As new technologies develop, they can end up bringing back some old ones. That might be the case for infrared spectroscopy. Most organic chemists use it infrequently – in my case, years go by between taking an IR spectrum. There are infrared sensors that can go right into a reaction mixture (or flow stream), and these can be very useful, but they’re also quite expensive – not something that everyone has sitting around ready to go.
But nano materials can do a lot of odd things with electromagnetic waves, and it turns out that you can make surfaces that respond very robustly to changes in infrared wavelengths through a combination of effects (piezoelectric, nano-scale plasmonic). This opens up the way to doing extremely small-scale analysis in real time, directly from solutions or on crude material without any sample prep. This new paper in Angewandte Chemie demonstrates this down into the picogram range with indomethacin as a test compound (here’s another paper from the same group. To put it mildly, you are not going to get that kind of sensitivity with any classic IR technique, and this would seem to open the door to putting such sensors in all sorts of apparatus. Flow chemistry, LC purifications, tandem analysis with mass spec and other techniques – if these things really are that tiny, you could drop them into all sorts of applications, and there are really are situations where a vibrational spectroscopy fingerprint could tell you things that other techniques can’t.
So bring on the high-tech nanomaterials. I just wonder how readily they foul under real world conditions, and what range of solvents and pHs they’ll stand up to, but the field is still very young.