Vials and Stirring

What vial types and sizes do you recommend?

We recommend the following:

4 mL vials manufactured from polypropylene or glass with PTFE/silicone septa.

8 mL screw-thread sample vials manufactured from either clear 33 expansion borosilicate clear glass (Type 1, Class A) or 51A amber glass. 

What thermocouple do you recommend?

We recommend using the Omega 5SC-TT-K-30-36.

Does every reaction require stirring? Is the stir bar location typically centered in the vial creating a vortex type of funnel.

Yes, most reactions need to have some sort of stirring however some chemistries (such as ones that utilize enzymes) rely upon shaking as stir bars could mechanically destroy the catalysts.

Is the speed of the stir bar important or is just agitating the chemistry effective?

If the reaction is homogeneous (only one phase) then typically 300-500 rpm stirring suffices.

If however, the reaction is biphasic (solid-liquid or liquid-liquid) then stirring becomes critical because reactivity is dependent upon the interface interactions. For instance, Prof. David MacMillan’s group at Princeton University has several chemistries that use inorganic bases in organic solvents - here very high stir rates are required (ie >700 rpm).

Under what conditions is maximum stirring beneficial? Is it a given that you always want the max stirring speed available?

Maximum stirring is not always beneficial especially if you have small reaction volumes because your reaction could get dispersed across the vial and no longer have contact with the stir bar.

When using an 8ml vial, is there a difference in using a football-shaped stir bar vs. a rectangular stir bar?

We use cross-shaped stir bars as they tend to be more stable at higher RPMs.

How is the stirring of the chemistry affected if the stir bar is not centered in the vial?

If not centered, stirring turns into tumble stirring (end-over-end) which might be sufficient for some cases but likely not for all.

Is there a noticeable difference between a stirring motion that creates a vortex-like funnel versus the “agitation” of the chemistry?

If your reaction is homogeneous this likely won't matter much.

Light and Intensity

What is the lamp power in watts for each of the wavelengths?

The total radiant flux of the different wavelength LEDs we measured on a sample of one of each is:

450nm – 3.4 W @ 100% intensity
420nm – 1.8 W @ 100% intensity
365nm – 1.5 W @ 100% intensity

What is the characterization of lumen output for the Photoreactor m2?

In a recent study, we measured the light density as 19.63 mW/mm2 at the vial location.

Fan Speed

Can I turn off the fan?

We cannot go lower than the minimum fan speed, as this is the slowest the fan will go without completely turning it off. We do not run it completely off as this will cause the LED to run too hot. Running the LED too hot will either result in a hard failure or will degrade its lifetime, depending on the operating conditions. The only safe way to achieve a higher temperature in the vial is to run the unit in a warmer environment, with the upper limit of 40°C, while either setting the speed to 2800 to maximize the rise or utilizing the target temperature set-point, if there is the risk that 2800 would overshoot.

Still have questions?

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