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This has the potential to bring affordable chemical assays into reach of the average consumer. The nootropics community will love this, making it easy to verif

by fouc 8y ago

This has the potential to bring affordable chemical assays into reach of the average consumer. The nootropics community will love this, making it easy to verify the composition of the bulk powders ordered from India or China.

CamperBob2 8y ago
It looks like the technique relies on the beam from a transmission electron microscope in the 200 kV range. These voltages, in turn, require very high vacuum compared to (e.g.) a more-common scanning electron microscope that's within reach of smaller labs and serious amateurs. The sample must be maintained at cryogenic temperatures, presumably to make it stay put at the molecular level. Last but not least, they apparently need to rotate the sample stage to keep the sample from being blasted to pieces by the electron beam. So unfortunately, the hardware isn't going to be easily packaged into something that consumers can afford. If I had to come up with a drug-identification device, I would probably look into low-field NMR. You aren't trying to visualize the structure, right, just figure out what elements are present in what proportions?
- jcranmer 8y ago
  If you want to match chemicals against a database, particularly organic ones, the easiest thing to build would be an IR spectrometer. You get a lot of random peaks in the sub-2000 cm¯¹ that is pretty damn unique, even for fairly close analogues. It's not going to be useful to determine a compound if it's not in the database, but that's usually not what you want in a identification device for consumer use. > You aren't trying to visualize the structure, right, just figure out what elements are present in what proportions? Elemental analysis is both rather easy (just burn it and measure out the CO₂/H₂O/NO₂/SO₂ + other impurities) and rather useless (a cyclohexane and a hexene both have the same chemical formula yet have very different structures and very different reactive potentials). Inside chemical labs, NMR is the go-to method for identifying "is the compound in this jar what the label says it is?" But that's largely because every chemical lab has an NMR machine already, NMR makes all the functional groups pop out without much work, and if it's not in your database, you can still do a reasonable start on identification with just ¹H NMR. Considering the expense of NMR versus IR spectroscopy, database matching applications probably suffice with IR.
garmaine 8y ago
That’s not what this technique does. And for that, a commodity mass spec would work just fine right now.
sigstoat 8y ago
go find some friendly drug chemists with GC/MSes. they can do what you want, cheaper, tomorrow.

by fouc 8y ago

CamperBob2 8y ago

It looks like the technique relies on the beam from a transmission electron microscope in the 200 kV range. These voltages, in turn, require very high vacuum compared to (e.g.) a more-common scanning electron microscope that's within reach of smaller labs and serious amateurs. The sample must be maintained at cryogenic temperatures, presumably to make it stay put at the molecular level. Last but not least, they apparently need to rotate the sample stage to keep the sample from being blasted to pieces by the electron beam. So unfortunately, the hardware isn't going to be easily packaged into something that consumers can afford. If I had to come up with a drug-identification device, I would probably look into low-field NMR. You aren't trying to visualize the structure, right, just figure out what elements are present in what proportions?

jcranmer 8y ago
If you want to match chemicals against a database, particularly organic ones, the easiest thing to build would be an IR spectrometer. You get a lot of random peaks in the sub-2000 cm¯¹ that is pretty damn unique, even for fairly close analogues. It's not going to be useful to determine a compound if it's not in the database, but that's usually not what you want in a identification device for consumer use. > You aren't trying to visualize the structure, right, just figure out what elements are present in what proportions? Elemental analysis is both rather easy (just burn it and measure out the CO₂/H₂O/NO₂/SO₂ + other impurities) and rather useless (a cyclohexane and a hexene both have the same chemical formula yet have very different structures and very different reactive potentials). Inside chemical labs, NMR is the go-to method for identifying "is the compound in this jar what the label says it is?" But that's largely because every chemical lab has an NMR machine already, NMR makes all the functional groups pop out without much work, and if it's not in your database, you can still do a reasonable start on identification with just ¹H NMR. Considering the expense of NMR versus IR spectroscopy, database matching applications probably suffice with IR.

garmaine 8y ago

That’s not what this technique does. And for that, a commodity mass spec would work just fine right now.

sigstoat 8y ago

go find some friendly drug chemists with GC/MSes. they can do what you want, cheaper, tomorrow.