Which laboratory tool is used to hold microcentrifuge tubes securely?

The microcentrifuge rack is specifically designed to hold microcentrifuge tubes securely during experiments. These racks often have individual compartments tailored to fit the tubes snugly, preventing them from tipping over or spilling, which is crucial when handling small volumes of liquid that are common in molecular biology and other biological applications.

By using a microcentrifuge rack, researchers ensure that their samples remain organized and accessible while minimizing the risk of contamination or loss of precious samples. This tool is particularly important in settings where multiple samples are processed simultaneously, as it allows for efficient and effective handling of these small containers. Other laboratory tools listed, such as a microcentrifuge, magnetic stirrer, or buret clamp, serve different functions and are not designed for securely holding microcentrifuge tubes.