Researchers often take the risk of formulating their favorite buffer, or even an unfamiliar buffer, without considering the depth of knowledge required, rather than just following the assembly recipe to ensure that the compounds are added in the correct proportions. Does putting the component in the solution require heat, or does it dissipate heat? What size, shape and empty volume in the flask are appropriate? What is the viscosity of the solution, and does it increase the viscosity when it is mixed or cooled? The answers to these and other questions can determine whether it is better to mix from above or from below.
The magnetic stirrer mixes by connecting a stir bar to a magnetic drive to produce a vortex whose radius and centripetal force depend on the speed of rotation, the length of the stir bar and the viscosity of the solution. If these characteristics are incompatible with each other, the stirring will stop, usually the stirring rod is separated from the magnetic drive and rotates around the flask.
The heating plate magnetic stirrer can be seen everywhere on the commonly used countertops. They can be operated intuitively using daily laboratory supplies without the need to equip too many Erlenmeyer flasks, flat-bottomed beakers and stirring rods. In addition, the all-in-one solution is both simple and convenient, because the heating plate is integrated into the stirring plate without the need for external flames, fixture brackets, and esoteric tools for maintenance and adaptation.
The ubiquitous magnetic stirrer reflects the simplicity of its available functions and options. IKA Corporation offers a variety of hot plate stirrers from the basic model RH series to the high-end RCT series, in which countless digital displays, different maximum temperatures, volumes (always water rated) and rotation ranges can be selected. The highest-priced magnetic stirrer is usually close to the lowest-priced overhead unit. Using any of these magnetic devices, people can safely and simply mix most buffers, thereby extending the life of the instrument.
However, the inert PTFE coating of the stir bar may cause pitting and abrasion over time, thereby attracting and absorbing trace metals, including gold, palladium, nickel, and iron. For analytical chemists who perform reactions driven by metal ion catalysis, this can be an important question, which can accidentally be pushed to the right of a carefully prepared equation. Therefore, it is advantageous to use a stainless steel impeller driven by a motor to stir the solution. In addition, the various impellers, torques and speeds available in the top agitator assembly can improve the accuracy and reproducibility inherent in mixing, homogenizing or emulsifying a range of solutions.
The impeller gives a flowing terrain that is essentially suitable for its environment. The propeller-shaped impeller blades generate motion parallel to their rotation axis, thereby generating a top-down low-shear motion, which is very suitable for stratification or solid suspension. Cross-shaped, pivoting or collapsible blades produce a vertical radial flow that moves the liquid from the side and then vertically, as in high shear emulsification, which requires a higher RPM than a magnetic stirrer. The square produces tangential flow, with low shear horizontal movement, and is most suitable for high viscosity liquids. In fact, the top agitator is dominant in its ability to handle viscosity, especially when the solution formed under heating will increase the viscosity when cooled, such as polymers and emulsions. The ability to place the impeller high or low, centered, or on the edge of its container in all cases, allows for finer control of mixing dynamics and desired results.
Caframo Lab Solutions offers Ultra Torque, Universal and Ultra Speed overhead stirrers, as well as nearly dozens of stainless steel or PTFE impellers and various supports, chucks and chucks. Low-speed Ultra Torque BDC1850 is optimized for high-viscosity mixing, with a maximum torque of 568 Newton cm, while Ultra Speed BDC6015 has the same name as its maximum speed, which is very suitable for emulsification and homogenization. The GM BDC3030 is in the middle ground in terms of speed, torque and capacity, so it is a high road of adaptability.
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