vortexing

Vortexing is the process of forming a vortex, a swirling flow around a central axis, in liquids. In laboratory practice, vortexing refers to using a vortex mixer to rapidly agitate small volumes in tubes or microplates by imparting circular motion to the liquid, creating a vortex that promotes mixing.

Operation and specifications: A vortex mixer drives an attachment or the tube holder in a rapid circular motion. Users choose a speed, expressed in revolutions per minute (rpm), and a mixing time. Typical applications involve low-viscosity liquids in microcentrifuge tubes, PCR tubes, or 96‑well plates. Higher viscosity, larger volumes, or fragile samples may require alternative mixing approaches. Containers should be compatible with vortexing, and seals should be arranged to prevent leakage and minimize aerosol formation while allowing venting if appropriate.

Physical basis: The rotating motion entrains liquid to form a surface vortex with a central core of reduced pressure. The resulting flow is influenced by viscosity, surface tension, and geometry. At higher speeds, turbulence increases and mixing is more rapid, but excessive speeds can cause foaming, splashing, or sample loss.

Applications and considerations: Vortexing is widely used to mix reagents, resuspend pellets, and homogenize samples in chemistry and biology workflows. It is generally unsuitable for viscous liquids, volatile solvents, or substances requiring gentle handling. Proper technique, appropriate tube selection, and adherence to safety guidelines help ensure effective mixing and minimize contamination or exposure.