[SynDude]

As an organic chemists we have quite some tools to tell us something about the quality of the materials we bought or made ourselves. Fast tools like 1H-NMR and HPLC-MS are the ones our company mainly uses.

However, inorganic compounds like CuBr cannot be analyzed with either technique and its quality drops over time when subjected to air. When a chemist is taking an (old) bottle from our store he/she wants to make sure the chemical is still of high quality. Of course, one can look at things like color or even melting points. But it would be much nicer to have a (spectral) technique that can identify your technique by running it against a library and tell you what you have and what its quality is.

Does anybody know of such a technique that can also be handled by novice users it order to get a quick analysis of the material in the container?

Thanks!

[Arkcon]

This is a complicated question, made all the worse by your scope -- you have a novice performing your organic synthesis?

OK, so, you have SOP's I have to assume, governing NMR and IR spec of your organic raw materials, and you've written acceptance characteristics.  Now you need something for the inorganic reagents.

For Cu(I), you've got an easy answer you've already mentioned, reduced Cu(I) is white or brown (I can't remember) and oxidized, or spent or degraded Cu(II) is blue.  There's a reason why we use any inorganic reagent, but you'll have to come up with a simple reaction that tells you its fitness.  Something colurmetric for each reagent that you can quickly read in the UV-Vis spec (assuming you have one.) 

You can start by listing them all, and what reaction they're meant to perform.

Meantime, you can just say, "Must be freshly prepared"  Then, save some, and evaluate portions over time, to establish storage times.

[SynDude]

Not really novice; PhD and 15 years of hands on custom organic synthesis.

The problem really is, and perhaps I should have made it more clear, that I work at a company that mainly focuses on custom organic chemistry. That basically means that we have >10,000 chemicals in stock which we use for all our syntheses so we cannot make SOP's for each and every single one of them. Organic compounds are checked by 1H-NMR against the spectra that our vendors supply and/or HPLC-MS (and common sense  )

The CuBr was just an example (it needs to be green and turns into white over time when not properly stored), we have (much) more inorganic compounds in store and I'd say most of them cannot be checked visually. Checking all of them over time simply takes too much time and still doesn't guarantee that the material is mistreated by a fellow chemist (e.g. forgetting to close the lid properly, or worse..)

The 'must be freshly prepared' option is no good either. If a compound is out of spec, we do not bother purifying them, we just buy a fresh bottle as this is often cheaper and usually faster too. The thing is, we have a capital worth of compounds in stock that we do not want to throw out. It is also nice to be able to start a synthesis immediately and not having to wait a day (or more) for the chemicals to arrive.

UV-Vis is indeed an technique that can help if a sufficiently large library of spectra is available (and some software to interpret the spectra).
Does anyone have some experience with NIR?