Friday, December 18, 2009
Some subtle, subtle surfaces
There's a new report (free access!) out about how something as simple as glass (you know, that inert material that is always the same once it's been cleaned) can cause problems with sample prep. In this case, microscope slides were silanized to allow for adhesion of some biomolecules. This is a simple, standard reaction, but one that many researchers were suddenly having problems with. After looking at every possible alternative, they had to look at the glass itself and found that its composition had recently changed (despite claims from the supplier that it hadn't). The point here isn't to blame the manufacturer, but to highlight that you shouldn't assume that "inert" surfaces aren't reeking havoc on your chemistry.
This is one of those examples that should be required reading for everyone early on in their careers. There are other examples in a similar vein where clean surfaces will start adsorbing anything they can from solution. Others have discussed this, and it's certainly well known (I hope?!) that cleanliness is essential in capillary viscometry (Ostwald-Fenske, Ubbelohde...). If you are working on very low concentrations, the bulk concentration will begin to noticeably drop. Or if you are working with polymers in small spaces, the adsorbed macromolecules will reach out quite far from the surface and entangle others in their vicinity.
It shouldn't be the first option to troubleshoot, but never rule out that the inert, unchanging surfaces in your equipment might not be so kind.