Introduction

FlatSpin stirrer is an analog magnetic stirrer used in laboratories for mixing or stirring different solutions to obtain homogenous mixtures. A magnetic stirrer consists of a polypropylene body with a hot plate on the top and a magnetic bar stirrer. The instrument uses a magnet rotating around a fixed vertical axis below a horizontal flat surface. A vessel containing desired fluid is placed on the spinner’s flat surface, and a magnetic stirrer bar is placed in the container. The rotation of the magnet under the horizontal surface keeps the magnetic stirrer bar moving, thereby mixing the solid and liquid components to create a homogenous mixture and facilitating heat and mass exchange in the mixture. A flat spin stirrer is frequently used in biochemistry and pharmacology laboratories for preparing and analyzing samples. 

A flat spin stirrer comprises two chief components, i.e., control electronics and motor. The motor is responsible for the stirring action. Motor movement with a magnet on the top causes the stir bars to rotate, which facilitates the mixing process. Control electronics, on the other hand, monitor motor function. Magnetic stirrers are used to mix the fluids of different viscosities. Stir bars can be rotated at different speeds and can be used to mix volumes up to 1L. Preferably, the experimenters should use glass vessels while working with magnetic stirrers, as glass does not affect their magnetic field. While buying a flat spin stirrer, one must consider the rotation speed, oscillation intensity, and heating.

Principle

Magnetic stirrers work by creating a rotating magnetic field by using a rotating magnet or stationary electromagnet. A flat spin stirrer is an analog magnetic stirrer that uses a vortex and magnetic field to prepare homogenous liquid-liquid or solid-liquid solutions. The control electronics energize the motor, which causes the magnet on the top of the motor to rotate, generating a rotating magnetic field. This rotating magnetic field then derives the magnetic stir bar in the vessel placed on the top of the spinner. Consequently, the circular motion of the stirrer creates a vortex in the liquid container, thus accomplishing the purpose of mixing. 

Apparatus and Equipment

Conduct Science offers FlatSpin Stirrer with an ultra-flat compact design and lightweight body. The device has a polypropylene body with an ABS heating plate on the top. In addition, the plate is chemically resistant and has a 90mm diameter. The magnetic stirrer is fabricated from polytetrafluoroethylene (PTFE). Moreover, the motor’s speed range varies between 15-1500 rpm and its automatic reverse rotation feature enables stable stirring with no spillage. This multi-voltage stirrer, with dimensions of 175 x 120 x 15 mm and 0.3kg weight, can stir liquids of up to 0.8L volume. This FlatSpin Stirrer can fulfill your stirring needs by occupying minimal storage space.

Protocol

Prepare the mixture to be homogenized in a glass vessel. Place the glass vessel on the hot plate on the stirrer’s top. Add the magnetic stirrer bar to the solution and press the power button. Then, adjust the rotation speed using the “+” and “-” buttons. Allow the solution to agitate for desired time. Press the power button to turn off the instrument and remove the vessel. 

Applications

FlatSpin stirrer serves manifold applications in biochemistry, pharmacology, and microbiology laboratories. The researchers can use it for preparing homogenous mixtures during several experiments like organic synthesis, oil analysis, extraction, dialysis, soil suspension, buffer solution preparation, and much more. 

Liquid-Liquid Equilibrium Experiments

FlatSpin stirrer is frequently used in liquid-liquid equilibrium (LLE) experiments. For instance, Wang et al. (2019) used it to study this equilibrium and correlation in ternary systems (a physicochemical system comprising three components). The researchers took 1- butanol, butyl acetate, ethylene glycol, 1,3-propanediol, and ethanolamine. They fixed the mass of butyl-acetate and changed the mass of the other two components by increasing one and decreasing the other correspondingly. Following this, they added the three components into a 25ml round bottom flask and sealed it. The investigators used a FlatSpin stirrer to agitate the reagents. They placed the flask on the top of the stirrer for two hours at 298.15K temperature and then allowed the mixture to settle. Later, the samples were analyzed. By measuring selectivity (S) and distribution constant (D), the scientists concluded ethanolamine to be the best extractive solvent. 

Similarly, Zhang et al. (2017) prepared an LLE system for selecting an effective solvent for separating pyridine from coal tar. For this purpose, the researchers selected three imidazolium-based ILs, including 1-butyl,3-methylimidazolium hydrogen sulfate, 1-butyl,3-methylimidazolium dihydrogen phosphate, and 1-butyl,3-methylimidazoliumpercholate. They prepared ternary mixtures using these three ILs, pyridine and methylbenzene. The volume of ILs was fixed, and that of the other two components was varied in a way that one increased and the other decreased correspondingly. The mixtures were added to an LLE device and vigorously mixed on a FlatSpin Stirrer for 4 hours at 298.15K. The scientists allowed the mixtures to settle for 15 hours and then analyzed them. They concluded from LLE data that all ILs showed strong interactions with pyridine than methylbenzene. 

Strengths and Limitations

FlatSpin stirrer has numerous advantages. Due to its compact design, the apparatus consumes very little space on the benchtop. Therefore, it is best suitable for labs with less working space. It is stable, spill-proof, and easy to operate. The researcher can turn it on using the power button and then adjust the speed using the + and – buttons. A magnetic stirrer reduces the time required to mix solutions mechanically. The worker can perform another laboratory task while the mixture is being homogenized. Magnetic stirrers are quitter than gear-driven stirrers, more efficient, and have no external parts that can break or get damaged. However, these stirrers also have a few disadvantages. For example, they can only be used for small experiments and are unsuitable for mixing thick fluids or solutions with high viscosity.

Precautions

• Keep the instrument clean and dry. Avoid accidents and prevent solutions from entering the equipment’s housing as it can damage the machine. 
• Properly ground the instrument to avoid accidents.
• Properly clean the magnetic bar before and after use to avoid solution contamination. 
• To prevent vibration during operation, use the instrument at medium speed for up to 8 hours or at high speed for up to four hours.

Summary

• FlatSpin stirrer is an analog magnetic stirrer used in laboratories for agitating liquid-liquid and liquid-solid solutions to obtain homogenous mixtures. 
• A magnetic stirrer consists of a polypropylene body with a hot plate on the top and a magnetic bar stirrer. 
• The instrument uses a magnet rotating around a fixed vertical axis below a horizontal flat surface. A motor moves and causes the top magnet to rotate, generating a rotating magnetic field.
• A flat spin stirrer is an analog magnetic stirrer that uses a vortex and magnetic field to prepare mixtures. 
• FlatSpin stirrer serves manifold applications in biochemistry, pharmacology, and microbiology laboratories.

References

Wang, Z., Liu, K., Wang, P., Xu, D., Gao, J., Zhang, L., … & Wang, Y. (2019). Liquid-liquid equilibrium measurements and correlation for ternary systems (butyl acetate+ 1-butanol+ ethylene glycol/1, 3-propanediol/ethanolamine) at 298.15 K. Journal of Chemical & Engineering Data, 64(8), 3244-3249.

Zhang, L., Xu, D., Gao, J., Zhang, M., Xia, Z., Ma, Y., & Zhou, S. (2017). Separation of the mixture pyridine+ methylbenzene via several acidic ionic liquids: Phase equilibrium measurement and correlation. Fluid Phase Equilibria, 440, 103-110.