Sample prepping gets better all the time – cleaner, faster, and cheaper. One of the reasons for better speed and cleaner sampling is the arrival of disposable polypropylene pipette tips, that you throw away after a single use. These really lower processing time, and they do away with any fear of cross-contamination.
One of the old bottlenecks in laboratory processing is solid-phase extraction. It’s entirely possible to use disposable tips for this too.
The general idea in disposable-tip extraction is that you’ve got a tip with sorbent in it, either powdered or dispersed between two disks, or ‘frits’, as they’re called, which allow bidirectional fluid flow but prevent contamination of the syringe. You can get reversed-phase sorbents, for non-polar to medium polar compounds, you can get strong cation exchanger sorbents, and weak anion exchanger sorbents, and so on.
One of our popular products here at Next Day is the Cryo-Safe™ freeze controller from Bel Art. It’s a well-engineered piece of equipment. It absolutely assures a drop in cell temperature of 1°C per minute, and a lot of labs want that, at high precision.
But where does that 1°C gradient rule come from? And is it right for every possible application?
It’s a fair question, and not every person in every lab is always clear about this. So here’s an answer, first in the form of a review of the general challenges in cryopreservation, and then a bit of discussion about cooling rates, and how they’re derived.