04-15-03 06:07
No 426838
Is there a "best" (most generally useful) instrument for identifying compounds? I mean what's better to have, a chromatograph (GC), a spectrophotometer, a copy of the CRC, Mossbaur effect, NMR, or other (if you had to choose one)?
Of course, some types of compounds are probably better detected with a given device than others. So, if swim wanted to detect LSD or stuff in "ergot" or wanted to know what 'unwanted' stuff was also there, is there a best instrument? Not that all these things are readily available, however, a clever electronics phisicist tinkerer type might be able to provide a 'how to' for making such a device with stuff from the local stores.
not a chemist
(Hive Bee)
04-15-03 08:06
No 426860
on a lot of things, but if I had one choice, I would say GC/MS. Especially the more modern ones with software programs. I would like to have one for personal use
, but the one I use in school for my Instrumental Analysis class, it costs $80,000.
The working man is a sucker
(Hive Addict)
04-15-03 09:37
No 426874
Depends on how certain you want to be, or also the novelty of your substance. If you follow a well-known synthetic route, a simple melting point determination may be sufficient. However, GC (preferably coupled to MS) can come in handy to determine the presence of impurities (and if you use a MS, you might also be able to characterize them).
However, MS on itself is not always the best identification method, certainly if you want to be sure about the position of certain phenylic ring substituents. For instance, or we talking about 1,2-dihydroxybenzene, 1,3-dihydroxybenzene or 1,4-dihydroxybenzene? Comparing the retention time of your synthesis product with the retention time of an authentic sample can help, but is not always accepted as proof. Hence the need of some more specialized techniques, for instance NMR and IR. These techniques can clear up many difficulties that aren't solved by MS.
NMR-apparatus:
GC/MS setup:
But really, if you are following well-known synthesis procedures, melting (boiling) point determination would be OK.
The faster you run, the quicker you die.
(Hive Addict)
04-15-03 11:10
No 426901
Hey GC_MS, perhaps you know more about those "bench-top NMR" I've heard about. The price tag is simply ridiculous, about $2,000. Is this actually real NMR?
Freaky
(Hive Addict)
04-15-03 11:47
No 426907
Hey GC_MS, perhaps you know more about those "bench-top NMR" I've heard about. The price tag is simply ridiculous, about $2,000. Is this actually real NMR?
No idea Ba... When I need a NMR (about once a year), I bring it to a collegue with access to a device visualized in the picture above. It's simply huge, at least compared to what I'm used to work with. If benchtop NMRs exist and are available for $2,000... it won't take long until there is one in my lab then 
But I usually "specialize" in MS. I'm kind of a "virgin" in anything "beyond" MS.
The faster you run, the quicker you die.
(Stranger)
04-16-03 03:27
No 427107
Yup,
This stuff is really expensive and one needs allot of super-duty expertise to interpret the results. I think, however, that the spectrophotometer (as a do it yourself project) has much promise. I could say purchase a ~9000 line count encoder for $27, an encoder interface for $14, a microcontroller for ~$5 (with programmer and interface ~$40), a really nice diffraction grating for ~$30, and all the rest for dirt and sweat. Some source code would put this up real nice. Oh yeah, so what's the point of all this discourse; just thinking this would be a nice home project and might be nice to post a write up. But, is there any use for the likes of a spectrophotometer in the field of phsychotropic chemistry?
(Hive Bee)
04-16-03 19:18
No 427312
Does anyone have any insights regarding the possibility of a non-enrolled student being granted occasianal use of a GC/MS, or the larger spectroscopy instruments, with a small sample solution in hand at a local college, or University???
"When dogma enters the brain, all intellectual activity ceases" R.A.W.
(Chief Bee)
04-17-03 02:20
No 427426
Not unless you know someone who works there.
(Hive Bee)
04-17-03 03:55
No 427450
There is a book available at your library, or where ever.
It is titled, " The Scientific American Book of Projects for the Amateur Scientist."Circa 1964 or there abouts. I read it when I was a teenager...and I'll bee fifty this December (2003). There is a write up of a home built NMR apparatus.
callen & A.L.F.
04-19-03 02:23
(Rated as: insignificant)
(Stranger)
04-27-03 16:30
No 429751
When I wrote the initial post, I hadn't yet got my copy of "Introduction to Modern Liquid Chromatography." As for now, I'm reading and enjoying this book. Anyway, I thought it worthwhile to follow up: section 4.3 p. 137 describes using a spectrophotometer as an effective and useful means of IDing substances as they pass out of the Chromatography column and as a rout to seperation and isolation. I think, based on my newbee ignorance, that if one could create a chromatography column with a spectrophotometer at the end, it could solve some problems associated with getting good building blocks (pecursors).
chemistry is what seperates us from the beasts