications, sizes, materials, and usage methods of centrifuge tubes. ### Specifications and Sizes of Centrifuge Tubes The specifications and sizes of centrifuge tubes mainly include length, diameter, thickness, etc. Here is a detailed breakdown: - **Diameter**: Common diameters of centrifuge tubes are 0.5mm, 1.5mm, and 2mm. Among them, 1.5mm and 2mm tubes are more frequently used. The 1.5mm tube is narrower, suitable for separating small samples, while the 2mm tube is longer, ideal for larger samples and longer centrifugation processes. - **Length**: Typical lengths include 35mm, 50mm, 115mm, and 120mm. The 35mm and 50mm tubes are shorter and generally used in handheld mini-centrifuges, while the 115mm and 120mm tubes are longer, suitable for regular centrifuges. - **Thickness**: Common thicknesses are 0.5mm, 0.6mm, and 0.8mm. In addition, centrifuge tubes come in various volume specifications, such as 0.5mL, 1.5mL, 2mL, 5mL, 10mL, 15mL, and 50mL. Different specifications are suitable for centrifugation experiments with samples of different volumes. When selecting a centrifuge tube, it is necessary to determine the appropriate specification based on experimental needs and equipment compatibility. ### Materials of Centrifuge Tubes Centrifuge tubes are generally classified by material into **plastic** and **glass** types. Plastic centrifuge tubes are more commonly used and can be further divided into PP, PC, PS, etc. Manufacturers choose different plastic materials based on specific requirements: - **PC (Polycarbonate)**: Has good air permeability and high hardness, and can be autoclaved. However, it is not resistant to strong acids, strong alkalis, or some organic solvents such as alcohol. It is mainly used for ultra-high-speed centrifugation above 50,000 rpm. - **PE (Polyethylene)**: Opaque, inert to acetone, acetic acid, hydrochloric acid, etc., but softens at high temperatures. - **PP (Polypropylene)**: Semi-transparent, with good chemical and temperature stability, but becomes brittle at low temperatures, so centrifugation should not be performed below 4°C. - **PA (Polyamide)**: A polymer of PP and PE, semi-transparent, with very stable chemical properties but poor heat resistance. - **PF (Polyfluoride)**: Semi-transparent, usable at low temperatures, suitable for experimental environments between -100°C and 140°C. - **CAB (Cellulose Acetate Butyrate)**: Transparent, suitable for dilute acids, alkalis, salts, as well as alcohol and sucrose gradient determination. - **PS (Polystyrene)**: Transparent, hard, stable in most aqueous solutions, but corroded by many organic substances. It is mostly used for low-speed centrifugation and is generally disposable. ### Usage Methods of Centrifuge Tubes 1. **Select the appropriate centrifuge tube**: Choose a centrifuge tube of the right size and type according to experimental needs, ensuring it meets the specifications of the centrifuge. When filling liquids, select a tube based on the material's resistance to the reagent; not all reagents are compatible with plastic tubes (e.g., strong acids and alkalis may corrode them). 2. **Load the sample**: Place the sample to be centrifuged into the tube, ensure uniform distribution, and close the lid tightly. 3. **Install in the centrifuge**: Place the sample-filled tube on the centrifuge rotor, ensuring balance. 4. **Set centrifugation parameters**: Adjust the centrifuge's speed and time according to experimental requirements. 5. **Perform centrifugation**: Start the centrifuge and allow the sample to separate under the set parameters. 6. **Sample collection or storage**: After centrifugation, remove the supernatant or store the sample in the tube as needed. ### Usage Notes 1. Since graduated centrifuge tubes are "to-contain" measuring instruments, they must be cleaned and dried before use. 2. Centrifuge bottles are used for processing large-volume samples and have raised graduation marks on the side. When reading, ensure correct observation of the meniscus to avoid errors. 3. The number of centrifuge tubes used depends on the centrifuge model. For example, when using a centrifuge with double sleeves for a single-tube experiment, the other sleeve must be filled with an equal volume of liquid to maintain balance. 4. Centrifuge tubes must be compatible with the centrifuge. Select tubes of appropriate length and thickness based on the centrifuge's configuration. Tubes must be balanced during centrifugation: due to high-speed rotation, unbalanced weight distribution can cause sharp noises at best, or even damage the rotor, leading to it flying out and injuring operators in severe cases. 5. After centrifugation, when the tube is in the centrifuge sleeve for separation, allow the rotor to stop naturally after rotation; never force it to stop manually. ### At What Speed Do Glass Centrifuge Tubes Break? If the centrifugation time is set to 5 minutes and not manually stopped, the speed will start to increase from the set value after 5 minutes. Glass centrifuge tubes have a maximum tolerance of 3,000 rpm; exceeding this speed makes them prone to breaking. Therefore, plastic tubes must be used for higher speeds. The above is an introduction to "specifications, sizes, materials, usage methods of centrifuge tubes, and the speed at which glass centrifuge tubes break." A friendly reminder: different centrifuge tubes have varying abrasion resistance, so it is advisable to conduct pre-experiments to determine if a tube can withstand the intensity and duration of oscillation. Sources: Anjunyan Instruments, Cida Biotechnology