A rapid-mixing design for conventional NMR probes

Area of Science:

• Analytical Chemistry
• Physical Chemistry
• Spectroscopy

Background:

• Rapid mixing is crucial for time-resolved studies in various chemical and biological applications.
• Traditional stopped-flow techniques can involve complex mechanisms with switches or relays.
• Integrating rapid mixing directly within Nuclear Magnetic Resonance (NMR) probes presents unique challenges.

Purpose of the Study:

• To present a simple, switch-free stopped-flow design for rapid mixing within an NMR probe.
• To utilize magnetic torque for actuating the start and stop valves of the mixing device.
• To characterize the mixing and stabilization times achieved by the novel stopped-flow system.

Main Methods:

• A stopped-flow device was designed, incorporating a current-leading coil.
• Magnetic torque from the coil was used to operate the start and stop valves.
• Two serially arranged tangential jet mixer blocks were employed for homogeneous mixing.
• The performance was evaluated by mixing various liquid combinations and analyzing their 1H NMR spectra.

Main Results:

• The device successfully achieved rapid mixing of liquids within the NMR probe without switches or relays.
• Filling times were measured in the 50-100 ms range.
• Subsequent stabilization times were observed in the 10-40 ms range.
• Factors influencing the mixing process were analyzed and discussed.

Conclusions:

• A simple and effective stopped-flow design actuated by magnetic torque has been developed for NMR applications.
• The system provides rapid and homogeneous mixing with short filling and stabilization times.
• This design offers a promising alternative for time-resolved NMR experiments requiring fast sample manipulation.